Internal Varnish?

Rob MacKillop

I've read that all the Selmer guitars were varnished internally. What are our collective thoughts on this? Does it help push the sound out? Or does it hamper a more acoustic voice? Castelluccia offers it as an option, but I'm not sure which way to go.

Buco

Been wondering the same for a while. I've heard modern luthiers who do it to build a period correct instrument but never heard much about any acoustic benefits it might have. Or was it just a way to further fancify a higher end instrument?

bopster

I've played 2 JP Favino guitars that have a full, dark sound, and neither has internal laquer. According to the owner of these guitars, Favino feels the laquer on the outside of the guitar needs to be thin, compared with other luthiers, and he has his own "formula" he uses.

Most of the guitars I have played have not had the internal laquer, and the sounds have run the gamut, from bright to dark.

Craig Bumgarner

My take is the interior finish helps moderate humidity changes and keeps the interior clean, less dust collection and chance of mildew. To be effective, the underside of the top needs to be sealed as well. To me it also looks nice, a nice touch and I always finish the inside of the body, top included. I use a couple coats of shellac which is very thin, quick, easy and a decent moisture barrier. I like to think my guitars are more seasonally stable because of it.

I don't think an interior finish has much affect on sound unless it were carried to extremes. Roger on thin coatings though I think this gets over emphasized sometimes. A thin finish inside or out is not in-of-itself a silver bullet to good sound. There are hundreds of such things that go into making a guitar sound this way or that, and these are only the elements we know about, there are probably lots more.

Rob MacKillop

I get your points, though I've never once had a guitar get mildew, including one I possess from 1765! But I guess it does happen to some.

Craig Bumgarner

Oh yeah, it does happen. Many of the French guitars from the 40s and 50s I've looked at have some mildew inside, one or two were scary bad

Buco

But if, as Craig suggested, may be helping with staying stable during seasonal changes then it would be important enough for me to consider getting it on a guitar.

Jazzaferri

Rather than varnish, a coat or two of Shellac gives the best moisture resistance for the least thickness. Bob Benedetto shellacs the inside of his guitars if I recall the video correctly.

Rob MacKillop

Thanks for the info.

Al Watsky

You see mildew and mold living on dust balls and in one memorable case carpet mites !
They were eating the label on a Contreres guitar and feasting on the glue and dust.You could actually see them walking around in there. Fun ! Snuffed them with naphtha !
As Craig was saying the internal finish makes the guitars more stable , more resistant to humidity changes.
There is a slight difference in sound but its not perceptible to any large degree. You might get a similar sound difference by finish sanding the interior and braces and glue sizing .
The interior finish is a nice touch.
They don't call it finish for nothing.

Rob MacKillop

Thanks, Al. Sounds horrible!