The Rot Doctor


Subject: CPES reactive with mortar residue
Date: September 8, 2012

We have a 200 yr old house. We removed the plaster ceiling on the 2nd floor to expose the joists and give more head room. Whoever plastered the ceiling ( a very long time ago ) dealt with already existing rot by filling cavities in the joists with mortar. The size of the cavities ranges from the volume of a golf ball to the volume of a quart. I have removed the mortar, but there is no doubt some lime/calcium residue in the cavities. Some hardeners caution against using their product due to chemical incompatibility/reactivity with alkalies/lime/calcium. Is this an issue with CPES? What kind of reaction are they warning about?


There is no issue with CPES and lime or plaster. I have personally used the CPES on plaster and mortar lots of times. Lime is a fairly strong chemical, so it is apt to cause a chemical reaction, or interfere with certain chemical reactions. Just not with our epoxies. Or epoxies in general.