[pianotech] permanent marker

[Ron Nossaman]

On 8/25/2012 8:57 AM, Ron Nossaman wrote:
> It's probably much more efficient in
> time and money wasted to just Google some up and UPS it to your front
> porch.

Hey, I forgot the most important use I have for pumice. with the key top 
thing being a distant second.

To whom it may concern.

I finish soundboards with pre-cat nitrocellulose lacquer. I don't use a 
filler, and I don't use sanding sealer or varnish because I don't want a 
soft heavy finish on my boards. So after spraying the first coat of 
lacquer on the bare spruce, I'm looking at sanding lacquer prior to 
applying subsequent coats. Dry sanding lacquer, as anyone who has tried 
it (especially with fresh lacquer) will tell you, doesn't work. The 
sandpaper clogs up immediately. Since I have no desire or intention of 
flooding my board with a liquid lubricant, I needed an abrasive that 
doesn't clog up. I found that 150 grit paper on my pad sander, with the 
soundboard surface sprinkled with that FFF pumice, worked wonderfully. 
The grit of the paper both does some of the cutting, acts as a matrix to 
hold the pumice as it scrubs the lacquer, and the pumice keeps the paper 
from goobering into uselessness. I can watch the light reflection off 
the surface with each sweep as the high spots, dust, and spruce surface 
fur lose their gloss and merge into a satin sheen that is an ideal 
surface for the next coat of lacquer. I typically sand two coats, and 
topcoat a third, leaving a finish that isn't mirror flat and raccoon 
shiny, but is light, tough, and adequately sealed by my criteria. 
Exactly what I want, and used 1/4 sheet of sandpaper and a couple of 
tablespoons of pumice for the entire job.

There's no reason I'm aware of that this wouldn't work in any instance, 
like case touch up, where a finish or patch needs to be leveled, and the 
likelihood of breakthrough and contaminating the underlying wood with 
your lubricant is high (as it is with the soundboard on the first coat). 
Breaking through with pumice leaves no contamination.

Try it. You might find it useful for things I haven't thought of, which 
you can then tell the rest of us about.

Ron N