You can use plasti dip, it is essentially spray paint that dries as rubber. It's a bit of chore to apply, you have to tape the whole shoe aside from what areas you want to protect. You also need to to 3-4 coats minimum. It's a bit of a pain actually and i found it blows out faster than shoe goo. My advice is make sure you put the lid on tight for shoe goo or just buy New when it dries out its relatively cheap.