The "5-Layer Coated" Frying Pans Started Peeling Within Two Months

Nonstick Pan Coating Layers, Thickness and PFAS Testing Guide

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A brand selling kitchenware online placed an order for 3,000 28cm induction frying pans with a cookware factory in Yongkang (永康), Zhejiang. The design was an aluminum body with a "5-layer nonstick coating" and a stainless steel induction plate on the base. The sample released a fried egg without any oil, and pre-shipment inspection passed everything: dimensions, base flatness, foreign particles and scratches on the coating, and the egg test. The product page said, in large letters, "5-layer coating that lasts."

In the second month of sales, the reviews changed. Photos kept coming in showing the coating lifting in thin flakes from the center of the pan, and silver aluminum showing through wherever the spatula had run. The brand sent leftover stock to a lab for cross-sectioning. The coating was about 18μm thick, half of the approved sample (about 35μm). And there were not five layers, only two: a primer and a topcoat. The factory contact explained: "五层是行业叫法，底油加面油也可以这么说 (Five-layer is just what the industry calls it; primer plus topcoat can be called that too)."

When a nonstick pan is new, the differences barely show. A thin two-layer coating still slides an egg out nicely for the first few weeks. The difference appears after dozens of rounds of cooking, washing and metal utensils, and by then the stock is already in customers' kitchens. This post covers nonstick coating types and layer structures, checks you can run on site and their limits, approximate criteria, gaps in PFAS claims and test reports, common supplier substitutions, and what to cover in the spec sheet and at inspection.

Words like "5-layer coating", "PFOA-free" or "ceramic" guarantee nothing on their own. Write the coating type, the coating brand and grade, the number of layers, total thickness and surface preparation into the spec sheet, then check thickness, adhesion, abrasion and fluorine content on samples pulled from mass production. That is what prevents peeling and labeling problems two months later.

1. Why Pans That Passed Inspection Peel Within Two Months

Most pre-shipment inspections look at the new product's appearance. Inspectors check that the coating color is even, that there are no bubbles or particles, that the base is flat and that an egg releases. A two-layer coating and a five-layer coating, an 18μm coating and a 35μm coating, all pass these checks equally. Nonstick performance comes from the topcoat, so nothing looks different when the pan is new.

What makes the difference sits under the topcoat. The midcoat resists wear through its thickness and reinforcing particles, and the primer anchors the coating to the aluminum. Drop the midcoat or cut the total thickness, and the base shows through as soon as metal spatulas and scouring pads wear down the topcoat. Skip the sandblasting that roughens the aluminum surface, or shorten the curing temperature and time, and the coating looks fine at first but lifts like a thin film after dozens of cycles of heat and detergent.

So the quality of a nonstick coating has to be judged by thickness, layer build-up, adhesion and abrasion testing. The principles of coating adhesion tests are covered in Episode 130, and thickness gauges for plating and coatings in Episode 141. This post focuses only on nonstick coatings on cookware.

2. Nonstick Coating Types and Layer Structure

Factory quotes mix many names: "不粘涂层", "特氟龙 (Teflon)", "陶瓷涂层 (ceramic)", "麦饭石 (maifan stone)", "钛涂层 (titanium)". Many of these are marketing names, not materials. Most "stone" and "titanium" coatings are fluoropolymer (PTFE) coatings with stone powder or ceramic particles mixed in to change the color and texture.

You also need to know the layer structure. A typical PTFE coating builds up a primer (底油), a midcoat (中油) and a topcoat (面油), and premium pans apply the midcoat two or three times to reach 4 or 5 layers. The trouble is that factories count "层" differently. Some count spray passes, some count coating types, and some count before and after curing separately. That is why the agreement should rest on total thickness and cross-section photos rather than the layer count.

Look at the body too. With the same coating, a pan pressed from rolled aluminum sheet and a die-cast pan differ in thickness and heat distribution, and a thin base creates hot spots that damage the coating first. For checking the aluminum grade, see Episode 157.

3. Checking Methods — From Hands-On Tests to Fluorine Analysis

Ask "几层涂层? (How many layers?)" and most factories just repeat the number in the spec sheet. The only way to verify it is to measure and test yourself, and each method has clear limits on what it can tell you.

Measure Thickness at Several Points

On aluminum pans, an eddy current gauge reads coating thickness in seconds. Measure each pan at the center, middle, edge and side wall, and record both the average and the minimum. Spray coating often leaves the center thinner than the edge, and the center is usually where peeling starts. Avoid the area directly above the stainless induction plate, where readings fluctuate.

Do the Cross-Cut After Boiling

Cross-cut a new pan straight away and almost any coating passes. Adhesion problems show up after heat and water, so you see the difference only when you immerse the pan in boiling water for 15 to 30 minutes, let it cool, then score the grid and pull the tape. Pans with skipped sandblasting or insufficient curing lose whole grid corners at this step.

"PFAS-Free" Can Only Be Confirmed by Fluorine Analysis

You can't tell by eye or touch whether a pan delivered as "ceramic" actually has fluoropolymer mixed in. If total fluorine analysis finds meaningful fluorine, a fluoropolymer is in there and the "PFAS-free" claim can't be used. Conversely, "not detected" in a PFOA-only test doesn't mean there is no PFAS, because many rules classify PTFE itself as a PFAS.

4. Approximate Criteria

These are condensed from coating manufacturer information and values commonly referenced in the industry. Results vary widely with coating grade and application method even at the same layer count, so set the actual criteria from your approved sample's measurements and the technical data of the specified coating.

Abrasion cycles are the number factories inflate most in their marketing. A claim like "30,000-cycle abrasion resistance" can't be compared with another pan unless it states the load, the pad type and the pass criterion (base exposure or loss of release). For finished products, it works better at inspection to write conditions and pass criteria together, like this:

• Coating thickness: Set both average and minimum, for example "average of center, middle and edge at least 30μm, no point below 25μm."
• Adhesion: Attach the pre-treatment, for example "cross-cut within ISO 2409 class 1 after 15 minutes in boiling water."
• Abrasion: Fix the test standard or the load, pad and pass criterion, then write "no base exposure after ○ cycles."
• Corrosion and heat: Match real use, for example "no blistering or lifting after ○ hours of salt water boiling" and "no discoloration or lifting after heating the empty pan at ○°C for ○ minutes."

5. Gaps in PFAS Claims and Coating Test Reports

PFOA is already banned under an international convention and EU rules, so "PFOA-free" is now effectively the default. Market attention is shifting to PFAS as a whole. Minnesota restricted the sale of cookware with intentionally added PFAS from 2025, and similar discussions continue in other US states and in Europe. Depending on the market and sales channel, sellers are increasingly asked for "PFAS-free" evidence, and just as often get into trouble for using the claim without basis.

Ask the factory for evidence and you usually get the coating supplier's FDA or LFGB report, or a "PFOA-free" declaration. The documents are rarely fake. The problem is the broken link between what the document covers and the pans actually being made.

Gaps in hazardous substance reports in general are covered in Episode 165, and import requirements for food contact products in Episode 64.

6. Common Supplier Substitutions

The coating may not look like a big share of a nonstick pan's cost, but dropping a layer and thinning the coat cuts both coating cost and curing time. Roller coating is much faster than spraying and wastes less coating. When price pressure arrives, factories start with what you can't see under the topcoat. Here are the patterns we have actually run into in consultations.

The most common pattern keeps the layer count while cutting thickness. "还是五层 (It's still five layers)" isn't a lie, so without a thickness requirement in the spec sheet you have nothing to argue with. The procedure for requiring prior approval of process changes is covered in Episode 119.

7. The Cost When the Coating Changes

Coating problems surface months after sale, and once they do, they spread to the whole lot.

• Reviews and returns: A review with a photo of peeling coating is the one other buyers look at longest. The seller pays for returns and exchanges.
• Health complaints: Complaints about coating flakes in food wear down a brand's image for a long time, whether or not there is real harm.
• Labeling and advertising issues: If claims like "PFAS-free", "5-layer coating" or "30,000-cycle abrasion resistance" are untrue, they can turn into advertising law problems, and abroad they breach the sales market's rules.
• Stuck inventory: The rest of the lot becomes stock that is hard to keep selling and hard to send back.

For recalls and product liability, see Episode 53; for claims and disputes, Episode 36.

8. What to Put in the Spec Sheet

Each factory reads a single line like "五层不粘涂层" differently. Put the items below into a table and attach it to the spec sheet.

The single most effective item is total thickness written as an average and a minimum. One gauge confirms it on the spot at inspection, and fewer or thinner layers show up as a number. For writing spec sheets and BOMs, see Episode 59.

9. Adding Coating Checks to Your QC Checklist

Sample Stage

The sample stage sets the baseline. Cut one approved sample to confirm layer count and per-layer thickness in cross-section, and use another to record thickness by point, cross-cut after boiling, abrasion and salt water boiling results. If you plan to sell as PFAS-free, run total fluorine analysis at this stage. Seal the approved sample with the date and item number so you can put it next to production units later. Sample management is covered in Episode 34.

Production Stage

On coating days, get photos or video of the coating can labels, the spray booths and the sandblasting equipment actually running. Asking for curing oven temperature records also helps. For tracking production progress, see Episode 102.

Pre-Shipment Inspection Stage

The inspector picks packed pans, measures thickness by point and compares with the sample records. A few pans get a cross-cut after boiling, and weight and base thickness are checked too. If thickness is borderline or adhesion looks doubtful, seal random samples and send them to a lab for cross-sections and abrasion tests. Pre-shipment inspection is covered in Episode 100.

10. Sample Request Wording for the Factory

Putting the wording below in your purchase order or spec sheet takes coating choices out of the factory's discretion and makes responsibility easier to assign if something goes wrong.

"本产品不粘涂层须使用规格书指定厂家及型号的PTFE涂料，底油、中油、面油共不少于三层，采用喷涂工艺，不得改为辊涂。涂层总厚度：中心、中部、边缘平均不低于30μm，任一测点不得低于25μm。喷涂前须进行喷砂处理，烧结温度和时间须符合涂料厂家要求。如需更改涂料、层数、涂装工艺、烧结条件或锅体规格，须提前书面确认。生产时请提供涂料桶标签及喷涂线的照片。出货前由我方从成品中随机抽样，进行涂层厚度测量、沸水煮15分钟后百格测试及重量、底厚确认，如不合格，整批返工或退货，检测及物流费用由供应商承担。"

11. Three Real Cases

These are anonymized patterns we often see in consultations. Amounts and figures are examples.

Case 1 — An Online Brand's Induction Frying Pans

This is the case from the opening. The purchase order said only "五层不粘涂层" with no thickness or application method. The factory held to "five-layer is an industry term", and only after cross-section photos of the approved sample and production units were laid side by side did it settle by partly compensating through a lower price on the next lot. The brand absorbed the exchange costs for units already sold and pulled the "5-layer coating" wording from its product page. Its spec sheets now list the coating per layer and the average and minimum thickness.

Case 2 — A "PFAS-Free Ceramic" Cookware Set

A seller sourcing ceramic-coated pot sets from a factory in Jieyang (揭阳), Guangdong, was asked for PFAS evidence when joining an overseas sales channel. The factory sent only the coating supplier's "PFOA-free" declaration, and total fluorine analysis on the finished product found a substantial amount of fluorine. It was a ceramic-looking hybrid coating. The factory said "陶瓷涂层就是这种 (That's just what ceramic coating is)", but the spec sheet had no "no fluorine added" requirement. Listing on that channel was postponed, and from the next order the seller added a no-fluorine clause and total fluorine analysis on finished product.

Case 3 — A Wok That Blistered in the Dishwasher

A company importing woks from Wuyi (武义), Zhejiang, started getting returns from the third lot saying "after a few dishwasher runs the coating bubbled up like blisters." Thickness was similar to earlier lots, but in a cross-cut after boiling, whole grid squares came off. A factory visit found the sandblasting equipment had been broken for weeks and the factory was relying on chemical cleaning alone. Had they measured thickness only, they would never have found the cause.

12. Common Mistakes

The most common is frying an egg in a new pan and calling it checked. The egg test shows only the topcoat, not the layers beneath it. We also often see buyers promising a layer count without a thickness, cross-cutting a new pan and calling it a pass, and using a coating supplier's "PFOA-free" declaration as PFAS-free evidence. Many measure thickness at a single point in the center, but results change with position, so fix the measurement points in advance.

13. Nonstick Coating Control Checklist

Sample Stage

• Coating type, coating per layer, layer count, average and minimum thickness and surface prep are in the spec sheet
• Actual layer count and per-layer thickness confirmed by cross-section of the approved sample
• Thickness by point, cross-cut after boiling, abrasion and salt water boil results recorded
• (If selling as PFAS-free) total fluorine analysis done on finished product
• Approved sample sealed and stored

Production Stage

• Photos of coating can labels, the coating line and sandblasting equipment received
• Curing conditions and application method confirmed against the spec sheet
• Coating, layer or process change requests applied only after written approval

Pre-Shipment Inspection Stage

• Coating thickness by point measured on randomly selected finished pans and compared with the sample
• Cross-cut after boiling water treatment done
• Weight and base thickness checked
• Coating claims on product pages and packaging match the spec sheet

Final Thoughts - Check How Thick the Coating Is, Not Just Whether the Egg Slides

Pans leaving the factory look equally smooth and release an egg equally well, whether they have two layers or five. The difference shows up in customers' kitchens after dozens of rounds of cooking and washing, by which time the whole run has already been sold. Writing the coating type, coating products and thickness into the spec sheet, and checking thickness and adhesion on samples from production, costs far less than the exchanges and returns you'd pay for later.

There is something you can do right now. Ask the factory currently producing for you to send the coating product names per layer, the application method and photos of the coating cans. If all you get back is "放心，五层的 (Don't worry, it's five layers)", put together a coating control table and send it before your next order.

StartMade supports you from writing spec sheets with coating type, coating products and thickness, through reviewing supplier coating documents and checking the coating line during production, to pre-shipment inspection including thickness measurement and adhesion checks. If you have already had peeling problems, we can start by analyzing remaining stock; if you are preparing new cookware, we can start with the spec sheet.