Help: Ill- and/or over-varnished soundboard

Dear all,

I am making a harpsichord right now and I consider myself a clumsy hobbyist. Yesterday I tried to varnish the soundboard but, maybe it’s not well prepared, or more likely maybe the solvent-based varnish that I chose is too thick — the varnish is applied not at all evenly with dried smears and ripples from place to place. (What I initially hoped is but a thin and even one.) Now the soundboard looks pretty ugly and I truly wish to do something to redeem it. What should I do? I would be very thankful if you could give me any advice.

Many Thanks

Can you strip it off? AFAIK, soundboards are never varnished. A light shellac would be ok if you don’t want bare wood…

How it has been mentioned, by all means strip the varnish away, maybe with a card scraper or with a solvent. When you arrive down to bare wood you can treat the soundboard with:
A) the white of two or three eggs (beat them as you would when preparing an omelette);


B) shellac dissolved in alcohol, not too thick;


C) glue size. Prepare hide glue in water in the ratio of 1:15 or 1:20 (1 spoon of glue to 15 or 20 spoons of water). Brush both the sides (interior and exterior). Don’t be horrified when you’ll see the soundboard warp horribly. In a few hours it will dry again and return as it was before brushing the glue.

My preferred is C, as I found it both is effective in preserving the soundboard from dirt AND enhance greatly sound transmission. The sound trasmissione enhancement is apparent if only you caress the soundboard with your fingers.

I have tried the shellac as well, with good results. Never tried the egg-white, which however is advocated by some experienced makers.


I have never removed varnish from anything as delicate as a soundboard. You will need to work with great care, regardless of the method you use. Perhaps someone who has done this can give you better directions.

If you are able to remove the varnish so that the board looks acceptable, keep in mind that there is almost certainly some remaining in the pores. This will probably affect any treatment that you put on top of it (In other words, the shellac might not sink in evenly). So you might be better off leaving it bare.

If you buy shellac at a hardware store, it will need to be thinned considerably, by a factor of three or four.

Good luck!

More information might help. For example:
Is this a harpsichord kit? If so, what kind?
Are you building from a plan or book, or designing your own?
What is the soundboard wood?
What kind of varnish?
What is the state of construction?
How long ago did you apply the varnish?

Welcome @ⵘⵘⵘ to the forum.

As @EdS says, giving more background would be helpful. There are very few historical harpsichords that had varnished soundboards for the simple reason that it kills the tone in a harpsichord (unlike violins where the varnish is hugely important). This is the reason that very light sealants such as egg white or thin glue size were used, or indeed, nothing.

If the soundboard is spruce, it’s not delicate at all, in fact, it’s a very tough wood. I’d have no hesitation using paint stripper to pull off the varnish, or using a scraper. I suppose you have varnished over the bridges too - that really needs to come off, at least on the top - you don’t want varnish rubbing off onto the string, which it would.

Of more concern is where you got the idea to varnish to begin with. What led you to that idea?

There are not many builders on this small list, but you are most welcome to ask about any aspect of building, and there is no such thing as a stupid question.

@ⵘⵘⵘ may I also refer you to this page by one of our members?

Thanks for the heads-up regarding thinned hide glue (Titebond for me) as sealant for sound board. It is reversible as well.
I will follow this advice on my model of a late 17th C. German clavichord: C/E to c3, 28 courses. I doubt it will ever play, but I am fascinated by all early keyboards and the literature (built Zuckerman Straightside Hrpschrd 55 years ago–home-crafted case). I call him “Rigoletto” in his court jester costume/decor.
My current clavichord replica is from a down-loaded baseboard plan crafted from scrap wood (Keith Hill’s “Bauerninstrument”). I refer to it as my “Scrapsichord.” My goal was for it to look like an ancient attic find.

Thanks to all who contribute and who manage this site. I am a great admirer of you who can expertly build and actually play these instruments. I am a wannabe…

We use egg white. Egg white was also used as the basis for tempera for soundboard paintings. I am compelled to say I use organic free range chicken eggs!

@domenico.statuto I don’t see the need to beat them. My understanding is that what that does is introduce air, which you need for making meringue etc. I can’t imagine it makes the white easier to apply, but I am sure the bubbles would just disappear.

This may be a misunderstanding on my own. As I said, I’ve never used egg white, only shellac and glue size.
I imagined the un-beated white would be difficult to spread evenly as it is colloidal, somewhat sticky, while it becomes more “liquid” when beated. Of course I stand corrected and I urge the original poster to follow your indications which have proven successfull for many years: unbeated egg white.

Dear Andrew:

I have never used beaten egg white as a finish, but an organ builder I know uses it regularly. He explained you must beat the white until it is stiff. Let it stand and then the liquid which gathers at the bottom is used to brush on. If you have otherwise had experience with egg white, if the egg is fresh the white is usually somewhat coagulated.



Not with our Aussie chooks! :slight_smile:

Actually coagulated is not the correct term. The egg white does though stick together.


FWIW, in 1980 I built a Zuckermann Flemish IX and meticulously followed the inspired instruction manual. (I recall David Way suggested thinned shellac with solids settled out.) Later, an acquaintance built the very same kit, but couldn’t bring himself to RTFM and decided to apply all his knowlege of wood boat building - using a thick layer of acrylic boat varnish instead. The difference in sound was dramatically depressing.

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The late English makers Shudi and Kirckman always varnished their soundboards and it certainly did not kill the sound - these instruments are known for their magnificent, rich and brilliant tone. We don’t know what they used exactly but it probably had some sandarac in it and was probably spirit based. Hardly any oil, or perhaps none. I haven’t been able to compare a varnished to an unvarnished strung soundboard for obvious reasons, but judging by tapping (very subjective obviously) the varnish considerably improved the response after a couple of days. The recipe I used (following Chris Nobbs’ advice) was 3 to 1 sandarac to mastic in alcohol with a little elemi and a few drops of oil of spike. Although it dries quickly it seems to take a 2 or 3 days to
harden. The soundboard was sized with thin glue first and I think this was very commonly done - both sides. I have had good results this way. Thin glue makes a good grain filler too. Obviously it should be proper glue - using titebond as a size sounds like a very bad idea.
I think I know the 1775 Kirckman double mentioned by Tilman. If it is the same one, it had a lot of mildew on the soundboard as well as some sort of degraded finish and some remnants of the original finish when it went to my colleague for restoration and he had considerable trouble removing all that. Of course I don’t know what its history might have been since Tilman worked on it - if it is the same harpsichord. Once the soundboard was repaired it was refinished with the varnish described above and the tone is wonderful - I have seen and heard it.

Only the English makers seem to have done this but that doesn’t make it eccentric or illegitimate - just a different practice. One doesn’t usually see English soundboards with mildew on them.
Huw Saunders

He did say Titebond Hide Glue I believe.

So @Huwsaunders that does sound like what violin makers and others refer to as spirit varnish. Most interesting.

This is essentially the White Hard Varnish, used throughout the nineteenth century to finish light-coloured woods and, at least in the British piano trade, continuing well into the twentieth century.
See, for example, John Phin, Practical Hints for Furniture Men (London, 1880), where gradations of the proportion of Venice Turpentine to be used are prescribed, according to whether the finish is to be polished or not: more if polished, less if not.

Right, a lot could be said about that process that wasn’t apparent to me when I wrote the blog post that Andrew linked to. The “degraded finish” would likely be what remained of the quite unspeakably thick layer of shellac that had to be removed; the latter I do actually remember quite clearly. Remnants of the original finish were not observed by the head of operations (Martin Skowroneck, my father) at the time (1978), it’s as simple as that.
I would believe that my father either did not know that the original English instruments were “always” varnished, or maybe he disagreed. In the early 70s he had restored the 1778 Shudi and Broadwood in the Norsk Folkemuseum. I vaguely remember that that soundboard was in a good condition, hence left entirely alone, and was not varnished; it’s a late instrument and perhaps there was a change in the production around that point; the soundboard of my 1805 Broadwood grand piano is not varnished. Perhaps he drew the wrong conclusion from that instrument. Whatever the case, I can’t ask him any more.

“The history” is that the instrument stood in the Bremen workshop for all those years, first playable, later less playable, and eventually entirely untouched; the mildew built-up was the result of time passing and neglected dust removal, about which I was quite amazingly grumpy when I found out.

Water under the bridge, but fair point about the original varnish on English harpsichords.