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Jack Devereux

Opaque Linseed Oil

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Hey folks- I'm just beginning to dip my toes into varnish making, and had a question about washing linseed oil. I bought a jug of Kremer's cold pressed stuff and put it in a big mason jar with some water as outlined in Mr Hargrave's bass article. The oil, which was a kind of golden/yellow and translucent in its own bottle now looks like orange juice and is totally opaque. Is this normal? I haven't siphoned off the first batch of water yet, and there's definitely some crud settling out. I got paranoid and thought maybe I had left a little dish soap residue in the jar when I washed it out, and that might have done something to the oil? Or it may just be that I need to run a couple more batches of water through it and let it clarify. Any thoughts are greatly appreciated!

Thanks,

Jack

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Yep this is pretty standard. Syphon off the orange stuff at the top into a clean bottle (I use a turkey baster) then leave the clean stuff in the sun for a couple of weeks. OR you could simply go to the art supply store and buy some refined linseed oil from Gamblin. Refined linseed oil is what's used in Gary Bease's Strad article on varnish making.

 

Roger, by the way doesn't promote the use of sand and salt noted in Tad Spurgeon's article noted above, Roger just uses water. 

 

The one thing not noted in the Bass book on the resin side is that you will need to cook your colophony up to 80 loss at around 125 to 150 degree C to get the kind of colour Roger does. Not an easy thing to do!

 

One of these days I'd like to do an addendum to the Bass book that summarizes some of these little details that got left out. 

 

Cheers

 

Chris

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Thanks for the info! This is just water, no sand. I've read about that but figured I'd try the simpler method first. Is that any more effective or faster? Will the Hargrave recipe work with art store refined oil?

I bought colophony and mastic per the Hargrave recipe. I knew it was a fairly long cooking time, but good to have the temperature and a rough idea of how long it will take. I had been planning on calling Joe Thrift and picking his brain about it, his varnish is very similar to Roger's.

Anyway, just glad I didn't screw up forty bucks worth of oil.

Thanks!

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Jack

 

For the moment it's ok.
Follow Roger instruction and you surely you will arrive to good results as I did.
I washed several times and siphoned the water repeating the wash.
When I considered enough wash I settle in the window the jar and the oil clarified nicely.
I cooked the colophony about 100 hours. Beginning at 130 cº first and increasing at the point it made bubbles and not far from 180cº.
 
The varnish resulted very good but I would like more dark.
 
Regards
Tango

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Jack, it sounds like you bought Kremer's raw oil, so this means the temperature at which you cook just doesn't keep the rosin melted to react with air but also affecting the bonds in the oil converting them to gel and form a film. As you increase the temperature the rate at which the bonds in the oil change to drying oil type also increases. For example, at the temperature at which rosin melts, the reorganizing of the oil bonds to a true drying oil I'm guessing would take weeks, but at say 400oF it would take maybe a 12 hour cook. This is just to give you an idea of what is happening when you a cooking the mixture.

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