I was wondering if anyone here had any experience with crystalline waterproofing products good or bad? There are perhaps half a dozen brands ( Xypex, Kryton, Penetron, etc) and all of them seem to work by growing crystals into masonry through the existing pore spaces. I'm leaning towards the Xypex myself, (although I don't have a price yet) and wondered how other people had done?

I would be applying it to an existing wall, not mixing it into the cement before construction.

Thanks, folks!