I haven’t started my build yet (wife won’t let me start until my u-boat and WWII cruiser are finished), but I have learned a lot from all of the experts here. While this is probably more than you metal heads ever wanted to know about epoxy, I hope you find it useful. I learned a lot the hard way and then I discovered
http://www.westsystem.com which has great products and great overviews regarding the use of epoxy. Whatever you use, note that not all epoxies are created equal.
5-minute epoxy isn’t used for parts that will be submersed because it’s not as waterproof as longer cure time epoxies. While I haven’t tried it, soaking in water overnight might soften the former but it will likely have zero effect on the later. Keep in mind that many epoxies will actually cure in water.
The best way to remove cured epoxy is to use a heat gun to soften it (200°F) and scrape it off. Make sure that you have good ventilation. As you point out, that’s probably not be the best approach given the rubber tires.
You might also consider the type of epoxy that you use. There are epoxies that are designed to join dissimilar materials to better deal with the different rates of expansion, contraction (i.e., West Systems G-Flex). Think about the diameter of the metal wheel baking in the sun vs. the thin rubber wheel. These products are more flexible than standard epoxies, but much stiffer than adhesive sealants.
Curing epoxy goes through three states; liquid, gel (a.k.a. initial cure) and solid. When it progresses from a tacky, gel consistency to the firmness of hard rubber (i.e., you can dent it with your finger nail) you can usually remove excess epoxy by using a razor blade to lift up the edge at which point you can just peel it off with your fingers, tweezers or needle nose pliers. How long the epoxy takes to get to and remain in that state depends on the type of hardener and room temperature. It can be as little as a few minutes or, if you screw up the ratios, days – don’t ask me how I know;-) That’s why I usually mix a small batch first to ensure that I have everything right… keep in mind that some epoxies are 1:1 whereas the stuff that I like to use is 3:1.
You asked “if it was good enough to stick the first time could you just reapply for a second time.â€
