Use of tree resin in finishes

[tonyw]

Violin makers of times gone by had various formulas for their varnish. Some used resin (or gum - is that the same thing?) dissolved in linseed oil or something else.

I was thinking of trying some spotted gum resin dissolved in linseed oil. Is this a silly idea? Has someone tried something like this?

Spotted gum resin looks to be a nice red colour and there is plenty of it around here.

[Big Shed]

Don't know about the resin(gum) from spotted gum.

You might want to Google on rosin, Wikipedia (http://en.wikipedia.org/wiki/Rosin) is a good start on the subject.

[contrebasse]

I've managed to get a nice result with using dark red stringybark kino dissolved in meths. Used on its own, its rather brittle. But mixed with shellac, it gives a much nicer and more durable finish..

I've dissolving tried other gums in gum turpentine with varied results. Sometimes the gum doesn't want to dissolve. Other times it does, but slowly.

I've not been very scientific about it cos i only get kino every now and then, I'm a city slicker. But if you have easy access to tree gums, get out those peanut butter jars and
keep some records of what species dissolves in what. Could be useful!

[bystander]

I have not used it myself but have a friend who uses the resin from dead grass tree's. Have seen the results and it looks good, but only ever seen it used on dark timber thus it appeared dark. Can help you wth some if interested, but depends where you live in Brisbane.

Regards

[tonyw]

Thanks for the offer. I live in Brookfield but at the moment I am engaged in another project and would not have time to experiment.

I found some varnish recipes on the net. One of them uses resin dissolved by heating in linseed oil and then adds turpentine, but warns against doing this inside.

[Andy Mac]

I tried dissolving gum from acacia trees, not sure of the species, but very common regrowth here on the Darling Downs. Nearly every tree has gum deposits, some quite fresh while others are glassy hard, so it wasn't difficult to collect a tin full. The hard bit was dissolving it...tried nearly every solvent I could find, even went into the Biol lab here at uni. I ground it up and still couldn't get a useable product, but maybe I was too impatient.
I think copal is an acacia product, from Africa and the Middle East, used for varnish, so it must be feasible.

Good luck,