Official Luthiers Forum!

All they had at my local hardware store was white shellac. Can anyone tell me if it's useable
a) on raw spruce
b) on epoxy porefiller
I plan to spray KTM-SV on top. Any help would be appreciated, the net in general is too full of conflicting info, much of which isn't even applicable to instrument making

I would use Zinsser Bullseye shellac sealcoat for what you intend. The white shellac you state may have wax in it or it may not. You didn't give a brand name or state that. You want a dewaxed shellac for a sealer. The bullseye will work under the KTM-SV.

I would also go with the Zinnser product. I have used it successfully under another water based laquer, both on the raw spruce and above the oil based filler before the top coats.
Good luck.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Thanks folks,
The stuff I have is basically no-name brand. It doesn't mention being de-waxed, only that it is a "2 lb shellac". Whatever that means. Oh well, on the hunt for zinsser...

Hmmm,
Closer inspection of the bottle revealed a small recochem logo. Apparently the company states that it has no wax additives. I'm not sure if that's the same as being de-waxed.

I read about Zinsser Sanding Sealer shellack on Frank Ford's website:
http://frets.com/FRETSPages/Luthier/Pro ... nsser.html

He said it was also good for french polishing, so I bought some and tried it. Worked as good as my own fresh mixed shellack from flakes. And it has a two year shelf life.

I use it for french polishing banjo peg heads, as a sanding sealer, and as the first coat over cocobolo, granadillo, and the other oily rosewood family woods. I use TRu-Oil a lot on both guitars and banjos. Tru-Oil right over my cocobolo banjo tone rings stays sticky for a long time. If I first do a couple of coats of shellack, the Tru-Oil dries in a couple of hours.

Here's one of my cocobolo and maple block rims. Sorry to put banjo stuff in the middle of all the great guitar stuff, but banjo stuff pays my bills and allows me to feed my hobby of guitar building:

Wax is naturally found in shellac so being that they state there is no wax additives is not the same as being dewaxed....mike

Nice banjo rim. I wish there was more banjo and mandolin stuff on here. I wish they would create a section for other instruments like they did for the resonator section....Mike

I usually test things like shellac and epoxy, etc by putting a few (large) drops on a piece of glass or similar.
If the shellac 'dries' clear, nice and hard and sands well (powder) I figure it's OK to use. If the result is soft/gummy, I reject it.
That said, I generally use shellac flakes and mix up my own, but I still like to test stuff 'on the shelf' to see if it is usable, even on non-guitar projects.
Cheers
John

That's what I needed to know. Best to err on the side of caution. Off to find Zinsser...