Making boiled linseed oil for use in varnish making

[Jimlad]

For what it is worth - I remember about 50 years ago reading a specification clause that said " ... bolts shall be boiled in linseed oil.."

[Davide Sora]

3 hours ago, Jimlad said:

For what it is worth - I remember about 50 years ago reading a specification clause that said " ... bolts shall be boiled in linseed oil.."

Bolts? Maybe some sort of anti-rust treatment?

[Michael_Molnar]

 

[Davide Sora]

1 hour ago, Michael_Molnar said:

 

Thanks Michael. But damn, cooked at 400 °, if it is celsius I thought that the linseed oil should be burned completely.

Well, not for violins...

[Bill Yacey]

I guess we need to consider " When the ancient texts speak of boiled linseed oil, do they mean literally boiled, or simply heated to an arbitrary temperature? Boiled seems more like an absolute term.

[Davide Sora]

37 minutes ago, Bill Yacey said:

I guess we need to consider " When the ancient texts speak of boiled linseed oil, do they mean literally boiled, or simply heated to an arbitrary temperature? Boiled seems more like an absolute term.

I think your second guess is more likely, boiled I think it was anciently used simply to mean heated over a fire or some source of heat.

This is an interesting article on temperature control systems before the thermometer came into common use:

https://recipes.hypotheses.org/11275

[Michael Szyper]

17 hours ago, Davide Sora said:

Thanks Michael. But damn, cooked at 400 °, if it is celsius I thought that the linseed oil should be burned completely.

Well, not for violins...

My sandarac oil varnishes can reach 380°C and the result are quite fine. Nevertheless, I don't see a reason to boil the linseed oil for itself in these high temperatures. 

[JacksonMaberry]

7 hours ago, Michael Szyper said:

My sandarac oil varnishes can reach 380°C and the result are quite fine. Nevertheless, I don't see a reason to boil the linseed oil for itself in these high temperatures. 

Lemme see your sandarac! I've only played with sandarac oil varnish once, and in cooking the resin in little batches, it was the batches that reached 350° and higher that actually cooked into oil. Anything lower would not incorporate.

 

Really blast from the past seeing this thread! I have learned an awful lot since then.