Using old grout.

I have been maintaining a friends tile floor. It wasn't a first rate
job to begin with but it was adequate. About once every three months
he has me come over and patch where the grout has cracked and fallen
out. I have been using the bag of grout that he had left over from the

Yes, it does go bad. Grout cures because it undergoes a chemical reaction with
the water that you mix into the powder. (The same is true of plaster of Paris,
mortar, cement, plaster, etc.) It undergoes the same chemical reaction, albeit
at a slower pace, with water *vapor* that is present in the air. That reaction
happens only once -- in other words, after the grout has been exposed to
humidity for any length of time, it's no good any more. There's no practical
way to rescue the grout you have now; the best you can do is replace it. To
prevent the problem from recurring, store the unused grout in an airtight
container. That won't make it last forever, but it will extend the shelf life
considerably.

A bag of cement will harden over time.... Any good tile place will
have color sticks to let you pick a grout color. I put in some teal
green some time ago - yes the left over stiffened up and is disposed
of.

Oren
"My doctor says I have a malformed public-duty gland
and a natural deficiency in moral fiber, and that I am therefore
excused from saving Universes."

original installation. I would go out and buy more but it was a some
what unusual pink color. What I have been finding lately is that the
grout doesn't set up poroperly. It looks OK but it is soft and can be
dug out easily with a knife. Does grout go bad sitting in the bag?
It has clumped up some.