How to Seal Mortar Around a Glass Block Window

How to Seal Mortar Around a Glass Block Window
Written By
C.L. Rease
C.L. Rease
Published: Oct 27, 2011
Updated: Nov 20, 2021
2 minute read

Proper application is necessary to ensure the glass block structure remains stain-free. Even a small gap in the sealant will allow fluids to seep into the mortar, defeating the barrier provided by the mortar sealant.

Things You Will Need

  • Liquid mortar sealant
  • Spray bottle
  • Lint-free rags
  1. Pour liquid mortar sealant slowly in a spray bottle. Do not allow air bubbles or foam to accumulate inside the sealant.

  2. Move to the highest horizontal mortar line of the glass block window. Hold the tip of the spray bottle nozzle 1/2 inch away from the mortar joint. Spray sealant on the joint as you slowly move the bottle along the seam. Spray the remaining horizontal seams. Spray a light coat of sealant on all vertical mortar seams.

  3. Rub the sealant into the mortar joints using a lint-free rag. Wipe the surface thoroughly until all excess sealant has been removed from the surface of the glass blocks. Allow the sealant to dry for 45 to 60 minutes.

  4. Buff sealant residue from the glass blocks, by wiping across them with a clean lint-free rag. Move the rag in a circular motion if the hazy residue is difficult to remove.

The Drip Cap

  • Stains and mold are common on the porous mortar that holds glass blocks in place.
  • Do not allow air bubbles or foam to accumulate inside the sealant.
  • Spray sealant on the joint as you slowly move the bottle along the seam.
  • Rub the sealant into the mortar joints using a lint-free rag.

Photo Credits

Jack Hollingsworth/Photodisc/Getty Images

Jack Hollingsworth/Photodisc/Getty Images

C.L. Rease

C.L. Rease , based in Texas, has been a professional construction and outdoor writer since 2003. His articles have appeared in The News-Press, a local Southwest Florida newspaper and a small Southwest Florida fishing magazine. Rease served…

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