Old School Pumice “Sanding” Block
A few days ago blog reader (and the Lou Gehrig of the woodworking blogosphere) RalphB asked about my use of the pumice block to smooth the surface of my parquetry Kindle case. The use of pumice blocks is well documented in historical accounts, although explicit or specific details are often missing.
I use a pumice block from the plumbing section of the hardware store (I order them by the case). Normally they are used for deep cleaning of porcelain and enameled fixtures to remove mineral deposits and stains. They work equally well for evening out irregular wood surfaces such as those found when assembling parquetry or marquetry from sawn veneers, where regardless of the care in the initial veneer sawing a fair bit of irregularity is manifest.
I generally use a pumice block as the step following the toothing plane/Shinto rasp, moving the block in a circular fashion on the substrate, yielding a fairly smooth and even surface about what you might expect with 60 or 80 grit sandpaper. Following the pumice block with a card scraper and polissoir, the result is quite pleasing.
Glad I asked. I thought it was a block of wood and pumice dust. I have some pumice blocks like you said.