*Preventing Rust on Canned Goods*
24 January 2017
In the southern part of the U.S., with our humidity and marine salt, it's sometimes difficult storing canned goods, long term. As a sailor, I've had luck extending the life of metal cans by coating the outside. I also found it helpful when storing food in less than ideal conditions - like the house crawl space, etc
I've been trying several different methods in the past few years. If you decide to do this, give special consideration to cans opened with a can opener that may allow material from the outside of the can to come in contact with food.
Cans seem to rust first at the seams, mostly where the top and bottom meets the side. At home, I don't find many problems with the side seam. On the boat, I am sure to remove the label and coat the side seam. Start with a clean, rust-free can.
PARAFFIN WAX: This is my favorite method. I use Gulf Wax, the kind used in canning and preserving, although, the USDA does not recommend use of paraffin in home canning. According to my 1999 copy of the Complete Guide to Home Canning and Preserving, Second Revised Edition, "Because of possible mold contamination, paraffin or wax seals are no longer recommended for any sweet spread, including jellies." (p. 32)
Gulf Wax comes in 1 lb boxes. One box coats about five cases (60 cans) of fruit and vegetable cans. Find it in the canning supplies section of your supermarket. Melt wax in a double boiler. Make your heat the lowest heat possible to keep it liquid - don't get it boiling. WARNING: It is flammable if exposed to open flame. Never melt directly in pan over fire, hot plate or in hot oven.
Either (1) leave the paper on the can and dip one end into the wax, just enough to cover the seam. Allow it a few minutes to set on a wire rack, then turn it over and dip the other end. (Wax doesn't "dry" as there is no liquid in it.) Don't hold the can in the wax, just a quick dip will do. It tends to flake off if applied too thick. Else, (2) another strategy is to remove the paper, label the contents with a marker and brush wax all over the entire can. Before opening, I use a fingernail to scrape the wax from around the opener's path in attempt to keep most of the wax out of the food. But if a little does fall in, it's no problem. Gulf Wax is food-grade and food-safe, so it is edible. I actually tried it. No taste, just a little chewy.
MINERAL OIL: Use only food or medicinal grade mineral oil. You must remove paper labels and label contents with a marker. Wipe down the outside of each can with just enough oil to leave sheen. Although very successful, I don't care for this method because dust adheres to the oil on the can. So, be sure to wash the can thoroughly before opening.
PASTE WAX: This is not food grade. You must remove the paper label. Just wipe it on, as you would cover a car. I used this method on a large can of olive oil. (The olive oil had a pouring spout so there were no worries about contamination. I was happy with the results.
SILICONE SPRAY: This is not food grade. Spray a light coating, allow to dry, and then remove excess with a cloth. This worked well for me but it's relatively expensive with a lot of waste due to the overspray.
Be aware that come cans sometimes rust from the inside. Tomatoes and other high acid foods continually react with the container. Over the years, this can cause taste and texture to change and eventually the can will fail even after the outside has been coated.TooshieGalore
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