While reading the Tile Letter (April 2009), I came across an ad for CBP's Prism Grout. The ad indicated "No color shading, no efflorescence, and stain resistant." I became curious because the bag on the ad looked like any other 25lb bag of sanded grout and not some epoxy product. I called CBP and reached Corey in the Technical Department who explained that this grout is a water mixed polymer modified ANSI A118.7. The reason for the added protection is an aggregate that does not consist of sharp graded sand but rather is small glass beads. The rounded beads allow greater compaction and density reducing water absorption and staining potential. According to Corey, this does not relieve the contractor or user of properly applying the material and sealing it adequately with a good quality penetrating sealer.

I just thought this was pretty cool. By the way, don't look for this grout at your big box stores. This grout is a contractor specific product available at tile centers only.