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Peter K-G

"Siccative" linseed oil without sun

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I'm really happy with my last batch of varnish and linseed oil, so I want to share how to get good siccative linseed oil in countries where there is no sunshine.

 

Finnish (or Swedish) cold pressed linseed oil boiled at steady temperature for 4,5 hours ~95 C.

 

The jar stands on a piece of wood

 

post-37356-0-91950900-1392271645_thumb.jpg

 

The varnish/linseed oil dries niecelly over night in UV box

 

http://www.maestronet.com/forum/index.php?/topic/328430-peter-kgs-bench/page-8#entry605324

http://www.maestronet.com/forum/index.php?/topic/328430-peter-kgs-bench/page-8#entry605355

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Hi Peter-  This is a report in Journal Chemistry and Industrial Engineering, 1951:vol29,581    that might explain your results from heating the linseed oil. Even though the temperature in this study was much higher, 275-280oC (ca 520oF), the results are similar. The oil was heated for 6 hrs at this temperature and it changed non-oxygen-convertible  mono and diglycerides bonds into oxygen-convertible forms that would favor condensation and polymerization. Also states large surface exposure important. Luckily MN has an expert  organic chemist and hopefully he can  explain some of the terminology. Basically it is saying that heat changes bonds in linseed oil that favors solidifying.  fred

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There is no such siccative as artificial UV light. I assume most modern violin makers have a UV box.

Traditionally painters have added mastic, and if you read a recent post here by Roger Hargrave, you will find, he does the same.

Nobody knows why mastic speeds up linseed oil polymerisation. The chemistry of this is not well understood. There must be radicals that speed up the polymerisation of linseed oil, as it is clearly a photopolymerisation, but this can't be how mastic works. I assume that it enables a copolymerisation that causes faster (although almost certainly) different hardening.

Mastic is also part of some more complex spirit varnishes, and was part of Bisiach later varnish.

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Fred, Thanks for the chemistry lesson.

 

uguntde, I have read Rogers posts on varnishing in his double bass topic over and over again, who hasn't. Where I live there is no sunshine this time of the year ,so I'v built myself a simple UV box, like all other makers who cure oil varnish.

 

post-37356-0-48369300-1392655937_thumb.jpg

 

My varnish dries over night in the UV box to the degree that the violin can be hold and put on the next layer. This is because I have pre boiled the linseed oil for 4,5 hours before I cook it into varnish. The same linseed oil without pre boiling dried much slower.

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... a report in Journal Chemistry and Industrial Engineering, 1951:vol29,581    that might explain your results from heating the linseed oil. 

I cannot find this. I think your citation has errors.

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Post #5- That article was abstracted about 25 years ago from the actual Journals in the Marine Biological Laboratory, Marine Science Library(largest in the world), located across the street where I was employed. The journal from which the article was referenced underwent 3 title changes from 1898 and presently has another title and most likely I  used JSCI (journal Society Chemical Industry) to articles abstracted for quick reference, ignoring the possible journal title at that time. About 15 years ago MBL sold off these journals for need of space so I'm not able to check with the actual journal. Here are some others you can check to see if they are real-

 

JSCI- 1905:1064-Dyeing/aging wood

JSCI-(no date) 3:181- Linseed oil-drying 

JSCI- !885-6(?)- Copal-dissolving   Amber- coloring

JSC-vol 17:469-copal resinates as driers

JSCI- vol 3:370- extracting wood colors

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Fred, Thanks for the chemistry lesson.

 

uguntde, I have read Rogers posts on varnishing in his double bass topic over and over again, who hasn't. Where I live there is no sunshine this time of the year ,so I'v built myself a simple UV box, like all other makers who cure oil varnish.

 

attachicon.gifUV_Chamber.jpg

 

My varnish dries over night in the UV box to the degree that the violin can be hold and put on the next layer. This is because I have pre boiled the linseed oil for 4,5 hours before I cook it into varnish. The same linseed oil without pre boiling dried much slower.

 

I also have the impression the frequency of UV light is important. UVC (the sorter wave length) can kill the varnish (although sun light has lots of UVC). Many use UVC to darken the wood. UVB is however somewhat too soft.

 

Journal Chemistry and Industrial Engineering I can't find.

 

I however find:

T.F. Bradley. Drying Oils and Resins Structure upon Oxygen and Heat Convertibility.  Industrial & Engineering Chemistry 29(5), 579-584.

 

This is an ACS journal, all early issues digitised.

 

Is this what is meant? The journal abbreviation JSCI stands for Journal of Scientific Instruments. This can't be it.

The other articles I can't guess.

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Thank you Uguntde (post 7)- on the bib card I had Journal included with "Industrial & Engineering Chemistry", so it was under a different Journal title  of the journal titles  I copied. It is the article I was referring to. I'm pretty sure it refers to changes that induce solidifying of the oil, and hopefully you are able to simplify the chemical terminology portion  I included in the post. I guess all the other titles I included also have to be matched to the respective title in extant at the time.  Again, thanks.   fred

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I'm really happy with my last batch of varnish and linseed oil, so I want to share how to get good siccative linseed oil in countries where there is no sunshine.

 

Finnish (or Swedish) cold pressed linseed oil boiled at steady temperature for 4,5 hours ~95 C.

 

The jar stands on a piece of wood

 

attachicon.gifBoilingLinseed16112013.jpg

 

The varnish/linseed oil dries niecelly over night in UV box

 

http://www.maestronet.com/forum/index.php?/topic/328430-peter-kgs-bench/page-8#entry605324

http://www.maestronet.com/forum/index.php?/topic/328430-peter-kgs-bench/page-8#entry605355

You can even pour linseed oil in shallow plates (1 or 2 mm thick layers) and leave it like this near your window for few weeks, mixing from time to time. You will see the oil getting thicker, and it will dry faster once you make a varnish out of it. But of course a UV chamber renders this step unnecessary.

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Hi Peter-  This is a report in Journal Chemistry and Industrial Engineering, 1951:vol29,581    that might explain your results from heating the linseed oil. Even though the temperature in this study was much higher, 275-280oC (ca 520oF), the results are similar. The oil was heated for 6 hrs at this temperature and it changed non-oxygen-convertible  mono and diglycerides bonds into oxygen-convertible forms that would favor condensation and polymerization. Also states large surface exposure important. Luckily MN has an expert  organic chemist and hopefully he can  explain some of the terminology. Basically it is saying that heat changes bonds in linseed oil that favors solidifying.  fred

 

I have a bottle of "Stand Oil" I bought from the Art Supply store near my house.  It has been heated in a vacuum until thick (polymerized) and so it apparently dries faster.  Fred, I think you recommended using this for a varnish batch. Which I was about to do.

 

Joe

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I have a bottle of "Stand Oil" I bought from the Art Supply store near my house.  It has been heated in a vacuum until thick (polymerized) and so it apparently dries faster.  Fred, I think you recommended using this for a varnish batch. Which I was about to do.

 

Joe

Joe,

Stand Oil is highly polymerized in a vaccumn.  This process inhibits oxidation...drying.  This material is not suitable for violin varnish.

Joe

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Joe,

Stand Oil is highly polymerized in a vaccumn.  This process inhibits oxidation...drying.  This material is not suitable for violin varnish.

Joe

 

Hmmm... I'm positive it was recommended in a previous post.  That's why I bought a bottle. Guess I ought to return it.  :rolleyes: 

But reading the bottle it definitely says it will slow down the drying time.  Thanks for jumping in and correcting my error.  :D 

 

So Joe, is there an advantage of heating the oil and heating the rosin separately then before combining them?  It seems once they are mixed together you have to take the batch off the heat once it starts tacking up.  If done separately you can thicken the oil as described, possibly add pigment ingredients to get the colors going.  Heat the rosin separately to oxidize and darken it before combining everything to make the final varnish?  

 

Thanks,

Joe

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Hmmm... I'm positive it was recommended in a previous post.  That's why I bought a bottle. Guess I ought to return it.  :rolleyes: 

But reading the bottle it definitely says it will slow down the drying time.  Thanks for jumping in and correcting my error.  :D 

 

So Joe, is there an advantage of heating the oil and heating the rosin separately then before combining them?  It seems once they are mixed together you have to take the batch off the heat once it starts tacking up.  If done separately you can thicken the oil as described, possibly add pigment ingredients to get the colors going.  Heat the rosin separately to oxidize and darken it before combining everything to make the final varnish?  

 

Thanks,

Joe

 

Joe,

Pre-processing the linseed oil, and, or, the resin prior to making the varnish gives you much greater control over the varnish outcome.

Joe

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You can even pour linseed oil in shallow plates (1 or 2 mm thick layers) and leave it like this near your window for few weeks, mixing from time to time. You will see the oil getting thicker, and it will dry faster once you make a varnish out of it. But of course a UV chamber renders this step unnecessary.

 

Last summer I did some interesting tests that at least for me was pretty convincing. The best choice would be Traditional cold pressed linseed oil.

 

Edible (Salad linseed oil), Traditional cold pressed and Refined linseed oil from Kremer

 

post-37356-0-17840100-1392823885_thumb.jpg

 

After a day or so outside (not direct strong sun light), The Traditional cold pressed oil (Finnish quality) had lost all the yellowness and started to polymerize. Next to polymerize was the edible linseed oil (2,5 Days). Refined Kremer took 4-5 days to get the same thickness. All of them lost their yellowness in the end, Refined Kremer was the last one, even if the edible linseed oil was more yellow from the beginning and for 3 days.

 

So Traditional Cold pressed after ~1,5 days totally white and quite thick.

 

post-37356-0-69718600-1392823990_thumb.jpg

 

As a side note Refined Kremer oil collected flyes - good or bad, no idea :)

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Joe,

Pre-processing the linseed oil, and, or, the resin prior to making the varnish gives you much greater control over the varnish outcome.

Joe

 

Thanks Joe...

 

Last summer I did some interesting tests that at least for me was pretty convincing. The best choice would be Traditional cold pressed linseed oil.

 

Edible (Salad linseed oil), Traditional cold pressed and Refined linseed oil from Kremer

 

attachicon.gifLinseedOil.jpg

 

After a day or so outside (not direct strong sun light), The Traditional cold pressed oil (Finnish quality) had lost all the yellowness and started to polymerize. Next to polymerize was the edible linseed oil (2,5 Days). Refined Kremer took 4-5 days to get the same thickness. All of them lost their yellowness in the end, Refined Kremer was the last one, even if the edible linseed oil was more yellow from the beginning and for 3 days.

 

So Traditional Cold pressed after ~1,5 days totally white and quite thick.

 

attachicon.gifFlyesInLinseedOil.jpg

 

As a side note Refined Kremer oil collected flyes - good or bad, no idea :)

 

Interesting... So is this "oxidation"?  I would think it would get darker... The fly is probably random...

 

I can reproduce the fly part of the experiment with a hot cup of coffee.  Occasionally, I only find out too late.  :wacko:  :blink:

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Joe S (post 10)- I have never used any oil except untreated oil, so I don't think I suggested it, I hope. Sometimes, to see the results, I will use the boiled oil you buy in a pint can, which has manganese and cobalt for driers.  If I make a copal resin based varnish you can't combine resin and oil for the oil will gel before the copal is depolymerized. With rosin, I mix them all together for I think you have to drive off all the trash in rosin and get to around 580oF, just under the temp where Bloom oil (fluorescent yellow)  would distill off. My thinking is the  linseed oil also has to be heat bodied to "string phase,"  may as well mix them. Post #2 supposedly describes technically what happens when you heat linseed oil, so I was hoping someone can put it into, as Joe R says) for cooks to understand.  fred

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Joe S (post 10)- I have never used any oil except untreated oil, so I don't think I suggested it, I hope. Sometimes, to see the results, I will use the boiled oil you buy in a pint can, which has manganese and cobalt for driers.  If I make a copal resin based varnish you can't combine resin and oil for the oil will gel before the copal is depolymerized. With rosin, I mix them all together for I think you have to drive off all the trash in rosin and get to around 580oF, just under the temp where Bloom oil (fluorescent yellow)  would distill off. My thinking is the  linseed oil also has to be heat bodied to "string phase,"  may as well mix them. Post #2 supposedly describes technically what happens when you heat linseed oil, so I was hoping someone can put it into, as Joe R says) for cooks to understand.  fred

 

What temp is best to preheat the linseed oil, if one is disposed to doing so?  So as to thicken and start the oxidation process... Maybe better to ask what is the Max temp NOT to preheat to?  

 

It seems like if the preheat is hotter than Peter's 95 deg C it will go "faster"...  but at some point (temp) it will turn to "goo"... :blink:

I'm going to check the Building a Bass thread as I thought Roger mentioned that specific in there somewhere. 

 

Thanks again!

^_^

Joe

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Here-in lies the secret:

 

Almost any combination will form varnish, just put whatever colophony, whatever linseed oil and whatever proportions in a pan and show it some heat.

 

Voila violin varnish. Good? you will know after 15 years or so ;)

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Hi Joe S (post 17)- Peter is right, eventually anything will form a coat, but what is desirous is reducing the time to be able to string up the inst  within  maybe a week or so after varnishing.  Spread out some linseed oil, expose it to air and it will form a hardened film on the surface in a week (guessing). As temperature is raised the time to form a film is reduced, so  to not wait forever before the inst can b e strung up, the temp's  are increased. It takes me just over an hour from start to filter to make a copal varnish because the working temp is ca 600oF, and as mentioned earlier, oil is added after the copal resin is cracked, for at that temp it isn't long before oil will start to gel. Making a rosin varnish is about the same time, temp is around 580oF and oil and rosin are combined. The importance of the temp's is that they will create a surface foam which tells what is going on in the mixture. When the foam starts to be reduced this indicates that bonds in the oil have been converted so that spreading out in a film will dry in a fairly short time, depending on how much oil was used, less oil, shorter time to tack free. Getting that foam, whatever temp is used, is the key to end of cook.  fred

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Hi Joe S (post 17)- Peter is right, eventually anything will form a coat, but what is desirous is reducing the time to be able to string up the inst  within  maybe a week or so after varnishing.  Spread out some linseed oil, expose it to air and it will form a hardened film on the surface in a week (guessing). As temperature is raised the time to form a film is reduced, so  to not wait forever before the inst can b e strung up, the temp's  are increased. It takes me just over an hour from start to filter to make a copal varnish because the working temp is ca 600oF, and as mentioned earlier, oil is added after the copal resin is cracked, for at that temp it isn't long before oil will start to gel. Making a rosin varnish is about the same time, temp is around 580oF and oil and rosin are combined. The importance of the temp's is that they will create a surface foam which tells what is going on in the mixture. When the foam starts to be reduced this indicates that bonds in the oil have been converted so that spreading out in a film will dry in a fairly short time, depending on how much oil was used, less oil, shorter time to tack free. Getting that foam, whatever temp is used, is the key to end of cook.  fred

 

I was more questioning the temp and time used in pre-heating the oil (and also rosin) prior to mixing the two together.  

 

I made a second batch of varnish today using more burnt umber than last time as you mentioned in a earlier thread of mine.  Also preheated the rosin adding some Calcium Carbonate to help neutralize the ph and pre heated the oil adding the burnt umber before adding the heated oil too the molten rosin in the big pot.  Went very well. Have to see how it looks in some test strips.  Definitely browner than the last batch.  Still the same aloe component.  SO it is still supposedly red-brown.

 

Thanks!

Joe

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The key is to burn off all the fat so that you are left with the pure oil only. I would be interested to know what approach you take to insure that the fat indeed is all gone.

The old masters, according to Geary Baese, used a Goose feather for testing. Is this what you use?

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The key is to burn off all the fat so that you are left with the pure oil only. I would be interested to know what approach you take to insure that the fat indeed is all gone.

The old masters, according to Geary Baese, used a Goose feather for testing. Is this what you use?

 

Well... Not anymore.. The neighbor got a restraining order.  I can't get within 100 yards of their goose any more. :huh:

 

Although its no real secret, I heated the oil with burnt umber already mixed in for a few hours, gradually raising the temp up to the point it started "smoking" ~200 dec C.  And I heated the rosin with the 5% Lime (CaCO3) up to similar temperatures - although the lime didn't see to dissolve readily.  I let it simmer and smoke in it's own pot for 10 min or so and then added the hot oil.  

 

That really is a lot safer than the last time - (A la Adele Beardsmore Strad Trade Secrets Article on making varnish) adding the dry rosin to the hot oil caused significant foaming and the possibility of spill-over was more likely.  This time it just continued to simmer away quietly and safely.  Only foaming occurred when adding the aloe powder.  Maybe I'll try adding this to the oil with the burnt umber separately next time.

 

Joe

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Joe- I'd advise not adding lime (CaOH)  because you want the acidity of the rosin to react with the Umber to form a resinate  with the metals present in Umber,- Manganese Mn, Iron Fe, and Aluminum Al. These form the colors and act as driers that speed up the time to Tack Free condition. You have a thermometer, so just as an experiment, combine, (to this ratio, for I only make 15 grams of dark rosin, 10 grams of linseed oil, say 1/4inch tube Umber) , to the amounts used in your set up. As you get into the cook, watch the temp and what it is when you see tiny islands of foam running to the edge, this is the start of fast bond conversion in linseed oil and undoubtedly reactions also among all 3. You have to  make certain to get a sufficient foam cover, maybe slightly under 1/4 inch, so that when reactions are ending (foam disappearing), you don't get confused with your hot plate going on and off. Get this down pat so  you have a standard to which you can compare any changes you make. Thin with turp when under 450 so that a drop on glass will run into a doughnut. Since I use dark rosin, my varnish coats go from yellow to reddish brown in about 3-4 coats.  I hope you do this so there is someone to verify or correct the stuff I posted.  fred 

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.

The old masters, according to Geary Baese, used a Goose feather for testing. Is this what you use?

A goose feather, passed over the surface but not touching, will disappear [save for the quill] when the temperature is 273C.

Be careful,

Joe

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