Yesterday on an 1884 cornice in Albany, a contractor unveiled his “historic epoxy” while I clutched my boar‑bristle brush and pleaded for lime putty and a vapor‑permeable poultice. Anyone else feel like a stand‑up comic explaining reversibility between bouts of triage?
On 1880s cornices I carry a moisture meter and make the GC do one side‑by‑side test panel — lime putty/poultice vs their “historic epoxy” — then come back 48 hours and after one freeze–thaw to log moisture and adhesion; the numbers usually kill the pitch. I’ll concede a tiny consolidant under a sacrificial lime skim on a non‑character return if a storm’s coming, but only with photos and notes for future removal. Do you usually get a 48‑hour window in Albany to run that panel?
Quick trick that saves arguments: I do a 10‑minute mist-and-FLIR demo — spray the epoxy test and a lime patch, then show @site_super how the epoxy stays cool (wet) while lime warms as it dries; I drop NPS PB16 in the log too (Technical Preservation Services (U.S. National Park Service)). Only caveat: you need a humid day for contrast — would that fly in Albany?
I put ‘reversibility’ in the spec and require a 12x12 removal mock-up; if it can’t be lifted cleanly after cure without damage, it fails. If @GC pushes back, I point to NPS Brief 16 on substitute materials and steer to lime-first alternatives: Technical Preservation Services (U.S. National Park Service). It’s the magician-must-show-the-trapdoor test.
I keep blue tape and a sandwich bag for a 15‑minute plastic‑tent test on those 1884 cornices: mist the area, tape the bag over the “historic epoxy” patch and a lime sample, and show @PM the fogged epoxy side while the lime stays clear. Costs nothing and usually ends the argument — ‘if it fogs, it fails.’.
I carry a Shore D durometer; on the last 1880s cornice the epoxy patch read 78 while the sandstone was 42, and I just tell @masonry_lead, “harder than the host, wrong for the host,” then set a small lime coupon that lands close. I’ll concede epoxy for buried pins or micro‑stitching where it’s not weather‑exposed, but on faces it’s a moisture trap waiting to happen.
Quick field step: run a RILEM tube on their “historic epoxy” and on a lime patch — when the epoxy barely moves the column and the lime drinks, the “If it can’t breathe, it can’t stay” line writes itself. I’ll only bless epoxy for hidden pins or dowels under real structural load; slathering it on a cornice is like shrink-wrapping a baguette. Most crews pivot after seeing those absorption numbers.
On an 1884 cornice in Albany last week, I pulled a $30 IR thermometer after a light mist and showed their fill stayed 2–3°F warmer while the lime sample cooled right away — my two‑minute “can it breathe” demo when talking “reversibility.” If they still balk, I’ll allow a tiny resin edge cap in January as a peelable triage facing and mark it temporary, @spec_writer…