Hi. I have a masonry heater. The pizza oven door has always leaked some smoke. What is the white hand woven gasket material? And can you suggest where I can buy either (1) raw material that i could just pack in, or (2) finished pre-woven gasketing? It is glass wool or rock wool? Best to DIY add a bit in w some 'glue' or replace with a thicker-heftier woven pre-made? Thanks much - Mike