The 30W39B is a 38mm (38-400) black metal cap with plastisol liner. This closure is typically used on 38mm glass jars. The Plastisol liner is designed to create an air tight seal when heated. It is recommended for high temperature applications (container must be able to withstand high temperatures as well).
Electrolytic tinplate caps are highly sought-after metal closures that are sometimes referred to as tin coated steel caps, which are manufactured from 73 lb. - 80 lb. x .20 lb. electrolytic tinplate metal. The coatings on these caps are FDA approved and contain no heavy metals and the tooling meets ISBT standards. The metal itself has been sized, coated, varnished, and waxed. Tin plate steel is sometimes used in place of lightweight mirrors due to its shiny or lustrous like mirror appearance. Tin-plate steel is available in various color options such as, white, gold, red, and yellow and is more competitively priced than other options. Most tinplate steel metal caps are colored and have a uniform color and coating application on the closure surface area; whereas, tin coated steel caps need a protective coating because they can corrode easily.
This information has been provided as a general guide. It is the customer's responsibility to select the proper container for product and application compatibility.