Violin Forum/Message Board

[jethro]

Tested some sodium silicate as a ground. Took some maple side scrap and put om a yellow water based dye. sanded. Painted on sodium silicate
solution (full strength) and let dry over nite. Sanded slick (very) and added a coat of varnish. Also tried varnishind a spot where there was
no sodium silicate. The sodium silicate seemed to raise the contrast
and darken the flames in the side material. It darkened a little to a shade
maybe golden - brown and made the flames darken and stand out a little
more. Both with and without seemed to have dichroism. However it
allmost seemed like the spot without silicate (only yellow dye) might have
a little more "glow" to the look of it. Hard to tell with onlt a single coat
of varnish.
Any experience with silicate ????????
Tim

[Jack H.]

I hate using the stuff.
perhaps it is my technique, but I never was able to achieve good results with it.
bad adhesion of varnish over the silicate and other issues will prevent me from using it again.

a nice shelack ground works just fine.


good luck!
J

[Michael Darnton]

I don't like the stuff, never found a good way to use it, and it's destructive of the wood. That said, it sounds like you're using it too concentrated. It should go on as a wash that doesn't leave any residue or coating on the top of the wood, only inside. I don't remember the dilution, but you need to mix in quite a bit of water--I seem to remember something like 1:10 or 1:7, silicate to water--something on that order.

[jethro]

Thanks Jack and Michael :
I used it full strength out of the jar- about like crunchy molasses. I let it
set for about 5- 10 min than I wiped off excess. Today I tried full
strength again but DID NOT wipe the surface-- it hardened into a thick,
hard crust that was fairly hard to sand down with 150 grit paper. Also
tried a diluted coat about 1-10 or 1-20. Didn't see much visual change
for the diluted version.
OK, my gut feeling is that it is not overly loved ! If there are "issues"
of it not playing well with varnish above it that's enough to make me
avoid it for now.

I think I will go with a shellack ground.
When I make shellack sometimes when I spray the solution i can see
TINY freckles in the coat. Either shellack or more likely I suspect
undisolved Transtint which I have colored it with. I usualy put the
Trans tint in about 5-10 ml of acetone- mix- and then dump that
into the shellack solution. I am using Hock brand wate free alcahol.
It appeared that normal hardware store methanol didn't quite dissolve
the shellack flakes. I figured it may have a small % of water in it, so
I went with hock- which claims to be just for dissolving shellack.

Any helpfull tips for shellack ground? Or does my formula sound OK
(and I strain the solution before I spray it !!!!!!! usualy lumps)

Thanks Tim.

[Michael Darnton]

The only shellac I have successfully sprayed was in a can from the hardware store. When I use my airbrush, it's not clear enough--I suspect the difference is in the solvents. I would brush it, and I would dilute it quite a bit, like with the silicate, so that it soaks in deeply. I usually use three or four coats, and don't see any buildup in that time, though the wood is well sealed.

[jethro]

Thanks Michael:
I will get a good quality brush and try carefully applying with a brush.
This time I have taken my shellack flakes and put them in solution and than warmed the solution for about 8 hours (160 f) stirring every hour
or so. Since the solubility seems rather low I may keep up this routine
for several days to ensure a better solution. When I first put in the alcahol
after about 2 hours I had a partial gellatin so I added more alcahol which
seemed to un-supersaturate it. It looked a lot better after that- though
still really concentrated. Will probably dilute a lot more tonight !
I'm probably getting the alcahol so saturated that when I add trans-tint
it won't go into solution and makes little micro balls which spray out as
little color freckles. they appear to ba about .010-.020 inches.
I have noticed the transtint won't even dissolve easily in pure alcahol.
So It's solubility does not appear to be great to start with.

Thanks for the brushing hint- I will see how it worls !

Tim

[mikemolnar]

Rubio used a 50% water-potassium silicate solution.

http://www.rubioviolins.com/

On the subject of shellac, I too love the stuff. However, I was almost scolded by a top maker for using it. Go figure.

[Jack H.]