I've just regrouted all around the bottom of our bathroom shower and the grout and dried unevenly. The grout has been drying for 3 days and each day the dark grout color seems to lighten a little bit but is patchy (light/dark/light/dark). We want to use the shower so I want to know if I put some sealer on the grout now, will it keep this patchy look permanently?
Being a shower at the floor/wall joint, I can assure you there is lots of moisture between the walls. It may take a long time for the grout to lighten. Matter of fact, since you used grout instead of caulk, it's likely to crack before then.
If your shower was built the way most shower are, (wrong). The moisture will not dry out because the base and wall substrates are saturated and can not dry since no air gets to them.
Sealing the grout has nothing to do with keeping water out, if that's what you were thinking. It's a maintenance thing. Sealer slow the absorption of liquids and stains, and that's it.
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.