Tips for Grout Issues from CMA

This was in an email sent to members of CMA (Contemporary Mosaic Art) website…

A message to all members of CMA

CMA Member News Reporter

Submitted by Tricia Huffman

May 14, 2011

Grouting Continued..

Since this is the finishing touch to your hard work, I am expanding on the issue of grout issues from last report to address some questions that came to me as a result.
I went to the experts whom manufacture these products, with my questions about it; here is what they said. “Over mixing or adding too much water to the mix would indeed weaken the strength of the grout joint and cause pin-holes and possibly efflorescence. If mixed according to manufacture instructions, adding more dry grout would not be needed. ( Though some artists use this technique when water supplies are limited, and have claimed great success with it.)
As far as using pigment to over-colour cured, unsealed ,non-epoxy grout joints, he indicated that using dry (French) pigments mixed with a tiny amount of water would indeed be permanent, and would have the same effect as grout stains currently on the market .
The last issue to address this month would be efflorescence, which is a white, chalky haze that sometimes appears on grout after it has cured. Here is a list of some of the causes.
1. Too Much Water was used when grout was mixed.

2. Concrete substrate had not fully cured or had a moisture vapor issue prior to adhering mosaic.

3. Water used in mixing or cleaning the grout was high in chlorine or had a high mineral content.( Pond water or home water softeners and city water that is heavily chlorinated or has a high mineral content can contribute to efflorescence.)

4   Temperatures were too cold while grout was curing.

5. Grout joints were wiped excessively during initial cleanup.

6. Standing water was left in empty grout joints prior to
grouting.

7 Tile was especially dense and nonporous.

8 Grout was prematurely exposed to heavy amounts of water before it had a chance to cure.

Always consult manufacture instructions for your particular needs.

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