There isn't really a good way to reseal canned food. So I designed a simple silicone lid that will tightly fit over the top of a standard can. This silicone lid helps to keep the contents sealed until the next time that you need them. Here is how to make one.
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Step 1: Select a Food Grade Silicone Putty
The easiest material to use for this kind of project is silicone putty. This is a common material used for making molds. The brand that I am using is "Silicone Plastique." It can be purchased from MakeYourOwnMolds.com. Other silicone putties can also work. Just make sure that it is rated as "Food Grade."
Silicone putty typically comes in two parts (Part A and Part B). Each one by itself is soft and has the consistency of Play Doh. But when they are combined, they quickly cure and harden.
Before working with any silicone putty, you should read the material safety data sheet. This should let you know if there are any health hazards associated with this product and what safety precautions you should take. In most cases you will at least want to wear gloves while working with it. Also keep in mind that the silicone putty can stain some work surfaces.
Step 2: Select a Can
There are several different sizes of cans that are commonly sold. Condensed soups, vegetables, and fruits are all different sizes. So select one that you eat frequently.
Remove the label from the can. If you get any paper stuck to the silicone, it won't be able to make as good of a seal later.
It is easiest to work with cans that do not have a tab or a pop top. The tab can make it more difficult to cleanly separate the silicone lid from the can after curing. If your can does have a pop top, it is a good idea to remove it. You can try to cut it off with wire cutters or carefully pry it off with needle nose pliers. Try not to deform the lid in the process.
Step 3: Mix Part a and Part B of the Silicone Putty
When you are ready to make lid, put on your gloves and open up the tubs of "Part A" and "Part B" of the silicone mix. Scrape out an equal amount of each part. If you want to be exact you can use a digital kitchen scale. I used 38 grams (1.34 oz.) of each part. If you do not have a scale, you can also measure each part by volume using measuring cups.
Quickly mix the two parts together thoroughly. Once they are combined you will only have a few minutes to work before the putty starts to set.
Step 4: Apply the Silicone Putty to the Can
Apply the silicone putty evenly all around the top of the can. You don't want any part to be too thin or it might tear when used. The putty should come down the side of the can at least 1/2 of an inch. If you want to make sure that it has a smooth and even finish, you can gently go over it with a flat object such as a ruler.
Once you are happy with the shape, let it sit until it is fully cured. This brand of silicone putty cures in about 1 1/2 hours at 70 degrees Fahrenheit (21 degrees Celsius).
Step 5: Test the Putty to Make Sure That It Is Fully Cured
Before you attempt to remove the silicone from the can, you should test it to make sure that it is fully cured. Gently press on the silicone with the side of a coin. If is leaves an impression, then the silicone still needs some more time to cure. If the silicone is firm and bounces back, then it is probably safe to remove it from the can.
Step 6: Remove the Mold
Now it is time to remove the silicone lid from the can. Start by carefully separating the bottom edge from the can. Then gently lift up the sides. Slowly pull the lid up and off of the can.
Step 7: Wash the Mold With Hot Soapy Water
Before you can use your new silicone lid, you need to wash it with hot soapy water. Gently scrub all the surfaces with your fingers. Then dry it off.
Step 8: Cut Off Any Excess Silicone Around Sides
You only need about 1/2 inch of silicone coming down on the sides. If you have much more than this, you can use a sharp knife to trim the sides. This will also make a nice clean edge.
Step 9: Use the Mold to Reseal Canned Foods
Now you have a food grade silicone lid that you can use to reseal cans. Just slide the lid over the top of an open can and it should keep the contents sealed until the next time that you need them.
Keep in mind that by just opening the can you have already introduced bacteria to the food. So keep it refrigerated and use it within a few days.
Step 10: Cleaning and Sterilizing the Silicone Lid
Look up the procedure for cleaning that is best for your silicone putty. The putty that I am using can safely be washed in a dish washer or sterilized by dipping it in boiling water.