Comparison
Tinplate vs Tin-Free Steel Twist-off Caps
Choose tinplate or tin-free steel twist-off caps by lacquer, cut-edge protection, and the fill—not by coil price. Confirm both on your jar.
Quick answer
Tinplate and tin-free steel can both make twist-off caps. Choose with the lacquer, the cut edge, and the fill, then confirm on your jar. Do not award the order to the cheaper coil, and do not treat the Chinese word 不锈铁 as stainless steel.
What is tinplate on a twist-off cap?
Tinplate here means electrolytic tin coated steel. The tin layer can protect steel exposed at a cut edge. That matters when the fill is acidic or salty and lacquer at the curl is hard to guarantee. Specify coating mass on each side if your quality team already controls it. State product chemistry so the plant does not default to the coil it slits most often.
What is tin-free steel, and what does 不锈铁 mean?
Tin-free steel (TFS), also called electrolytic chromium coated steel, uses a chromium/chromium-oxide layer instead of tin. Organic coatings and print generally adhere well. The cut edge still needs complete lacquer, because there is no tin to cover bare steel. On Chinese cap listings, 不锈铁 usually means this tin-free cap plate, not 304 stainless. PackTrades reads Linyi Yinuo’s 不锈铁 range that way. Confirm the substrate on the order.
When does the cut edge decide the metal?
The curl and the cut edge see the product and the retort water. Acid, salt, and sulfur-bearing foods punish a bare edge. Tinplate can be the safer default when edge coverage is uncertain. Tin-free steel can be the better print substrate when the lacquer system is already proven on that fill. Protein packs should ask for a sulfur-resistant internal lacquer either way, or the metal can darken even when the seal holds.
How should print follow the metal?
Litho is printed on flat sheets before the cap is formed. A paper or digital proof does not show adhesion, varnish scuff, or damage from knurling. Approve color on production metal of the same type you will buy. An anti-slip knurl or a higher skirt changes how the sheet is formed. It does not change the corrosion job of the lacquer.
How do you compare two metal quotes?
Compare a frozen bill of materials. One unit price is not a comparison.
Metal named as tinplate or tin-free steel, not “metal cap” or “stainless”
Internal and external lacquer; sulfur resistance if the fill is protein
Print on production metal; knurl or high skirt called out separately
Same compound grade and same fill temperature on both quotes
Corrosion and seal check on the real jar after the real process
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