How do you keep the Thin-set Mortar and Grout from Setting Up Too Fast?


In an Air conditioned environment how would you keep thinset mortar and grout from Harding or setting up to fast, is the something you can add to the mixture to prevent this from happening.


ANSWER - What you are referring to is the Pot-Life, which refers to how long the mortar stays workable inside the bucket, and Open-Time, which refers to how long the mortar stays workable as you install the tile to its substrate.

Actually, the air conditioning cooler air will extend the pot-life and open-time of the mortars.  It is the warm temperatures that will accelerate the curing of the mortars.

During the summer in hot climatic areas the manufacturers produce a "Hot Weather" version of their mortars by adding additional chemicals to it that retards the curing.

Wind can accelerate the curing of mortars so you need to make sure nothing is blowing on the areas you are working.

It is never recommended to add additional chemicals to mortars that the manufacturer hasn't provided themselves, as you could compromise the mortar and loose the warranty.  Always ask the manufacturer for their recommendations and use their products.

The key to controlling the curing of the mortars is to protect them from the heat, rain, cold, and wind.  The products do have limitations.  You might have to provide shading and air-conditioning in hot weather conditions.  In cold weather you might have to add heating.

If the mortar is setting off too fast, then use cold water to add to the mortars.  Or when all else fails just mix smaller batches of mortar at a time, enough to cover the area that will not set up too soon.  Also make sure the surface you are adhering to or the tile you are grouting isn't too hot.  Cool it down.

2 thoughts on “How do you keep the Thin-set Mortar and Grout from Setting Up Too Fast?

  1. Martine Allard says:

    MY sanded grout that I used, looks gritty after it dried.
    What can I do?
    Can I use unsanded grout for outdoors projects?

    • Donato Pompo says:

      Sanded grout is suppose to be textured. The sand in it makes it stronger and less resistant to shrinkage cracking.

      For grout joints 1/8″ wide or less you can use unsanded grout. Grout joints for 1/8″ wide or larger you should use sanded grout.

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