I looked into a Goex 4F powder can to see how much powder was left and saw corrosion. After emptying the 295 grains that was left, I looked with a borelight and saw the entire interior was corroded. The walls were rough textured but the bottom had bright spots in it, almost like small shotshell pellet strikes on a steel plate, free of corrosion. The exterior is perfect and the can has never been wet. The powder is normal. This is Superfine Black Rifle Powder from Goex at Moosic, PA. The lot number on the bottom is 04-46/79JU08B, all numbers are not clear, but I think that is correct. I looked into another Goex 2F empty can and it was perfectly shiny. Guess I'll have to check all the rest of my empty cans.
The packing codes shows June 8, 1979.
GOEX, prior to mid 2000, was made using a fertilizer grade of potassium nitrate that contained about 0.5% of sodium nitrate. Sodium nitrate goes beyond hygroscopic. It is actually deliquescent. Meaning it will pull enough moisture from the air to dissolve itself and form a solution. That small amount of sodium nitrate produces an effect in the powder far out of proportion to the actual amount. How much moisture (water) is picked up out of the air depends on the grain size. Smaller grain sizes gave a more rapid and more extensive pick up of moisture.
The tin cans used by GOEX were produced here in the U.S. Electroplated, not hot dipped. Single coat. Tin coatings are noted for being porous. Old "dairy tin" used in
milk producing farms was triple hot dipped to eliminate the porosity problem. With the 3 dip coats no two pores lined up with each other completely through the tin film.
Up until the advent of synthetic polymer solution resins food producers would not pack any sulfur bearing food in tin cans. Tin plating does not offer good protection of the substrate steel when the contents of the container (can) contains any sulfur. Even in trace amounts. traces of sulfur vapors/gases will penetrate the pores in the tin coating and react (corrode) with the base steel.
The difference between the 4f can and the 2f can relates to grain size and amount of direct contact between the powder grains and the inner tin surfaces of the can. In addition. Some lots of GOEX out of the old Moosic plant were more corrosive than others.
In 2000 GOEx was forced to look for another source/manufacturer of potassium nitrate. Production of potassium nitrate ceased in the U.S. that year. They then had to switch to potassium nitrate imported from Chile. Far superior to their old supplier, the now defunct Vicksburg Chemical Company who operated a potassium chloride conversion plant near Vicksburg Mississippi.
If anybody plans to save tin powder cans as collectors items you transfer the powder to some other container than rinse the inside oof the can good with warm water and then allow the interior to dry well.