How to mix thin set mortar

Written by sue-lynn carty
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Thin set mortar contains latex, which allows it to be more resilient to everyday wear and tear. These additives also make thin set mortar more flexible, which is important because changes in room temperature cause the expansion and contraction of floor tiles and the subflooring below them. Without this flexibility, the tiles will crack. If you don't mix thin set mortar correctly, the latex properties in the mortar will weaken. This not only compromises the bond between the tiling and the subfloor but also the protective properties of the latex additives.

Skill level:

Things you need

  • Bucket
  • Cool water
  • Mortar
  • Measuring cup
  • Mixing tool
  • Latex gloves

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  1. 1

    Fill a bucket with cool water until it is about one-fourth full.

  2. 2

    Measure the mortar. Add it to the water slowly to kick up the least amount of dust possible. Stir frequently to check consistency.

  3. 3

    Mix thoroughly with a mixing tool. Slowly work the mortar and water in circles, being sure to scrape the sides and bottom of the bucket.

  4. 4

    Check the consistency. Keep stirring the mortar and water until it is the consistency of creamy peanut butter or frosting.

  5. 5

    Add a little more water to thin mortar that is too thick.

  6. 6

    Leave it alone. After mixing the mortar to the proper consistency, let it sit for five to 10 minutes. This allows the mortar to "slake," allowing the latex additives to fully activate.

Tips and warnings

  • Always wear latex gloves. Portland cement is the main ingredient in thin set mortar and can irritate the skin.
  • Consider mixing small batches. Most manufacturers recommend that you mix only as much mortar as you can use within about 20 minutes. Most thin set mortars become too thick and unworkable after that time.
  • Never overmix. This adds air and heat to the thin set, compromising its durability as well as shortening its usability time.

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