# Mixing bowls: research notes

Date: 2026-10-25. Scope: bowls sold for mixing and food prep in a home kitchen, singly (open stock) or as nesting sets, in any material (stainless steel, glass, plastic or melamine, ceramic or stoneware, copper, silicone, bamboo), including small prep or pinch bowls sold in mixing-bowl sets. Not stand-mixer replacement bowls (they belong with the mixer), serving and salad bowls sold as tableware, salon colour bowls or pet bowls, which share the words "mixing bowl" on retail search pages.

Bundles stay in this scope (corrected after the blind check, 2026-10-25): bowl sets bundled with a colander or strainer, sets whose lids are grater or slicer discs (10 of 67 Amazon titles), lidded mixing-bowl sets, and "25PCS" sets that pad the count with measuring cups and spoons are mixing-bowl sets first. No sibling takes them: `graters` covers hand tools only, `strainers` covers colanders, sieves and spinners sold alone, `measuring-cups` sends bowls back here, and `containers` / `storage-containers` do not exist yet. `bowls_in_set` and `real_bowl_count` count only their bowls. Lidded bowls sold purely as food storage remain out of scope.

Quote labels: **verbatim** = the sentence in quotation marks was in raw text I read myself (curl plus HTML stripping, pdftotext on a downloaded PDF, or the eCFR API); **fetched excerpt** = the fetch tool summarised or reworded the page; **search excerpt** = the claim came from a search-engine summary. This run had no search excerpts: the session's WebSearch budget was exhausted before research began, so every page was found by URL (site sitemaps, the Internet Archive availability API, sibling notes as leads) and read raw. Nothing below is search-excerpt-only.

## Seed

Seed output, recorded verbatim:

```
=== Example entry (from an unrelated category) ===
category: bedsheets
what this shows: the expert split is often not the number everyone advertises. Thread count is the generic trap here. Weave is what changes how the sheet feels and sleeps.

<example>
{
  "id": "weave",
  "label": "Weave",
  "definition": "The pattern the threads are crossed in, which decides how the sheet feels and how it handles heat.",
  "why_experts_care": "Percale is a simple one-over-one weave that feels crisp and cool and gets softer with washing. Sateen puts more thread on the surface so it feels silky and warmer and shows wear sooner. Thread count, the number most listings lead with, matters far less than which of these two you pick, and above about 400 it is mostly marketing.",
  "kind": "categorical",
  "values": ["percale", "sateen", "linen", "flannel", "jersey"],
  "roles": ["split", "filter"],
  "novice_answerable": true,
  "cold_start_question": "Do you sleep hot, or do you like a sheet that feels smooth and a bit warm?",
  "source": "listing",
  "listing_field_hint": "Usually in the title or the first bullet. Sometimes only in the fabric care tab.",
  "backfill_cost": "low",
  "backfill_note": "When missing, the product photo and the description words 'crisp' or 'silky' usually settle it.",
  "visual": { "chartable": false },
  "priority": { "narrows_set": 4, "cost_to_answer": 1 },
  "evidence": ["wirecutter_sheets", "textile_primer"]
}
</example>

=== Persona ===
A barista trainer, who thinks in the variable most beginners get wrong

Ask yourself two things and write the answers under 'Seed' in notes.md:
  1. What is the mixing-bowls equivalent of the example above?
  2. What would this persona notice first about mixing-bowls that a typical buyer would not?
Keep what survives the data check. Drop the rest.
```

1. **The mixing-bowl equivalent of thread count is the piece count.** It is the number titles lead with ("26pcs", "12 Piece", "8PCS") and it is inflated the same way: lids, grater discs, measuring spoons and pinch bowls all count as pieces. The data check held up: Pyrex's own spec table lists its 8-piece set as four bowls and four lids (verbatim); Wirecutter says the same of the Smart Essentials set (verbatim: "The eight pieces included in the Pyrex set: four bowls and four lids."); on an Amazon search page read 2026-10-25, a "26pcs" set lists six bowl sizes (7, 4, 2.5, 2.0, 1.5, 1 QT), an "8PCS" set is "5PCS Nesting Bowls, 3 Grater Attachments", a "25PCS" set has five bowls plus measuring cups and spoons. The equivalent of weave, the thing that actually changes the experience, is material plus wall shape. **Kept**: `bowls_in_set` facet, `real_bowl_count` metric, the piece-count judgement and trade-off.
2. **The barista trainer's "variable beginners get wrong" is wall shape against the tool.** Buyers pick by size and looks; the testers keep coming back to whether the walls are tall enough for a hand mixer or wide enough to fold. Wirecutter measured it (genoise "⅛ inch shorter" in the deep Cuisinart than in the wide Thunder Group bowl, verbatim). **Kept** as split 3, `bowl_profile`. The trainer would also think about temperature, which suggested bowl-to-saucepan fit for a double boiler (Wirecutter tested "how well each 4- to 5-quart bowl fit in a standard 2-quart saucepan"; Epicurious found Pyrex "a little loose on top of the saucepan"). **Dropped** as a facet: two sources mention it, but no listing gives rim and pan diameters and there is no rule to compute fit. Also **dropped**: Epicurious's line that "Stainless steel stays cool regardless of the temperature in your kitchen, ensuring your dough or batter remains at a cool temperature"; one source, no measurement, and thin steel has little thermal mass.

## Sources and what each supports

### Specialist reviewers who test

**Wirecutter, The Best Mixing Bowls, by Lesley Stockton, updated December 22, 2025** (live page 403; read from the Internet Archive snapshot of 22 July 2026, curl plus HTML stripping)
http://web.archive.org/web/20260722054955/https://www.nytimes.com/wirecutter/reviews/best-mixing-bowls/
- verbatim: "Both materials are heatproof and perfectly safe to place over a pot of simmering water to create a double boiler." "They're also nonreactive, meaning acidic foods like tomatoes, vinegar, and lemon juice won't end up with a metallic taste."
- verbatim: "Glass bowls are much heavier and come in smaller size options than stainless steel ones. The largest bowl we found in a glass set measured 4 quarts (larger sizes, like this 6-quart tempered-glass bowl , are available open stock)"; "Most glass bowl sets max out at 4 quarts."
- verbatim: "If you use a hand mixer, stainless steel bowls are the best option. Glass bowls are weakened on a microscopic level with every drop, tap, and spoon scrape."; "the spinning beaters can scratch or damage the glass, making it more vulnerable to sudden breakage."
- verbatim: "Plastic bowls can't function as a double boiler, while bendable silicone lacks sturdiness and can harbor off smells that may transfer to food. Ceramic bowls are pretty but also very heavy and prone to chipping along the rim."
- verbatim: "We also excluded stainless steel bowls with rubber-coated bottoms because, judging from our experience, the seam between the nonskid coating and the bowl can harbor bacteria and mold."; "If you have kids who like to help around the kitchen, a rubber bottom bowl might be the best option."; Jürgen David: "Just stick it in a cake ring or a small pot to hold it in place."
- verbatim: "Wide, shallow mixing bowls are great for folding and tossing, but they often can't contain splashes from a hand mixer. Although deep and narrow bowls help contain ingredients when you're using a hand mixer or vigorously whisking vinaigrette or cream, they don't allow for the wide range of motion needed to quickly fold whipped batters, and the extra mixing can deflate your end result."
- verbatim: "we think a set of three with capacities of 3, 5, and 8 quarts is perfect for most home cooks. A 3-quart bowl is appropriate for small jobs like whisking dressings, a 5-quart bowl is the right size for whipping up cakes and cookies with a hand mixer, and a big 8-quart bowl is ideal for making potato salad, coleslaw, and stuffing."; "A 4-quart bowl is plenty big for most home dinner prep and simple baking projects that don't involve a hand mixer."
- verbatim: "Glass and thicker-gauge stainless steel bowls are more stable because they're heavier"; "Lower weight is especially important for larger capacity bowls; 10 quarts of food is unwieldy on its own without the extra ounces a thick-gauged metal bowl will add."
- verbatim: "The 4-quart bowl from this Pyrex set weighs almost 4½ pounds, over 3 pounds more than the 8-quart size from Thunder Group".
- verbatim: "The Thunder Group bowls are “standard weight,” but we found that term to be pretty meaningless from one brand to the next."; "The Finedine and Winco bowls were thin and easily dented."; "Winco's standard-weight mixing bowls are thin and flimsy. We found that the bottom popped in and out with the slightest pressure from a spoon or whisk."; FineDine: "three of the six bowls arrived with dents."
- verbatim: "The eight pieces included in the Pyrex set: four bowls and four lids."; "The Luminarc 10-piece tempered-glass mixing bowl set has a lot of bloat".
- verbatim: "The genoise cake we made in the 5-quart Thunder Group bowl was the loftiest we made in our tests."; Cuisinart genoise "⅛ inch shorter".
- verbatim: Cuisinart set "1½, 3, and 5 quarts"; Thunder Group "nine sizes (¾ quart to 20 quarts)".
- verbatim: "minor surface damage can, on rare occasions, cause tempered glass to spontaneously shatter down the road".
- verbatim: "We prefer rims that jut straight out to the side with a rolled or slightly bent edge"; "brushed stainless steel bowls added traction".
- Supports: material rules, shape trade-off, size bands, weight, gauge, non-slip base trade-off, piece-count bloat, glass and hand mixers. Confidence high.

**America's Test Kitchen, The Best Mixing Bowls of 2026, by Sarah Sandler, published March 6, 2026** (curl)
https://www.americastestkitchen.com/equipment_reviews/1538-mixing-bowls
- verbatim: "We only tested sets that included a large bowl with a capacity of 4 quarts or more".
- verbatim: "We chose not to test plastic bowls because plastic items shouldn't be used in the microwave or with hot foods as that can cause them to release microplastics into food. They can also retain oils and stains"; "We also skipped ceramic sets because they tend to be available only in limited sizes and they're heavy and expensive."
- verbatim: "Even a large 8-quart bowl often weighs less than a pound."; "The main downside to stainless-steel bowls is that they can't go in the microwave."
- verbatim: glass "can go in the microwave, which is convenient for melting butter or steaming vegetables"; "Their transparent walls are an added bonus for tasks such as monitoring how much your bread dough is rising."; "we couldn't find any glass bowls larger than 4.5 quarts."
- verbatim: "Most of the bowls we tested came in predetermined sets, typically in the realm of 1.5, 3, and 5 quarts. Our favorite stainless-steel bowls, which are sold separately instead of in a set, come as big as 8, 10, or even 20 quarts. Extra-large bowls always come in handy, even for a small household. They're great for proofing bread dough and marinating meat."
- verbatim: lids "a nice bonus"; "Bowls that lacked any sort of rim were more difficult to lift or hold onto during mixing."
- verbatim: plastic-coated steel set: "their plastic coating also means they can't be placed over a pan of simmering water, as we might do for a makeshift double boiler."; OXO: "Because of their plastic coating, the exterior of the bowls shouldn't get hot, so avoid them for uses such as melting chocolate over a pan of simmering water."
- verbatim: "Mixing bowls typically come in two shapes: deep, tall bowls and shorter, shallower bowls."; deep bowls "made it more difficult to scrape out food neatly ... We had to turn them nearly upside down"; "We had a slight preference for bowls with shorter, more gradually sloped walls."
- verbatim: "acidic ingredients such as tomato or lemon can cause materials like uncoated aluminum, copper, or cast iron to leach into food."; "some cooks choose this material for whipping egg whites because the copper ions bond with the proteins in egg whites and help to create a more stable foam."
- verbatim weights: Vollrath Economy "4.4 oz (1.5 qt), 6.8 oz (3 qt), 8.6 oz (5 qt)"; Pyrex 8-piece "1 lb 4.6 oz (1 qt), 1 lb 12.1 oz (1.5 qt), 2 lb 5.5 oz (2.5 qt), 3 lb 10.4 oz (4 qt)", "Tempered soda lime glass with plastic lids"; OXO steel "11.9 oz (1.5 qt), 1 lb 2.6 oz (3 qt), 1 lb 9.8 oz (5 qt)", "Stainless steel with plastic coating and Santoprene base"; Cuisinart "9.2 oz (1.5 qt), 14.6 oz (3 qt), 1 lb 5.9 oz (5 qt)"; All-Clad "12 oz (1.5 qt), 1 lb 3.4 oz (3 qt), 1 lb 10 oz (5 qt)"; White Rhino "Borosilicate glass with plastic lids", "1 lb 1.4 oz (1.1 qt), 2 lb 4.2 oz (2.7 qt), 3 lb (4.5 qt)".
- Supports: material rules, size bands, weights, rim, shape, reactivity, copper. Confidence high.

**America's Test Kitchen, How to Pick the Best Bowl Shape for the Job** (curl)
https://www.americastestkitchen.com/articles/6319-choose-right-bowl-shape
- verbatim headings and lines: "Tall and Wide ... Good for: Mixing batter by hand; emulsifying vinaigrettes ; tossing salads; whisking cream, egg whites, and dry ingredients"; "Tall and Narrow ... Good for: Proofing dough , beating with a hand mixer, food storage ... Steep sides make it easier to tell when a dough has doubled; they also contain splatters"; "Wide and Shallow ... Good for: Folding, tossing salads ... The wide expanse reduces the number of strokes needed to blend ingredients, resulting in a lighter, airier batter."
- Supports: the shape split; ATK names three shapes, the review two. The register keeps two values (see Trimmed detail). Confidence high.

**America's Test Kitchen, These Mixing Bowls Will Change Your Cooking, 17 Feb 2023** (curl)
https://www.americastestkitchen.com/articles/6924-vollrath-mixing-bowls
- verbatim: "wider rims are easier to grip"; "Rims that curve outward direct the flow of liquids neatly"; "The broad, shallow shape of these inexpensive bowls put food within easy reach and allowed for wide turns of a spatula."
- Supports: rim facet. Confidence medium-high.

**America's Test Kitchen, Mini Prep Bowl Sets** (curl)
https://www.americastestkitchen.com/equipment_reviews/1650-mini-prep-bowl-sets
- verbatim: "despite the manufacturer's claims, the bowls in this set held only about 5 1/3 ounces, not 6 1/2"; "most of the sets we tested contained bowls of only one size (usually between 4 and 8 ounces)"; silicone bowls "tenaciously retained odors"; stainless prep bowls "couldn't be microwaved".
- Supports: stated capacity is approximate (one measurement; kept out of the JSON as a number); prep bowls are a few ounces. Not cited in category.json. Confidence medium.

**Epicurious, The Best Mixing Bowls** (found through the Epicurious sitemap; curl)
https://www.epicurious.com/expert-advice/the-best-mixing-bowls-product-review-article
- verbatim: "Unlike their shallower competitors, the Cuisinart bowls' deep interior and tall sides kept my counter completely free of spray and spatter even when using a hand mixer on high speeds."
- verbatim: "Some sort of non-slip bottom might have helped as they did slide around if not gripped tightly, but on the other hand, something like a silicone bottom would have prevented them from serving as double boilers."; OXO steel: "these had rubber grips on the bases—which was exactly what ultimately took it out of the running for “best metal bowls,” because they couldn't be fashioned into double boilers."
- verbatim: "Stainless-steel bowls are inexpensive, durable, and lightweight ... and they can do double duty as double boilers. But they are not microwave-safe."
- verbatim: "Plastic and melamine bowls are durable and shatterproof but generally less versatile than either stainless or glass because they cannot be used as double boilers and often can't be put in the microwave. They also have a tendency to scratch over time, making them inferior for tasks like whipping egg whites, which can be ruined by any fatty residue trapped in the crevices. Plastic also tends to trap odors and discolor over time when exposed to ingredients like tomato sauce or turmeric."
- verbatim: "You might be seduced by a set with six different bowls, but if more than one of them are smaller bowls so tiny that they are basically glorified ramekins, what's the point? Instead ... look for a range that includes at least one small (1–1½ quart) prep bowl and two larger bowls in the 3- to 8-quart range"; "In general, you can find mixing bowls in the following sizes: 1½, 2, 2½, 4, 5, 6, 8, 10, and 12 quarts."
- verbatim: glass "much heavier than stainless-steel bowls ... On the other hand, you might welcome the weight that allows the bowl to stand firm on the counter".
- verbatim: copper "has ions that bond with an egg while you're whipping it—and those ions stop the eggs from deflating".
- verbatim: FineDine "felt flimsier and more cheaply made".
- Supports: third tester for every material rule, shape, non-slip trade-off, plastic weaknesses, set bloat. Confidence high.

### Brand spec sheets (which fields brands publish)

**Pyrex, 8-piece Mixing Bowl Set with Assorted Lids** (curl)
https://pyrexhome.com/products/pyrex-8-piece-mixing-bowl-set-with-assorted-lids
- verbatim: "Durable high-quality tempered glass"; "Bowls are dishwasher and microwave safe"; "BPA-free plastic lid is top-rack dishwasher and microwave safe".
- verbatim table: "Mixing Bowl 1 7'' diameter x 3'' high 1 quart / Mixing Bowl 1 8.5'' diameter x 3.25'' high 1.5 quarts / Mixing Bowl 1 9.75'' diameter x 3.75'' high 2.5 quarts / Mixing Bowl 1 11.75'' diameter x 4.5'' high 4 quarts", then four lids.
- Fields listed: material, dishwasher and microwave flags, warranty, then a per-item table of diameter, height and capacity, lids as separate pieces.

**Pyrex, 6-piece Stainless Steel Mixing Bowl Set** (curl)
https://pyrexhome.com/products/pyrex%C2%AE-6-pc-stainless-steel-mixing-bowl-set
- verbatim: "Includes (1) 4.2-quart mixing bowl and lid with handle, (1) 2.5-quart mixing bowl with lid, (1) 1.5-quart mixing bowl with lid"; "high quality 304 stainless steel". A second six-piece set that is three bowls. Not cited in JSON (the 8-piece table carries the point).

**Pyrex, Product Warranties, Safety and Usage** (curl)
https://pyrexhome.com/pages/product-warranties-safety-and-usage
- verbatim: "There are three primary risks: 1. Breakage due to sudden temperature change. 2. Breakage due to impact if the item is dropped or knocked against a hard object."; "DO NOT use on or under a flame or other direct heat source, including on a stovetop"; "DO NOT use or repair if broken, chipped, cracked or severely scratched."; "DO NOT strike utensils against glassware or ceramicware."; glassware "Can be used for cooking, baking, warming, and reheating food in microwave ovens".
- verbatim, under "PYREX STAINLESS STEEL MIXING BOWLS": "DO NOT use in microwave, under a broiler or browning elements, or on stovetop."
- verbatim: "Plastic lids are not airtight."
- Supports: glass care rules, steel never microwaved, lids not airtight. Confidence high. Note the tension: Pyrex bans direct heat; Wirecutter calls tempered glass "perfectly safe" over simmering water. Over water is not direct heat, so they do not contradict, but the register leans to steel for double-boiler work and says it is our call.

**Pyrex, Frequently Asked Questions** (curl)
https://pyrexhome.com/pages/frequently-asked-questions
- verbatim: "Soda lime is slightly more resistant to impact breakage than borosilicate, and borosilicate is slightly more resistant to extreme thermal changes than soda lime. They share the same Use & Care instructions and are equally suited for your home cooking needs".

**Vollrath, 5-quart economy stainless steel mixing bowl 47935** (found through vollrath.com sitemap; curl)
https://www.vollrathfoodservice.com/products/smallwares/kitchen-essentials/mixing-bowls/economy-stainless-steel-mixing-bowls/47935
- verbatim: "26-gauge stainless steel construction is durable and long lasting"; "Mirror finish"; "Beaded edge ensures a secure grip"; table: "(H) Height (IN) | 3.97 | (DI) Diameter | 11.535 | (DiU) Usable Diameter (IN) | 10.787 | (DIB) Base Diameter (IN) | 4.75 | (T) Thickness (IN) | 0.016"; "Capacity (L) | 4.7 | Capacity (QT) | 5"; "Weight (LB) | 0.65".
- Fields listed: gauge, finish, rim, height, rim and usable and base diameter, thickness, capacity in L and qt, weight. The fullest spec sheet in the category.

**Vollrath, 5-quart heavy-duty stainless steel mixing bowl 69050** (curl)
https://www.vollrathfoodservice.com/products/smallwares/kitchen-essentials/mixing-bowls/heavy-duty-stainless-steel-mixing-bowls/69050
- verbatim: "Tall sides, proper weighting and a concave bottom prevent tipping and messes"; "Precise dimensions promise accurate capacity"; "(H) Height (IN) | 4.46 | (DI) Diameter | 11.75 | (DiU) Usable Diameter (IN) | 10.75"; "Weight (LB) | 1.21"; no gauge or thickness given.

**Cuisinart, Stainless Steel Mixing Bowls with Lids CTG-00-SMB** (curl)
https://www.cuisinart.com/stainless-steel-mixing-bowls-with-lids-set-of-3/CTG-00-SMB.html
- verbatim: "The 1.5 qt, 3 qt, and 5 qt bowls are all refrigerator- and freezer-safe, and dishwasher safe"; "Weight : 3.9" (set, unit not shown). No dimensions.

**Mason Cash, Original Cane S12 Mixing Bowl 29cm** (curl)
https://www.masoncash.co.uk/2001004-cane-s12-mixing-bowl-29cm/
- verbatim: "Made from earthenware"; "the wide shallow shape allows for kneading within the bowl"; "The Size 12 Cane Mixing bowl measures 29cm x 14cm, with a capacity of 4 litres"; "The bowl is dishwasher safe."; "a high-gloss glaze providing a chip resistant finish".
- Supports: ceramic bowls are sold by a size number with cm and litres; no microwave statement on the page.

### Regulators

**FDA Food Code 2022, Chapter 4 (copy hosted by a county public health district; pdftotext)**
https://www.c-uphd.org/documents/eh/2022-FDA-Food-Code-Chapter-4-Equipment-Utensils-and-Linens.pdf
- verbatim 4-101.13: "Ceramic, china, and crystal UTENSILS ... that are used in contact with FOOD shall be lead-free or contain levels of lead not exceeding the limits of the following UTENSIL categories"; table: "Large Hollowware ... Bowls > 1.1 Liter (1.16 Quart) ... 1"; "Small Hollowware ... Bowls < 1.1 Liter (1.16 Quart) ... 2.0" (MG/L).
- verbatim 4-101.14: "copper and copper alloys such as brass may not be used in contact with a FOOD that has a pH below 6 such as vinegar, fruit JUICE, or wine".
- The Food Code governs food establishments, not retail products; it is used here as the regulator's statement of the hazard. The lead mg/L figures are single-source in this run (CPG 545.450's PDF would be the second, but fda.gov and the Archive both refused the download), so they stay here and out of the JSON. The pH 6 line has a second source (Snopes, below) and is in the JSON. Confidence high.

**21 CFR 109.16, Ornamental and decorative ceramicware (eCFR versioner API, 2026-10-01)**
- verbatim: decorative ware "will be considered to be for food use unless" it bears "“Not for Food Use. May Poison Food,”" (or one of two other messages) on a label and permanently on the base, or "A hole is bored through the potential food-contact surface."

**FDA, Questions and Answers on Lead-Glazed Traditional Pottery** (live page 404 to curl; Internet Archive snapshot of 25 May 2026)
http://web.archive.org/web/20260525172102/https://www.fda.gov/food/environmental-contaminants-food/questions-and-answers-lead-glazed-traditional-pottery
- verbatim: "When the pottery is fired at the proper temperature for the proper amount of time, essentially all the lead is bound into the glaze."; problem types include pottery "purchased from flea markets or street vendors" and "brightly decorated in orange, red, or yellow color"; "Pottery not listed above that was made in commercial factories for everyday use is much less likely to have problems related to lead."; "no amount of washing, boiling, or other process can remove lead from pottery."

**FDA, CPG Sec. 545.450 Pottery (Ceramics); Import and Domestic, Lead Contamination** (landing page via Archive snapshot of 7 Sep 2026; the PDF download was blocked)
- verbatim: "Some ceramic foodwares have been found to leach significant quantities of lead from potential food contact surfaces." Not cited in JSON.

**21 CFR 177.1460, Melamine-formaldehyde resins in molded articles (eCFR API)**
- verbatim: "Melamine-formaldehyde resins may be safely used as the food-contact surface of molded articles"; extractives limit "0.5 milligram per square inch". Background only; not cited in JSON.

### Academic and primers

**McGee, Long and Briggs, "Why whip egg whites in copper bowls?", Nature 308, 667–668 (1984)** (curl; authors from the citation metadata)
https://www.nature.com/articles/308667a0
- verbatim: "Over the past 200 yr, protocols for the production of albumen foams have frequently specified the use of copper reaction vessels"; "We report here that copper utensils reduce the danger of overheating albumen foams, and propose that the mechanism involves the metal-binding protein, conalbumin (ovotransferrin)." The abstract's word is "overheating"; the register paraphrases as "harder to ruin" to stay with the text.

**Wikipedia, Pyrex** (curl)
- verbatim: soda-lime "has around twice the strength — making it more resistant to physical damage when dropped, which is believed to be the most common cause of breakage in glass bakeware. However, its thermal shock resistance is lower"; "Borosilicate's shock resistance is around three times higher than soda–lime."; Consumer Reports "released test results, in January 2011, confirming that borosilicate glass bakeware was less susceptible to thermal shock breakage than tempered soda lime bakeware. They admitted their testing conditions were "contrary to instructions""; "Corning had mostly switched to soda–lime glass for "almost all" of its tableware products" by 1998.
- The two-times and three-times figures are Wikipedia's only (its citations not read), so they are not in the JSON.

**Wikipedia, Borosilicate glass** (curl)
- verbatim: thermal expansion "(3.3 × 10 −6 K −1 ), about one-third that of ordinary soda–lime glass". Background for the glass_type definition; not cited.

**Wikipedia, Tempered glass** (curl)
- verbatim: "when broken, to shatter into small granular chunks instead of splintering into large jagged shards"; "Nickel sulfide defects can cause spontaneous breakage of tempered glass years after its manufacturing."
- Supports: the tempered glass vocabulary entry; corroborates Wirecutter's spontaneous-shatter line.

**Wikipedia, Melamine resin** (curl)
- verbatim: "Melamine resin utensils and bowls are not microwave safe ." Second source for the plastic-and-microwave caution is Epicurious ("often can't be put in the microwave").

**Snopes, Can Drinking Cocktails from a Copper Mug Cause Poisoning?** (curl)
- verbatim: "in keeping with Food and Drug Administration guidelines, copper should not come into contact with acidic foods with a pH below 6. That includes vinegar, fruit juice, wine"; FDA code: "When copper and copper alloy surfaces contact acidic foods, copper may be leached into the food."
- Supports: second source for the pH 6 rule.

### Retail listings (what data is present)

**Amazon.com search, "mixing bowls", read 2026-10-25 with curl** (prices shown in INR because of geolocation; titles unaffected). 67 distinct product titles.
- Any material named: 61 of 67 (steel 34, plastic or melamine 15, glass 7, ceramic or porcelain 2, plus bamboo and wood). The six without: two KitchenAid sets, a Chef Craft "Ss" bowl, a salon bowl, two generic sets.
- Capacity in quarts or ounces: 25 of 67. Piece count: 46. Lids: 33. Non-slip or silicone base: 17. Dishwasher: 9. Microwave: 8. Grater attachments: 10. Gauge or "thickened": 3. Steel grade (18/8, 304): 0. Copper: 0.
- Piece-count examples, verbatim titles: "Thickened Heavy-Duty 26pcs Stainless Steel Bowl ... Sizes 7, 4, 2.5, 2.0, 1.5, 1QT"; "8PCS Stainless Steel Mixing Bowls with Lids - 5PCS Nesting Bowls, 3 Grater Attachments"; "12 Piece Plastic Nesting Bowls Set includes 6 Prep Bowls and 6 Lids"; "WEPSEN Mixing Bowls Set, 25PCS Stainless Steel Mixing Bowl with Lid Set, Large Nesting Bowls 7, 4.5, 3,2, 1.5QT, Measuring Cups and Spoons".
- Off-scope items on the same page: a salon colour bowl set, porcelain cereal bowls, an acacia salad bowl.
- Only titles were read, not product pages. That is why every facet except material is marked `researched`.

### Could not reach

Serious Eats (402 and a People Inc block page, including its sitemap); Food & Wine (same owner, not tried after the block); Wirecutter live (403; Archive snapshot used); fda.gov pages by curl (404) and WebFetch (404 on the melamine and microwave URLs tried); USDA FSIS microwave page (403); FDA CPG 545.450 PDF (blocked on fda.gov and on the Archive, which began rate-limiting this IP mid-run); EUR-Lex Regulation 1935/2004 (empty response); OXO product page (403); Webstaurant (403); Mauviel (no response). The Internet Archive CDX index was offline. WebSearch was unavailable for the whole run (session budget used up by concurrent runs).

## Data points used for derived metrics

Weight per quart, from ATK's weighings (oz per qt):

| Bowl | Capacity | Weight | oz per qt |
|---|---|---|---|
| Vollrath Economy steel | 5 qt | 8.6 oz | 1.7 |
| Vollrath Economy steel | 1.5 qt | 4.4 oz | 2.9 |
| Cuisinart steel | 5 qt | 21.9 oz | 4.4 |
| Cuisinart steel | 1.5 qt | 9.2 oz | 6.1 |
| OXO steel, plastic coating | 5 qt | 25.8 oz | 5.2 |
| All-Clad steel | 5 qt | 26 oz | 5.2 |
| White Rhino borosilicate | 4.5 qt | 48 oz | 10.7 |
| Pyrex tempered soda-lime | 4 qt | 58.4 oz | 14.6 |
| Pyrex tempered soda-lime | 1 qt | 20.6 oz | 20.6 |

Wirecutter: Pyrex Smart Essentials 4 qt "almost 4½ pounds" (about 72 oz, 18 oz per qt), Thunder Group 8 qt "over 3 pounds" lighter (so under about 24 oz, under 3 oz per qt). Vollrath's own spec gives the economy 5 qt as 0.65 lb (10.4 oz, 2.1 oz per qt), heavier than ATK's 8.6 oz; I kept ATK's figure in the JSON and the spread here. The JSON says "at 4 to 5 quarts, steel weighs about 2 to 5 oz per quart and glass 11 to 18": steel 1.7 to 5.2 (ATK) with Wirecutter's under-3 and Vollrath's 2.1 inside it; glass 10.7 to 14.6 (ATK) and 18 (Wirecutter). Small bowls run heavier per quart, which is why the band is stated at 4 to 5 quarts.

Height over rim diameter, from brand spec tables: Pyrex 1 qt 0.43, 1.5 qt 0.38, 2.5 qt 0.38, 4 qt 0.38; Vollrath economy 5 qt 0.34; Vollrath heavy-duty 5 qt 0.38 ("tall sides"); Mason Cash S12 0.48 ("wide shallow shape"). ATK calls the Pyrex bowls "shallow" and the Vollrath heavy-duty is sold on "tall sides" at the same ratio, and Mason Cash calls the deepest-ratio bowl "wide shallow". So the ratio does not separate the two shapes, and the register does not offer it as a derived metric; `bowl_profile` is classified from photos.

Real bowls per set: Pyrex 8-piece = 4 bowls (spec table); Pyrex 6-piece steel = 3 bowls; Amazon "26pcs" = 6 bowls, "21 PCS" = 6 bowl sizes, "25PCS" = 5 bowls, "8PCS" = 5 bowls, "12 Piece" = 6 bowls.

## Against the existing add-on schema

The add-on `zamana-expertise/data/schema-parts/supplies/kitchen/add-ons/mixing_bowl.jsonc` is empty (`{}`). Mixing bowls today inherit kitchen-standard (`materials[]` with roles, `max_heat_temp`, `dishwasher_safe`) and supplies-standard (`high_signal_markdown`, `sizing` with `size_stated`, `pack_count`, `pieces_included_text`, `dimensions`, `capacity`, `weight`, `measurements_text`). Proposals only; nothing in zamana-expertise was edited.

| Facet in this register | In the schema today | Proposed kind under AGENTS.md | Note |
|---|---|---|---|
| material | yes, kitchen-standard `materials[]`, role `body` | vertical anchor (existing) | The enum already has stainless_steel, glass, tempered_glass, borosilicate_glass, plastic, melamine, ceramic, stoneware, earthenware_terracotta, copper, silicone, bamboo. Nothing to add. |
| non_slip_base | yes, expressible as `materials[]` role `base` with silicone or rubber_tpe; a plastic-coated exterior as role `exterior_surface` | vertical anchor (existing) | No new field. The pipeline should fill the `base` role when titles say "non-slip silicone base". |
| glass_type | yes, `materials[]` values tempered_glass and borosilicate_glass | vertical anchor (existing) | Annotation only; do not filter on it. |
| microwave_safe | no | hard filter | Propose add-on `microwave_safe: enum [yes, no, unspecified]`. It is the one heat fact buyers filter on for this leaf, and it is not derivable for plastic or ceramic. Mirrors the `dishwasher_safe` pattern and its "not microwave safe" trap. |
| double_boiler_ok | no | derived at query time | From `materials[]`: body glass → yes; body stainless_steel → yes only when the `base` and `exterior_surface` roles are known and are not silicone, rubber_tpe or plastic, else unknown; plastic → no; copper and ceramic → unknown. Not stored. The base and coating roles need a photo or brand-page read (backfill low). |
| largest_bowl_size | partly: `sizing.capacity` holds one value | sizing (category's bought-by number) | A set has several capacities. Propose add-on `sizing.bowl_capacities: [{value, unit}]` inside `sizing` (it varies by variant), with the largest derived at query time. Alternatively fill `sizing.capacity` with the largest bowl and keep the rest in `pieces_included_text`. |
| bowls_in_set | partly: `sizing.pack_count` (ambiguous: pieces or bowls) and `pieces_included_text` | sizing | Propose add-on `sizing.bowl_count` (number) inside `sizing`, defined as bowls only, so a "26pcs" set reads 6. Lid and gadget counts stay in `pieces_included_text`. |
| lids_included | no | researched (low) | Read from the title when it says "with Lids"; otherwise from `pieces_included_text` or the photo, since a silent title does not mean no lids. Matches category.json (settled 2026-10-25). |
| bowl_profile | no | out of schema (rule 1, photo) | The vision pass classifies it. Dimensions do not settle it (see the ratio table). |
| rim_grip | no | out of schema (rule 1, photo) | Vision pass. "Rolled edge" or "beaded edge" text can go to `high_signal_markdown`. |
| bowl_weight | yes, `sizing.weight` | sizing (existing) | Fine as is. Note brands give set weight (Cuisinart) or per-bowl weight (Vollrath); the per-bowl value is the useful one. |
| steel_gauge | no | high_signal_markdown | "26-gauge", "0.016 in", "heavy-duty" are text facts for the line-by-line pass; too sparse to commit to augmenting as currency. |
| food-contact lead (ceramic) and copper reactivity (judgements) | no | high_signal_markdown | "Lead-free glaze", "unlined copper" are the text signals. Certifications are cut under rule 5. |

Fields this register considers noise for mixing bowls: `max_heat_temp` (nobody shops a mixing bowl by oven temperature; heat use is the microwave and double-boiler questions, which the material answers); `sizing.dimensions.length/width/depth` (a round bowl has one diameter and a height, and neither settles shape; keep diameter only in `measurements_text` for nesting-fit questions); `sizing.size_stated` duplicates capacity for this leaf. `dishwasher_safe` stays: ATK marks down hand-wash-only steel bowls (All-Clad), and the field is already standard.

## Branches

Each leg names the sentence in the register or these notes it follows from. All `when` values are values of the split facet.

**Split 1, material ("Light steel, microwavable glass, plastic, or heavy ceramic?").** The answers are four of the facet's values; copper and "other" are reachable by name (the rationale says copper is "rare in mass-retail listings and asked for by name"; 0 of 67 Amazon titles were copper, while ATK says "Copper mixing bowls are still widely sold"). Skip only on a stated material (corrected 2026-10-25: a microwave answer or a wish to avoid plastic leaves several values open).

- when `glass`: then_ask bowl_weight; makes_irrelevant steel_gauge.
  - bowl_weight: "a 4-quart glass bowl outweighs an 8-quart steel one" (glass trade-off) and the weight-per-quart band in `weight_per_quart`. The weight is the main cost of choosing glass, so it is the next thing to show.
  - glass_type removed from this leg (2026-10-25): the chain glass → microwave → thermal shock → glass type was unstated, and it ran against the register's own judgement that glass type "should not filter" (Pyrex FAQ: "equally suited for your home cooking needs"). The hand-mixer caution for glass is carried by the glass trade-off and the "Glass bowls should not take a hand mixer" judgement, not by a branch, because bowl_profile is asked on every path anyway.
  - steel_gauge irrelevant: the facet is defined as the thickness of "the sheet steel"; a glass bowl has none.
- when `stainless steel`: then_ask steel_gauge, non_slip_base; makes_irrelevant microwave_safe, glass_type.
  - steel_gauge: "Thin steel dents and its bottom can pop in and out under a whisk" (steel_gauge facet) and "the cheapest thin sets dent" (trade-off). Expected fill is near zero (backfill high), so the assistant will often have nothing to show.
  - non_slip_base: "a rubber foot or plastic coating on a steel bowl rules it out" (double_boiler_ok facet) and the non-slip judgement; steel is where the base choice changes what the bowl can do.
  - microwave_safe irrelevant: "Steel is never microwave-safe" (microwave_safe facet; Pyrex use and care, ATK, Epicurious), so the filter is fixed at no on this branch.
  - glass_type irrelevant: defined only for glass bowls.
- when `plastic or melamine`: then_ask microwave_safe; makes_irrelevant double_boiler_ok, glass_type, steel_gauge.
  - microwave_safe: sources split (microwave_safe facet and the plastic-microwave judgement): Epicurious "often can't be put in the microwave", Wikipedia "Melamine resin utensils and bowls are not microwave safe", ATK "plastic items shouldn't be used in the microwave or with hot foods". The register filters on the maker's label and shows ATK's caution.
  - double_boiler_ok irrelevant: "plastic cannot" (double_boiler_ok facet; Wirecutter, Epicurious), so the value is fixed at no.
  - glass_type, steel_gauge irrelevant: defined only for glass and steel.
- No branch for `ceramic or stoneware`, `copper` or `other`: nothing in the register changes the next question for them. The ceramic lead judgement is shown, not asked.

**Split 2, largest_bowl_size ("Biggest job: dressings, a cake or cookies, or bread and crowd salads?").** Values corrected 2026-10-25 to `under 4 qt`, `4 to 5 qt`, `over 5 qt`, which leaves no gap (the old `6 qt and up` left 5 to 6 qt unbinned). Answer-to-value rule, stated in the split rationale: dressings → `under 4 qt`; cake or cookies → `4 to 5 qt`; bread or crowd salads → `over 5 qt`. The band edges are the register's own, built on Wirecutter (3 qt for dressings, 5 qt for cakes and cookies "with a hand mixer", 8 qt for potato salad, coleslaw and stuffing; "A 4-quart bowl is plenty big for ... simple baking projects that don't involve a hand mixer") and ATK (sets "typically in the realm of 1.5, 3, and 5 quarts"; extra-large bowls of 8 to 20 qt "great for proofing bread dough"). "Bread" in the question comes from that ATK line. Skip on a stated size or an earlier answer naming bread or batch cooking; "household size" removed, because ATK says "Extra-large bowls always come in handy, even for a small household."

- when `over 5 qt`: then_ask bowl_weight.
  - bowl_weight: Wirecutter, "Lower weight is especially important for larger capacity bowls" (quoted in the bowl_weight facet as "light weight matters most in large bowls").
  - bowls_in_set removed from this leg (2026-10-25): the chain (top band is mostly open stock → show real bowl count) gave a count of 1 for open-stock bowls, and no cited sentence says bowl count matters more for large bowls.
- No branch for `under 4 qt` or `4 to 5 qt`. An earlier draft had the top band make glass_type irrelevant, since most glass sets stop below 5 qt; dropped, because Wirecutter names a 6-quart open-stock glass bowl.

**Split 3, bowl_profile ("Deep for a hand mixer, or wide for gently mixing by hand?").** Reworded 2026-10-25 so the question no longer depends on the term "folding". The two answers are the facet's two values. Skip only on a stated wall shape: owning a hand mixer leans deep but does not settle it (ATK "had a slight preference" for shallow bowls overall; Wirecutter calls the wide Thunder Group bowl its pick for other mixing jobs), so the rationale treats it as a lean. No branches: shape does not change what else to ask in any sentence of the register.

## Numbers in category.json and how many sources stand behind each

| Number | Sources |
|---|---|
| 3 / 5 / 8 qt for dressings / cakes and cookies / big salads | Wirecutter (verbatim); ATK sets 1.5, 3, 5 and large ≥ 4 qt; Epicurious 1–1½ small plus 3–8 qt |
| ATK tested only sets with a ≥ 4 qt bowl | ATK (verbatim); it is ATK's own method, reported as such |
| Extra-large bowls sold up to 20 qt | ATK (verbatim); Wirecutter Thunder Group ¾ to 20 qt |
| Most glass sets stop below 5 qt | Wirecutter 4 qt; ATK 4.5 qt; the blind checker's Amazon read of 2026-10-25 found glass sets at 4.78 and 4.8 qt (Amazon blocked my re-fetch). Wirecutter names a 6 qt open-stock glass bowl, and the JSON says larger single bowls are sold. |
| Sets stop near 5 qt | ATK 1.5/3/5 typical; Wirecutter Cuisinart 5 qt max; Epicurious Cuisinart 5 qt |
| 5 qt steel 8.6 to 26 oz; 4 qt Pyrex 3 lb 10 oz; Pyrex 4 qt almost 4.5 lb | ATK spec lines (verbatim, listed not stated as weighed); Wirecutter (verbatim). The two disagree by about 13 oz on what appears to be the same Pyrex 4 qt bowl, and Vollrath's own spec (0.65 lb) disagrees with ATK's 8.6 oz; the JSON now says both. |
| Steel about 2 to 5 oz per qt, glass 11 to 15 oz per qt at 4 to 5 qt (Wirecutter's Pyrex near 18, named as an outlier) | ATK listed weights; Wirecutter Pyrex and Thunder Group figures; Vollrath spec |
| 4-qt glass outweighs 8-qt steel | Wirecutter (verbatim); ATK "Even a large 8-quart bowl often weighs less than a pound" against 3 lb 10 oz glass |
| 2-quart saucepan in Wirecutter's test | Wirecutter only; it describes Wirecutter's method, attributed |
| 26-gauge, 0.016 in (Vollrath economy) | Vollrath spec page; brand fact about one product, stated in the hint as an example |
| Pyrex 8-piece = 4 bowls + 4 lids | Pyrex spec table; Wirecutter |
| "26pcs" set with six bowls; 61, 25, 17, 33, 8 of 67 titles | Amazon search page read once (counts are a field-presence sample, not a claim about the market) |
| Height/diameter about 0.38 for Pyrex 4 qt and Vollrath 69050 | Pyrex spec table; Vollrath spec table (each its own product) |
| pH below 6 for copper | Removed from the JSON 2026-10-25: Snopes relays the same FDA code, so the number had one independent source. The JSON now says "acidic food such as vinegar or wine" (Food Code; ATK on acid leaching copper). |
| McGee et al. 1984 | Nature (verbatim abstract); ATK and Epicurious on copper and egg foam |

Kept out of the JSON as single-source: the Food Code lead limits (1 mg/L for bowls over 1.1 L, 2.0 mg/L under), Wikipedia's two-times strength and three-times thermal-shock figures, ATK's 5 1/3 oz versus 6 1/2 oz prep-bowl measurement, the 0.5 mg per square inch melamine extractives limit.

## Dropped

- Steel grade (18/8, 304, 18/0). Pyrex names 304; no tester discusses grade for mixing bowls and 0 of 67 Amazon titles state it. Wirecutter saw rust on Tovolo rims but does not tie it to grade.
- Height-to-diameter ratio as a derived metric (see the ratio table).
- Pour spout and handle as facets. Epicurious liked them on plastic sets (Farberware, OXO), ATK found the All-Clad hooked handle dug into the hand. They are photo-visible extras and do not change which bowl suits a job; rule 1 keeps them out of schema too.
- Insulated (double-walled) steel bowls. One OXO title; no tester coverage.
- Interior measurement markings. One Amazon title; no tester coverage.
- Silicone and bamboo as their own families. Wirecutter rejects silicone ("bendable silicone lacks sturdiness and can harbor off smells"), ATK's prep test found silicone retained odours and Epicurious found Bamboozle bowls not microwave- or dishwasher-safe; together they are a small slice, kept under the "other" value.
- Bowl-to-saucepan fit and "steel keeps dough cool" (see Seed).

## Trimmed detail

- `bowl_profile`: ATK's shape article names three shapes (tall and wide, tall and narrow, wide and shallow); its review and Wirecutter use two. The register uses two values because the question has to offer two clean answers; ATK's "tall and wide" sits with "deep and tall-sided" for the hand-mixer question and with "wide" for folding, which is why it is not a third value.
- `double_boiler_ok`: Wirecutter's test fitted a "4- to 5-quart bowl" in "a standard 2-quart saucepan"; Epicurious found the Cuisinart's rounded bottom "nestled perfectly in one of my saucepans" and the Anchor Hocking 2½-quart "didn't move at all", while Pyrex got "a little loose".
- `material`: ATK's reason for skipping plastic includes "release microplastics into food" when heated; the register does not repeat it, because no second source here makes the claim.
- `non_slip_base`: Wirecutter's own fix is a towel ring, a wok ring or "a cake ring or a small pot" under the bowl.
- `glass_type`: Wikipedia records CPSC's 2008 count of 66 shattering complaints over ten years and its conclusion that Pyrex bakeware "does not present a safety concern"; bakeware, not bowls, so it stays here.
- `largest_bowl_size`: ATK measured one lidded prep-bowl set at "about 5 1/3 ounces, not 6 1/2"; Vollrath sells its heavy-duty line on "Precise dimensions promise accurate capacity".
- Ceramic judgement: Food Code 4-101.13 limits are 1 mg/L for bowls over 1.1 L (1.16 qt) and 2.0 mg/L under; "lead-free" claims on traditional Mexican pottery have tested above FDA action levels (FDA Q&A).

## Script problems

- `validate.py` rejects `"vertical": "supplies"`, as on the other Supplies runs: the skill's `schema.json` enum is formulations, machines, fashion, furnishing, other. category.json keeps `supplies` as briefed, so validate reports exactly one problem (`schema  vertical: 'supplies' is not one of [...]`). A copy with `"vertical": "other"` validates clean ("valid. 12 facets, 3 splits, 21 references."). Because of that one error the brief's `validate && render && viewer` chain stops at validate, so render.py and viewer.py were run on their own; both completed without errors. Scripts and schema were not modified.
- Update 2026-10-25, after the blind check: the skill's schema now includes `supplies`, so `validate && render && viewer` ran as one chain and all three exited 0.

## Corrections

First pass 2026-10-25, before hand-over, after reading the draft against the sources:

1. material: "All three testers built their picks around steel and glass" replaced; Epicurious also has a plastic pick.
2. bowl_profile rationale: "All three testers found" narrowed to Wirecutter and ATK, with Epicurious confirming only the splatter half; an unsourced "halves what is left" removed.
3. largest_bowl_size: "uses 8 to 20 quart bowls to proof dough" restated as ATK's "great for proofing" line; split rationale no longer says the top band is only open-stock bowls, because Amazon shows sets reaching 7 qt.
4. weight_per_quart: "steel near 2 to 5" was true only at 4 to 5 qt; the band now says so, and the glass top rose to 18 to include Wirecutter's Pyrex.
5. Copper judgement: "protects foams from overbeating" replaced by a paraphrase of the abstract, whose word is "overheating".
6. Thin-steel trade-off: "the thinnest restaurant bowls" replaced, since the dented-on-arrival set (FineDine) was an Amazon set, not a restaurant bowl.
7. Branch dropped: `6 qt and up` makes glass_type irrelevant (Wirecutter names a 6-quart glass bowl).
8. Plastic family "typical for: kids" replaced; Wirecutter's kids pick is a rubber-bottomed steel bowl, not plastic.

## Corrections after the blind check (2026-10-25)

The blind check (`check.md`) listed 15 required fixes. All 15 were applied. None was rejected outright, but parts of three (5, 11, 12) were done differently from the checker's wording, as noted on those lines. Sources re-read this session: Epicurious, ATK 1538 and ATK 1650 by curl. Amazon (curl and WebFetch), Cuisinart (page, search and every sitemap in robots.txt) and FDA CPG 545.450 (page and PDF) all returned a block page or 404. WebSearch had no budget left.

1. double_boiler_ok: backfill none → low, still derived, now from material plus the researched non_slip_base or coating flag. Steel is yes only once a photo or brand page shows no coating or base, else unknown (ATK lists OXO's set as "Stainless steel with plastic coating and Santoprene base"). Copper and ceramic are unknown, not no. The "we treat steel as the safer pick" line was replaced: Pyrex bars direct heat, a water bath is not direct heat, and Wirecutter and Epicurious used glass that way, so glass is yes. non_slip_base backfill note now records plastic-coated exteriors too.
2. largest_bowl_size: values → under 4 qt / 4 to 5 qt / over 5 qt, which closes the 5 to 6 qt gap. The split rationale says the band edges are ours and that "bread" comes from ATK's extra-large proofing line. "household size" removed from skip_if_known (ATK: "even for a small household"). Wirecutter's hand-mixer link for 4 versus 5 qt added to why_experts_care. Branch `when` changed to `over 5 qt`.
3. real_bowl_count: no longer depends on bowls_in_set. It counts bowls of 1 qt or more from the size list or includes line (Epicurious's smallest useful bowl is "1–1½ quart"; ATK prep bowls are "usually between 4 and 8 ounces"). bowls_in_set is now all bowls of any size, source researched not derived, and its hint warns that some titles count bowls only (the checker's "6 PCS ... with 3 Grater Attachments" example, which I could not re-fetch, so it is not quoted in the JSON).
4. Scope: grater-lid, colander, measuring-cup and lidded bundles are kept in mixing-bowls. I confirmed the sibling scopes in graters/, strainers/ and measuring-cups/ notes, and confirmed that containers/ and storage-containers/ do not exist. Scope line rewritten; bowls_in_set backfill note says to count only their bowls.
5. Glass size cap: mechanism, glass family, glass trade-off and largest_bowl_size now say "most glass sets stop below 5 quarts", and the family says larger single bowls are sold. I used "below 5" rather than the checker's "4 to 5", because it needs no new endpoint: Wirecutter's 4, ATK's 4.5 and the checker's Amazon 4.8 all sit below 5.
6. Glass weight: bowl_weight says ATK and Wirecutter disagree on what appears to be the same Pyrex 4 qt bowl, and that Vollrath's spec puts its economy bowl heavier than ATK does. "ATK weighed" → "ATK lists". weight_per_quart glass band → 11 to 15, with Wirecutter's 18 named as an outlier.
7. Branch glass → then_ask glass_type removed. The hand-mixer caution was added to the glass trade-off ("hand-mixer use" in give_up) and the mechanism instead of a branch.
8. Branch over 5 qt → then_ask bowls_in_set removed. No set-versus-open-stock facet added: no listing field for it was checked.
9. Skip conditions: material → "stated material"; bowl_profile → "stated wall shape", and the rationale treats owning a hand mixer as a lean. Question reworded to "Deep for a hand mixer, or wide for gently mixing by hand?" (12 words), split and cold_start_question both.
10. Uncited claim: reference atk_prep_bowls (ATK Mini Prep Bowl Sets, 1650) added and cited in largest_bowl_size and real_bowl_count. Re-read verbatim: "despite the manufacturer's claims, the bowls in this set held only about 5 1/3 ounces, not 6 1/2". The number stays out of the JSON because it has one source.
11. Dead reference: cuisinart_ctg dropped from references, largest_bowl_size evidence and both hints. No replacement: every cuisinart.com URL and sitemap tried returned 404, and WebSearch was unavailable.
12. Regulator wording: the ceramic judgement now reads "FDA sets lead limits for ceramic food ware, restated in its Food Code for food establishments". CPG 545.450 is not named in the JSON because I could not read it (page and PDF 404). snopes_copper removed, and with it the pH 6 number (see the numbers table). The copper judgement now cites ATK on acid leaching copper plus the Food Code's "acidic food" wording. Melamine softened to "often not microwave-safe" in the vocabulary. That reading is supported by Epicurious ("often can't") and Wikipedia ("not microwave safe").
13. Plastic and microwave: microwave_safe now records the three-way split (Epicurious, Wikipedia, ATK "shouldn't be used in the microwave or with hot foods"). A new judgement, sources_disagree true, says the register filters on the maker's label and shows ATK's caution. The plastic → microwave_safe leg trace was updated.
14. Wording: "every bowl" → "each 4- to 5-quart bowl" over a 2-quart saucepan (Wirecutter). "melted chocolate in each" → "in each steel and glass bowl" (Epicurious, re-read: "we used the stainless steel and glass bowls as double boilers for melting chocolate"). "Copper is rare" → "rare in mass-retail listings" (ATK, re-read: "Copper mixing bowls are still widely sold"). bowl_profile evidence gained vollrath_69050, pyrex_8pc_spec and atk_vollrath_2023. Reference support lines were updated to match.
15. Backfill classes: steel_gauge medium → high, with near-zero expected fill stated. bowl_weight's heavy/light fallback removed; the field is left blank and the material facet carries that contrast. lids_included is settled as researched/low in both the JSON and the schema table, because a silent title does not mean no lids. bowl_profile's vision pass now has a reference-bowl rule: shallow like Pyrex 4 qt and Vollrath economy, deep like Cuisinart and Vollrath 69050, with ATK's "tall and wide" counted as deep (our call).
16. Knock-on fix, not in the check: the summary said glass is "the reverse" of steel, which implied glass cannot go over simmering water. That conflicted with fix 1, so it now says glass "microwaves but is heavy".