Removing old shellac?

[blackalex1952]

In a recent post one of the members said that they had applied some tinted shellac to a soundboard, then decided that it looked bad and removed the shellac. I have been working on a guitar and have done exactly the same thing, deciding to remove the shellac. However, I have found that it clogs sandpaper, and any vigorous sanding causes the shellac to form hard resinous spots which I have had to remove with a scraper! Any resinous spots on the sandpaper ding the delicate spruce as well. So lots of cleaning the sandpapeer with a wire brush. A palm sander is definitetly a recipe for disaster for this reason. There must be a better method for this process? Cheers! Ross

[Fisherman]

Remove as much as you can with 100% alcohol first...

[kiwigeo]

I've done this more times than I care to remember. You can go in with alcohol and then finish off with sandpaper. Sometimes I start with a cabinet scraper before finishing off with the sandpaper. Other times I've gone with sandpaper all the way from start to finish.

The great thing about shellac is that it's not that hard to go back to square one if things start going haywire with the finish.

[peter.coombe]

Yep, also done more times than I care to remember. Sometimes use a scraper, or alcohol, but usually sandpaper and lots ends up in the bin. Lots of sandpaper, lots of elbow grease, and lots of patience, but always I am happy I got it off and start all over again. Second attempt is always much better.

[Trevor Gore]

How old is old?

Old, fully hardened hard shellac is pretty well impervious to anything, including methyl chloride based strippers. Sanding works best on that stuff.

Recently applied shellac will mostly wash off with IMS, even if you used hard shellac. I've had cases where I've tried to FP WRC and on some wood it just won't happen, I think due to oils/resin in the wood, which isn't removed even after two or three attempts followed by IMS wash-offs. Those get sprayed with nitro! Most WRC FPs fine though. Go figure!

[blackalex1952]

Thanks for the replies, gentlemen. Yes, that's exactly what I did...alcohol wash, elbow grease, scraper and patience. Was hoping for a trade secret here. Damn! Work!
The soundboard is Italian Alpine Spruce, nice white colour. What was I thinking ? Putting shellac on it in the first place? Looks pretty stunning now, Claro b&s and neck. I have tinted the nitro on the body and neck and put a subtle burst so that the fiddleback areas stand out a little more. The walnut tint in the finish, with a touch of amber (red and yellow) has both darkened and warmed the Claro up quite a bit which is a nice contrast with the creamy Top. Silky Oak bindings, L-OO body, pyramid bridge, lighter but similar bracing to the Gibson X, with four finger braces and a closure and forward shifting of the X braces. ( the plans I have show the taller thinner Gibson brace profile and two finger braces ) Thirteen fret neck join, which I believe places the bridge in a nice part of the soundboard, considering the forward shifting and closure of the X. I expect a bright sounding guitar suitable for most lead styles with strong mids and good bass support. Oh, and a short scale-which I took into consideration when I chose the 13 fret body join and placed the bridge, thinking a bit about where the ends of the bridge would couple with the X. It's going to a muso who is not a strong guitar player, but who works with lots of visiting musicians who will most likely be playing it, so it will be passed around the visitors and family members who also play. Yes, she's gonna be anybodies! Can't wait to hear it strung up. The extra width of the L-OO lower bout and the body shape of this design really appeals to me, the first one of a few I hope. Cheers! Ross

[Dave M]

Pics Ross...?

[blackalex1952]

I thought I might get that question re pics...so many amazing builders on this site and some fantastic builds, makes me feel a little shy, but here goes in the interests of the aforementioned Walnut binding colour scheme...this guitar will be strung up and the bracing fine tuned soon, so looking forward to that process the most, ie hearing what I've done this time, and also a new body shape build for me, along with my own variation on the bracing...Pix taken on a rotten old iphone 4 which is on its last legs. Cheers! Ross

[blackalex1952]

A couple more...pyramid bridge. The soundboard is lightly braced, but with the taller thinner Gibson L-OO brace profile.
25 ft soundboard arching 15 ft back arch- I closed the X a little then forward shifted that, as well as adding extra finger braces, slightly re arranging the tone bars to stabilise the lower bout after the braces had been moved; all designed around a short scale 13 fret body join. Closed without the brace tuning and no bridge, I have also put my initial Visual Analyser shots. I expect the bridge mass to drop the top to around 185-190. A little concerned re the already low Ti 1,1 resonance dropping off the radar as dropping the soundboard resonance usually pushes that one down due to the frequencies repelling each other.