I bought this 1984 SteelBelted Cooler new and since then it has accumulated a lot of mileage. The dents and rust are part of its character and don’t affect its function. On other coolers of this type I have replaced the hinges and handles, even replacement locking mechanisms are available on ebay and from the manufacturer. This cooler’s weak spot is the waterproof bottom. The plastic becomes brittle with age and the corners crack and tear. For todays repair I will be fixing a couple of corners so that they will give me a few more years.
There is foam inside the plastic bottom, which gets brittle and leaves voids. So the voids need to be filled and then the scar covered with a waterproofing.
First inject urethane foam into the gap. As urethane foam dries it expands so I wrap it in a plastic bag and apply pressure, for small gaps, I use some Gorilla tape, for large corner gaps, I wrap a strap clamp (or use some rope) and the void will keep it’s shape more or less. It doesn’t matter how much leaks out of the scar, the foam is brittle and can be removed, the trick is to make sure all of the void is filled and the bulge isn’t TOO far out of shape. A little bulge from the original shape is to be expected.
After it has dried under pressure for about a day, I carve away all the foam from the outside and then sand it back into shape.
After sanding I add one thin layer of bathroom silicone tub caulk. This isn’t adhesive enough to fill the gap on its own, but it is just right to smear over the repair and protect the foam from breaking up. When it has dried you can sand it smooth again if too lumpy, I like to go back and dab more on and give it a textured finish which resembled the original.
This is one of the less damaged corner tears. There is a much worse corner which took another day and a half to complete as I had to use tools to dig out the rusty metal to give me a clean void to work with. But I think I can get another 34 years out of this one.