Several years ago I tiled bathroom floor and I recall one of the steps was
to keep the grout moist for several days by using a spray bottle and lightly
misting the joints. I'm no pro so someone must have told me it was a
Well, I'm doing some more tiling and I don't see this as a step in any of
the online guides I have read, no one in Lowes knew what I was talking about
and even talking to my sister who has the pros do her tiling said they don't
do this step.
So, what is the answer? Do I need to mist the grout or not?
I've been told (and have done) that misting for 3 days-2/3 times a day
helps to slow cure the grout and prevent cracking at a later date. I've
also heard that if you are using a colored grout that it is not a good idea
because the color will bleed and be inconsistant.
But that was also several years ago...
Grout, like concrete, is based on portland cement, which cures much harder
if it is kept wet for several days. But a lot of grout products these days
contain polymer additives that let you dry cure, which is why you may not
see instructions to keep it misted any more.
Our tile contractor told us to do that for ? three days, I believe. We
did. I guess it is to help the grout cure. They did a great job, so I
was anxious to do exactly as directed but can't recall for sure how long
Whilst true of straight Portland grout, almost all grout is modified
grout in this day and age. The latex/polymer additives add greatly to
the strength, bond strength and flexibility of the grout. Keeping the
grout wet while curing is important if it is an unmodified grout as the
grout will shrink and crack if it dries out too quickly. This is far
less of a concern with modified grouts.
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