PDA

View Full Version : Sun-thickened Linseed Oil


canvasishome
07-27-2000, 08:53 AM
Good Morning,
Can someone give me advice as to what I may be doing wrong here? I have read several sources that give instructions on how to make sun-thickened linseed oil. Here is what I have been doing:
I put about 2-3 oz. of oil in a large, uncovered glass jar. The oil only sits about 1/4" deep in the bottom. I have "roasted" the oil in the 100+ degree Texas sun for 2 weeks. I have read where the oil should form a slight skin and the brew is stirred every few days. The result should be a honey-like oil. My results have only thickened the oil slightly and I've never had any skin develop. What am I doing wrong? Oil too deep? Not enough baking time?
p.s. My reason for doing this is to add this to my paint for a glossier finished look. Do I understand correctly that this is what this is used for?
Many thanks, as always!
DK

esartstudio
07-27-2000, 04:28 PM
Hello,

Sun Thickened oil is a wonderful thing to add to your painting. Besides giving a glossy look and adding body to your paint, it speeds up the drying time because the oil has already started to dry.

The process of making this oil can take quite some time, a few weeks.

You could try making the layer of oil even thinner by putting it in a jar with a wider base.

To get is truly as thick as honey or "stand-oil" will take even longer!

Regards,

Ethan Semmel
==================================
Learn the Secrets of Oil Painting (http://www.esartstudio.com/cgi-bin/affiliates/clickthru.cgi?id=oilpainta)

Titanium
07-27-2000, 07:08 PM
Hello DK ,

you need at least 6 weeks , and after the end of the 2nd week , start stirring , in the morning . After another week , this will be twice a day . Eventually to get to honey thick you will be stirring 4 to 6 times a day .
Test the drying capacity , with a drop on glass . I stop when the drop dries overnight.
[ When I used sun thickened oil . ]

Use the stuff sparingly , can make for very gooey painting.
Also acts as a drier in paintings.

Word of caution , there is no scientific proof [ examined paintings ] showing the use of sun thickened oil in paintings . In varnishes for wood - yes , but thus far in old paintings , it is straight linseed/walnut oil , or an early stand oil type .

Don't take my word for it see the National
Gallery [ London ] Technical Bulletin .

Sun thickened oil , may actually cause a painting to age badly , cracking and darkening .

If you not interested in Longevity , well , enjoy yourself , it's a great oil to work
in . You can also sun thicken Walnut as well.
Best to you ,
Titanium .

rhoward
07-29-2000, 11:56 PM
Sun-thickened oil ages very badly, perhaps the worst of all oils. Stand oil, on the other hand, has very different molecular properties and when thinned to a useful consistency appears to be the least yellowing of all oils.

I realise that's not in keeping with the myth, but that has been proven in numerous tests.

------------------
Cennini Catalogue http://studioproducts.com/quickcatalog/catalogframes.html

Vincent40
05-22-2010, 01:05 PM
I do not realy understand why it can give extra cracking, it is still linseed oil and about drying.

If you don't push it by thickening it to much there is not much diffrent in regular linseed oil.

From the 14th century till now it has been used by many artists, even Rubens did decribed it as the best oil you could get.

Hello DK ,

you need at least 6 weeks , and after the end of the 2nd week , start stirring , in the morning . After another week , this will be twice a day . Eventually to get to honey thick you will be stirring 4 to 6 times a day .
Test the drying capacity , with a drop on glass . I stop when the drop dries overnight.
[ When I used sun thickened oil . ]

Use the stuff sparingly , can make for very gooey painting.
Also acts as a drier in paintings.

Word of caution , there is no scientific proof [ examined paintings ] showing the use of sun thickened oil in paintings . In varnishes for wood - yes , but thus far in old paintings , it is straight linseed/walnut oil , or an early stand oil type .

Don't take my word for it see the National
Gallery [ London ] Technical Bulletin .

Sun thickened oil , may actually cause a painting to age badly , cracking and darkening .

If you not interested in Longevity , well , enjoy yourself , it's a great oil to work
in . You can also sun thicken Walnut as well.
Best to you ,
Titanium .

Ron Francis
05-22-2010, 07:52 PM
Vincent,
This thread is 10 years old!

Vincent40
05-23-2010, 04:21 AM
And the technique sun thickening linseed oil was first described by
Celini in 1390 !
:thumbsup:

Curran
10-26-2012, 02:01 PM
WOAH! Sun thickened oil doesn't age well? That's bull____
Sun thickened oil was taught as the oil par excellence for generations since Ceninno Ceninni. Peter Paul Rubens and Da Vinci both made their own and exclusively used sun thickened oil and both of their paintings which are in EXCELLENT condition.

Go read two sources on painting crackings, books by Gustave Berger and Knut Nicolaus. Both of them state specifically 'cracking is a result of atmospheric conditions that effect canvas sizing to shrink and then relax'. These seasonal expansions and contractions cause cracks because the paint film is brittle.

As for your sun thickened oil; it takes some time. I do know that the process is helped when you mix the oil with equal parts water and shake it thoroughly. You can allow the water to stand on it while it thickens or freeze the water and pour your oil off and let it thicken some more. The water removes some of the fatty acids from the oil. Other than that just stir it twice a day, checking it once a week for consistency. And you can get it VERY thick, like molasses. It makes the BEST glazing medium.

One last tip. You will likely get bugs, pollen, airborne particles. So it is recommended that you filter it before you use it. Through a painfully long process of experimentation I have found that filtering is much easier if you heat the oil a glass container in a hot water bath-like what you do with your rabbit skin glue sizing-then filter it through a cloth.

That's it! Enjoy!

Ron Francis
10-26-2012, 11:02 PM
The argument against sun thickened oil, according to Mayer, is that it has already partly oxidised which will have an adverse effect on adhesion.
Of course this lessening of adhesion may be insignificant, especially compared to other techniques like beginning with an initial layer of paint diluted with solvent.
Still, if one doesn't need the viscosity and faster drying time, then I can't see any reason to use it.
Stand oil is viscous and much more stable in that it forms a more elastic and and less yellowing film. (It takes much longer to dry though.)