Supplier Guide
How to Verify Metal Cap Suppliers in China
Verify China twist-off cap plants on your jar, your fill, and a compound certificate that names this cap. A factory SGS sheet is not that proof.
Quick answer
Verify a metal cap supplier by sealing your jar with the quoted compound, under your fill process, and by reading a report that names that cap and that food. A company-level SGS file that does not name the gasket is not verification.
What must the sample prove?
Cap the production finish, or the finish you will buy, at the torque or vacuum your line uses. Then run the real thermal process and check vacuum loss, leakage, and ease of opening. A hand-tightened sample on a similar jar does not qualify hot fill or retort. If you need a safety button, record the panel position on good and failed samples. Keep retained caps from the approved lot.
Which document scope is enough?
Ask for the compound grade, metal type, and lacquer, plus a food-contact or migration report whose scope is that construction and your food category. If a supplier states SGS testing, ask which report number covers this diameter, this compound, and this food, and check the date. PackTrades does not store certificate scans for cap makers. Linyi Yinuo’s materials say products are SGS tested; that statement is not a report. Buyers confirm originals before a purchase order.
What should you confirm beyond the certificate?
Confirm who compounds or buys the gasket, whether metal and lacquer can be substituted without notice, and how caps are packed for ocean humidity. Rust on the curl after a humid lane is a packing and coating issue, not a print issue. A factory video can show forming and lining. It does not replace the seal test. Inquiries for plants listed on PackTrades go through PackTrades, not through a phone number copied from an old directory.
What belongs on the purchase order?
Write the sample result into the order so a later lot can be rejected against it.
Finish drawing; lug count; tinplate or tin-free steel; lacquer
Compound grade and the process temperature and time it was tested at
Seal-test method, accept criteria, and who pays for a failed resample
Report identity for food contact; substitution ban; packing method
When should you walk away?
Walk away when the plant will not cap your finish, will not name the compound, or treats a signed color proof as a substitute for a seal test. Also walk away when “high temperature” is not tied to a degree and a dwell you can put on the order.
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