hutch, yes, the gray unsanded is fine. but I'm forewarning you, you need to seal them before grouting. I don't care what your tile guys say. Why would you go through all the hassle of doing a grout release when if you just seal them, the grout won't stick to it? you have to seal them anyway, so why make extra work for yourself? Unless, they aren't sealing at all and expect you to do it. that makes more sense. they will do the least amount of work possible.
Grout will stain the white portion of an unsealed cement tile. 100%, it will discolor it. Trust me. I can't believe these tile guys don't know this.
If they are coming tmrw to grout, I would at least apply 1-2 coats tonight. Then they can still do their grout release before they start grouting. hopefully that should be enough.
read this post. her tile was not sealed and they did gray grout. look at what happened to them.
[https://www.houzz.com/discussions/cement-tiles-stained-by-grout-dsvw-vd~4922245[(https://www.houzz.com/discussions/cement-tiles-stained-by-grout-dsvw-vd~4922245)
read these sealing instructions from the place where I bought my tiles:
https://www.cementtileshop.com/INSTALL.html
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Cement tile advice
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