A fast way to to pore fill blackwood

[Robdon]

Hello,

I have just finished my first build (I posted a photo in an earlier post). The back and sides are figured Tasmanian blackwood which looks beautiful but has a lot of pores and I want to french polish it. I started off with a traditional method of rubbing pumice into a scratch coat of shellac with an alcohol wetted muneca described on the “guitarsint” website. It was very slow and I wore out a few munecas without much impact on the pores. So I decided to look at something a little more abrasive and this is the method I devised: it only takes 15 or 20 minutes or so to rub a guitar back
Apply three scratch coats of a 2lb cut of shellac. It doesn’t have to be neat because most will be removed so just wipe it on with a cloth dipped in shellac with an hour between coats.
After it is dry (I left it overnight) sprinkle a very light dusting of pumice on the area to be treated (about 1/4 of the back at a time). The dusting should be so fine that you can feel it but not see it.
Drop some alcohol on the pumice. I put enough drops to wet about half of the area after they spread out on the surface.
Wet all of the pumice by rubbing with your fingers
Put a couple of drops of alcohol on a piece of 600 or 800 grit wet and dry sandpaper and rub very gently in a small circular motion. The only pressure on the sandpaper should be the weight of a couple of fingers.
From time to time add a few drops of alcohol to the sandpaper and keep rubbing until most of the shellac is rubbed off.
It takes a bit of practice to get the right amount of alcohol. I found that when very small balls of shellac/sawdust/pumice were formed was about best.
I filled most of the pores with one application but repeated the whole process just to get it perfect.

I thought that what I was doing was mixing sawdust made by the sandpaper with shellac softened by the alcohol to fill the pores but if I left out the pumice it didn’t work as well so maybe it does something more than just being an abrasive.

Best wishes,
Rob