Re-re-hola. That goes for "materies que serveixen per calafatar", would you believe it... "Slag wool(insulator)" for aïllar. Not sure for "tancar amb estopa" although it could've sthg to do with "steel (or mineral) wool insulation", 'fraid dunno enough about these patent matters. Check it out, there heaps of insulators in the page below and, remember, if they specify so much in the original, it must be for a good reason. Piperpat's cool, ain't it? Cheers :-)