westernrover
Member
- Joined
- May 4, 2018
- Messages
- 1,613
The buckets are high density polyethylene which has a some oxygen permeability, but they are thick enough they should work fine. Metal is the only practical thing that's better. You can get HDPE bucket lids with or without a gasket. Obviously, only the gasketed lids will seal. They will need to be malleted on and a lid opening tool makes getting them off easier. If you can't read between the lines, they're a b*tch. Be sure you don't need to access them often. Sealing with an internal liner bag could work but some liners seal poorly and others are easily damaged. Some kinds of plastic like PVDC could even cause tarnishing.
This chart: https://polymerdatabase.com/polymer physics/Permeability.html
Shows how PVDC is actually a wonderful moisture vapor and oxygen barrier, but unfortunately it gives off gases that cause tarnish. You can also see the high permeability of LDPE (common plastic bag material), and how HDPE is a little better while having no harmful effects. See this general guide: https://www.nps.gov/museum/publications/conserveogram/18-02.pdf
The brass should be completely dry before you seal it in or you are assuring tarnish and corrosion. Dry-tumbling after wet tumbling is a good way to make sure the brass is dry and you may still have your equipment. Otherwise, there are many ways to dry brass. Ideally, you want not only to remove the water, but also minimize the water vapor within the sealed container. Heating the brass and flushing the container with nitrogen gas before sealing would be good practice. Water is not the only thing that will tarnish or discolor brass. Instead of using common desiccants like silica gel, I suggest using activated charcoal pellets. They will not only absorb water vapor but they will also trap other tarnish-causing gas molecules like sulphur and chlorine compounds and formaldehyde (from wood or paper). Also, be sure to avoid sources of those kinds of compounds such as adhesive labels, stickers, paper, cardboard, etc.
