How to Clean Efflorescence on Terra cotta Wall Panels

David from Wisconsin called to discuss a solution to Efflorescence on Exterior Terra cotta wall panels installed on a commercial building.

After discussing the matter for several minutes, here are the particulars:

  • Large size terra cotta units installed on a commercial building using a mechanical Z-clip fastener.
  • No setting mortar used to adhere panels (eliminates one source of problem)
  • No direct contact with substrate directly behind panels. Small air space behind also eliminates a potential cause of problem.
  • No mortar or grout joints used in mechanical anchoring. Another potential source of problem eliminated.


Atmospheric and or exposure to rain on the surface of Terra cotta is reacting with salts inherent in clay type products.



Clean panels using HMK R55 Intensive Cleaner and to reduce future efflorescence problems, Seal Terra cotta panels with HMK S31 Silane Impregnator. This will help prevent moisture from penetrating the surface of the panels which will reduce the chemical reaction of salt crystals growing and migrating to the surface.

About Torin Dixon

StoneCareOnline Expert Blog is managed by Torin Dixon who is an expert in natural stone importing, distribution, fabrication, installation and maintenance of all natural stone surfaces regardless of finish or texture. We are here to assist you in your StoneCare needs.
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