I'm working with a team that is selecting the packaging for a few food products. We're considering using metal lids that are made of tin.
From what I've read, it sounds like tin is fairly non-reactive. However, everything I found so far was rather vague.
Here's an excerpt from one of the articles I read:
"Tin is attacked only slowly by dilute acids such as hydrochloric acid (HCl) and sulfuric acid (H 2 SO 4 ). Dilute acids are mixtures that contain small amounts of acid dissolved in large amounts of water. This property also makes tin a good protective covering. It does not react with acids as rapidly as do many other kinds of metals, such as iron, and can be used, therefore, as a covering for those metals. Tin dissolves easily in concentrated acids, however, and in hot alkaline solutions, such as hot, concentrated potassium hydroxide (KOH)."
QUESTION: Can you tell me if tin would react or leach in any way if exposed to slightly acidic food products (with an approximate pH of about 3.5) or slightly alkaline food products (with an approximate pH of about 8)?
Thank you so much for your help on this!
The short answer is YES, it will leach into the contents eventually. That is why modern canned goods usually have a thin plastic layer applied to the inside surfaces. It is a matter of degree and time. Coating iron with tin, or using tin directly will reduce the rate of dissolution, but it never stops it completely. SO, for limited storage times, it would not likely pose any particuar problem But for longer contact times and eventual use in food products, the inclusion of tin in the contents must be assumed, as well as the gradual deterioration of the container material.
Thank you very much for your thorough answer! It is greatly appreciated!