I've been putting together BU solid date rolls of zinc 1983-2018 Lincoln cents. Now I want them to stay BU and not rot like ones I have seen posted here. What would be the best way to do this?
I'm not sure anyone has a foolproof way to do it for the very long term. If I didn't detest Zincolns, here's what I'd do: 1) Find a workspace with very low humidity. 2) Rinse the coins with distilled water, then acetone, then acetone again. This will remove anything water-soluble, then remove the water itself, then remove any grease or oil. 3) Put them into clean, dry polyethylene tubes (the white square ones, not the clear round ones). These tubes seal pretty well. 4) Put the collection of tubes into a sealable box with some silica-gel packs to absorb moisture. 5) Put the box somewhere where there won't be big fluctuations in temperature or humidity. This also implies keeping it indoors, out of sunlight, and not in a basement or attic. If the temperature rises and falls, it increases the risk of moisture condensing on the coins. I'm still not sure this will save Zincolns from everything that's wrong with them, but it's about the best you're likely to do without going to extremes. (I consider "purging the containers with dry nitrogen and then fusing them shut" to be extreme, but that would be more likely to work.)
One thing to add to what jeffb said, check them every few months and make sure the silica gel isn't saturated (If the box is well sealed that shouldn't happen for a long time. Us an indicating gel so you can tell, preferably without having to open the box.) The key will be to get the humidity as low as you can and keep it there. Most toning or corrosion reactions are oxidation reduction reactions and they require water to proceed. Eliminate the water the reaction greatly slows or stops. Water vapor in the air is enough to allow the reactions so the dryer the air the slower the process. You could also put the tubes inside a sealable bag before you put them in the box. The more barriers between the air and humidity and the coins the better. Defense in depth.
Oh, no, that's probably not a good idea at all. Most paper contains sulfur compounds, which will discolor almost any coin over time. If you have everything dry enough, they might not make your cents change color, but it's a bad bet.
I would put them directly from paper tubes into plastic tubes with a screw-top lid. I would screw it closed, but not tight. Then I would put several rolls into a vacuum pack bag with a few silica gel packets and vacuum seal it. Then store them in a room with constant heat and humidity - like a closet in a bedroom that doesn't have an attached bathroom. I would leave the surfaces original - don't rinse them with anything.
