Don't know about grout boost.

Seal before grouting, being careful not to seal the sides of the tile at the spacing. I've been told that the grout wont stick. Then after it is grouted and dried throughly, seal again, going over both the tile and the grout as directed. Miracle 511 is highly recommended from post I've read. I have the penetrating type that I will use on my slate floor. I don't want enhancement of my stone. There are sealers that enhance the color as well.

Thank you for the reply. The accent tiles are a very small ( 1/2 inch) ming green and glass mosaic . It will be difficult to get the sealer on just the face of the tiles, but I'm sure it can be done. Can anyone suggest an easy way of doing this ?
Thanks again,
salbwil

I think just a cloth lightly saturated with solution would work, just not soaking. Wipe it on. I did this last year on my marble tile without issue. As long as it is not dripping I think you will be ok. Read instructions and follow. The reason for sealing before grouting is to help the grout not stick to the surface while grouting. Making cleanup easier. Maybe someone else will be more familiar with the tech.