Okay, I bought some Bondo to fill the gaps in a couple pieces. I read the can and it says to mix 1/4 tube (hardener) with 1/4 of the can contents. I've never used this stuff before and I don't want to get the proportions wrong. Would it hurt to just mix the whole can? How fast would it cure? This may be a stupid question, but I don't want to screw it up. Thanks.