Will all epoxies bond to one another? I have some West GFlex, which I
want to use thickened to fill a gap between two loosely-fit fiberglass
parts, and some System Three laminating resin (Clear Coat, I think, I
don't have it with me right now) that I then want to use with glass
tape to reinforce over the surface of the joint. Will the epoxies
bond well to each other, if the glass is applied within a few days of
the first resin?

Also, is colloidal silica and microballons the same? I have an old
bag of house-brand microballons from Fiberlay, and colloidal silica is
recommended as a thickener. I feel like I used to know the answer to
this...but, apparently, I'm an idiot!

Thanks,
Mike