Removing polyurethane foam from brick

We have a part of a medieval brick wall that had been block-lifted
using polyurethane foam about 30 years ago. Unfortunately, no
separation layer had been applied to the object prior to foaming. So
the foam adheres quite well to the brick and mortar. Now it needs to
be taken off the foam and cleaned for an exhibition. I have tried
dimethylformamide, and paint stripper which swells the PU-foam which
then can be scraped off mechanically. These methods are rather
tedious for an object of almost one square metre surface. We wanted
to try dry-ice blasting which is however meant to be rather damaging
to the brick surface. Does anyone have any other idea for cleaning
off the PU-foam?

Petra Nirmaier
Kanton Luzern
Dienststelle Hochschulbildung und Kultur
Denkmalpflege und Archaologie
Libellenrain 15
CH-6002 Luzern


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                  Conservation DistList Instance 26:47
                  Distributed: Tuesday, April 30, 2013
                       Message Id: cdl-26-47-019
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