polymer-modified mortar and ad-mix added to standard mortar are
basically the same thing. The modified morter is a little less messy
to work with in my opinion.
And I wouldn't go to the trouble of using epoxy grout unless
you have a situation where extreme protection is needed.
It is very difficult and un-forgiving to work with compared
to standard grout with a latex additive.
The admix is used to increase bond as it uses the admix instead of water. Because it is in a stonger bond it may be usefull for a tub/shower surround or perhaps a tile on tile application. I dont think for the kitchen backsplash you really have to worry....A good modified thinset would be fine.
As for epoxy grout, they are, as stated by jbob, a pain in the ass to work with...with one big exception in my opinion...Spectralock. Stainproof, you never need to seal it, the look is flawless and it is surprisingly easy to use. You can even freeze what you dont use and break it out later, let it sit for a little while and then reuse. The drawback, of course, is that it is expensive. Lowes carries it. I dont think it would be necessary for a backsplash because they just dont take much abuse...but for a surround and definetly for floors it is ideal.
Hope that helps
"What if the hokey pokey really IS what its all about."
Last edited by dougrus; 11-24-2006 at 10:17 PM.