(Big Spring, TX)
After allowing the grout to cure, I applied a grout sealant.
The next day I noticed that some of the grout lines now had indentions or small holes.
Did the sealant cause this damage?
I am about to seal a second floor and a shower and want to avoid the same problem.
How long did you wait before sealing the grout? Usually grout manufactures say allow 48 hours of cure time before sealing.
Most of the time tile contractors will seal grout 24 hours after they apply grout.
I've never seen the seal have any adverse reaction to grout.
It could have been from the grout mixture itself, but this is only speculation.
I would wait a few day before sealing the other areas to see if these bubbles appear again.
This would give you an indication if it's from the grout or from the sealer.
My bet is on the grout itself and not the sealer.
These are only my opinions and based on my experience with sealing new installations.
I hope this helps.