For a tiling job, I used this charcoal grout:
After a few days, as indicated by the instructions, I applied this sealer:
A few minutes after applying the sealant, these white stains appeared randomly in the grout:
It's been a few days and the stains are still there. What should I do about them? They tend to vanish if I scrub the grout, but I'm not sure that's what I'm supposed to do.
As suggested by @Ecnerwal, I wrote to Custom Building Products' customer support. Got a reply within 15 minutes:
The isolated areas look to be a bit of sealer residue that might not have been wiped or rubbed dry with dry paper towels after each application within 3 minutes of each application?
If so, this can be safely scrubbed off at any time, using a MIXTURE of baking soda, and water into a paste, and using a toothbrush, the white surface residue can be scrubbed off without damaging the sealer protection or original grout color.
There is no need to re-seal the grout.
Did you use all the grout at once? Some grouts aren't dry mixed well at at the factory. If you read the fine print it will say to mix the dry grout BEFORE adding water to.
So if you do it in batches and didn't mix it, you'll get uneven results. When you wash it, it's just getting wet and hiding the problem.
