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uguntde

Choice of linseed oil

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Linseed oil comes in many varieties. Apparently the sun-bleeched refined (73300 Kremer) is believed the make faster drying varnishes. The also offer cold pressed (73054 Kremer Linseed Oil). And there are many others on the market. Does the refined oil still require 2-3h of cooking?

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4 hours ago, uguntde said:

Linseed oil comes in many varieties. Apparently the sun-bleeched refined (73300 Kremer) is believed the make faster drying varnishes. The also offer cold pressed (73054 Kremer Linseed Oil). And there are many others on the market. Does the refined oil still require 2-3h of cooking?

I used Gamblin cold pressed linseed oil from my local craft store for my damar varnish. I cooked it for two hours at just under 500f. 

The varnish dries in about 36 hours with a fairly thick coat under artificial blacklight UV.

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12 hours ago, lpr5184 said:

The labels peel off easily from the 5 L  jugs....:)

I should've deduced that... The one is just a maple syrup bottle...

I never cease to amaze myself sometimes.

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On 9/10/2018 at 6:16 PM, lpr5184 said:

My choice is  AllBack, Swedish, Raw Organic Linseed. When well washed it dries fast and makes great varnish.

http://www.solventfreepaint.com/cleaned_linseed_oil.htm

004.JPG.84fe36fd318d31176b086df1fed98b5a.JPG

 

What is "well-washed" ? 

In a quite well-known painting textbook  ( Max Doerner or Kurt Wehlte ) the author writes, that a fine linseed-oil in a quite thin layer ( on glass, if I remember right)  has to dry completely within 5 days and without any longer sticking. In my own experiments I never could reach this condition with a pure linseed oil, also not after washing with pure water several times and also later sun-thickening. Did you suceed in reaching such a condition ( finally not sticking ) without using driers ?

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7 hours ago, lpr5184 said:

Yup....What brand of oil did this happen with?

In case you missed it in the other thread...read this

https://www.tadspurgeon.com/content.php?page=just+oil

Thanks, Ernie. I know it is important for psychological reasons to chew over ideas. I too need to do that.  Nevertheless, there are lots of great earlier posts and  I wonder whether posters did a search on Maestronet before asking a question that has been discussed ad nauseam. The Tad Spurgeon website is gold and cited earlier here on Maestronet. Thanks for reminding us.

In this era of misinformation,  one red herring that stands out is the claim that the search feature on Maesteronet is worthless. That was true, but I find the.latest version to be a powerful tool if you take the time to learn how to use it. I will be 73 in 2 days and continue looking for new tools and ideas. I like the Maestronet search feature because I took the time to learn how to use it.  :P

Please do not think that I am putting down posts from younger/newer members who are asking questions we asked years ago.  All I am trying to do is help them find the gold mine on Maestronet. Nevertheless, I am upset with my colleagues who claim that the search feature is worthless.

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5 hours ago, lpr5184 said:

Yup....What brand of oil did this happen with?

In case you missed it in the other thread...read this

https://www.tadspurgeon.com/content.php?page=just+oil

Thanks ! 

Indeed this site is not new for me - I have read the several methods of oil-treating some years ago but decided to try only the pure water-washing method without any heat, which is also described by Tad Spurgeon. Later the oil was sunthickened. The result was a quite fast drying oil, not yellowing very much - but it remains sticky after years, if used without resins. In combination with resin it becomes nearly non-sticky. In the whole thing I didn´t apply heat - maybe this would have helped.

Possibly I should try sand and salt - probably this would make quite a difference. However I also was told that a pure linseed oil ( without driers ) would never stop to remain sticky and so I stopped further experiments. Even an experiment  with a commercial treated painters oil failed in drying without stickiness. You are the first person, who tells me to be able to produce a non-sticky pure linseed oil. So I have to do some new experiments. 

What I always was wondering : my self-made oils used as a ground dry completely on the wood-surface without staying sticky - I don´t have any idea, why. The same oil applied on glass remains sticky.

 

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Well for what it is worth, I use the hot water, salt and sand method described by Spurgeon to wash and then use heat very slowly under 212 degrees (the boiling point of water) to clear the final oil.

Depending on the thickness of the coat, the washed .oil dries in 1-2 days.  It is still flexible as it should be but definitely not sticky, wet or greasy.

I'd really like to know what brand of oils you have tried that remain sticky after washing?...The Allback oil is made for the paint and varnish industry.

Where you perhaps using food grade linseed oil? Some of those I'm told will not dry no matter what you do.

All I know is the method works well for me but it is a chore that I almost dread doing. It's a lot of messy physical work and you lose between 30-40 percent depending on the quality of the oil.

I'm very glad to see the new updated large quantity method and added refining procedures in the Spugeon .pdf

Another great reference book is...

http://www.alchemistmediums.com/products_book.php

 

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Strad obviously had access to highly refined oils?

Really when I look at great old violins or talk to my most highly respected colleagues in the making or restoring fields the search is not for something perfect, solid or modern .. rather it is for fallible ingredients that render a colored but very fragile varnish

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14 hours ago, Melvin Goldsmith said:

Strad obviously had access to highly refined oils?

Really when I look at great old violins or talk to my most highly respected colleagues in the making or restoring fields the search is not for something perfect, solid or modern .. rather it is for fallible ingredients that render a colored but very fragile varnish 

The practice of sun thickening of linseed oil is very old indeed. Strad may very well have used refined oil, just with the methods available then. Abour Kremer I read somewhere that they have someone in the Alps who sunthickens oil for them in large flat metal containers. I assume this is what they sell as refined linseed oil.

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16 hours ago, lpr5184 said:

Well for what it is worth, I use the hot water, salt and sand method described by Spurgeon to wash and then use heat very slowly under 212 degrees (the boiling point of water) to clear the final oil.

Depending on the thickness of the coat, the washed .oil dries in 1-2 days.  It is still flexible as it should be but definitely not sticky, wet or greasy.

I'd really like to know what brand of oils you have tried that remain sticky after washing?...The Allback oil is made for the paint and varnish industry.

Where you perhaps using food grade linseed oil? Some of those I'm told will not dry no matter what you do.

All I know is the method works well for me but it is a chore that I almost dread doing. It's a lot of messy physical work and you lose between 30-40 percent depending on the quality of the oil.

I'm very glad to see the new updated large quantity method and added refining procedures in the Spugeon .pdf

Another great reference book is...

http://www.alchemistmediums.com/products_book.php

 

Thanks a lot for detailed informations ! 

Indeed I used  high-food-grade linseed oil, several brands. My idea was, that only such a ( bio-quality) foot-grade oil ( cold-pressed ) would represent a sufficient original oil- quality - so I would have total control over all processing things happening with this oil.  However now, after several new knowledge even about the bio-nutrition-industry I don´t trust any longer, that cold-pressed bio-linseed oil is really a natural oil without supplements. One has to know, that the nutrition-interests in oil-processing are completely contrary to the interests of the varnish- industry. The nutrition - industry wants to do all possible things to avoid oxidation/polymerisation - may be they add some substances to reduce these reactions but don´t declare it or use physical procedures with similar effects. Another thing could be special varíeties of linseed, optimized for the use as varnish but therefore unsuitable as food.

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16 hours ago, Melvin Goldsmith said:

Strad obviously had access to highly refined oils?

 

1 hour ago, uguntde said:

The practice of sun thickening of linseed oil is very old indeed. Strad may very well have used refined oil, just with the methods available then. Abour Kremer I read somewhere that they have someone in the Alps who sunthickens oil for them in large flat metal containers. I assume this is what they sell as refined linseed oil.

Since linseed oil was frequently used in old varnishes, it is probable, that they had good methods for preparation.However I never have read an old recipe without resins - so eventually they didn´t have a sufficient procedure resulting in a pure linseed-varnish without driers or resins. May be they could live and work without it. 

As I told, I am still wondering, why my sticky-staying oil dries completely not-sticky on wood-surfaces. May be, that the wood provides substances for the total drying ?

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1 hour ago, Danube Fiddler said:

Thanks a lot for detailed informations ! 

Indeed I used  high-food-grade linseed oil, several brands. My idea was, that only such a ( bio-quality) foot-grade oil ( cold-pressed ) would represent a sufficient original oil- quality - so I would have total control over all processing things happening with this oil.  However now, after several new knowledge even about the bio-nutrition-industry I don´t trust any longer, that cold-pressed bio-linseed oil is really a natural oil without supplements. One has to know, that the nutrition-interests in oil-processing are completely contrary to the interests of the varnish- industry. The nutrition - industry wants to do all possible things to avoid oxidation/polymerisation - may be they add some substances to reduce these reactions but don´t declare it or use physical procedures with similar effects. Another thing could be special varíeties of linseed, optimized for the use as varnish but therefore unsuitable as food.

Makes sense why the oil didn't dry. Better to stick with the known brands of varnish making oils.

 

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Well, some of this may have been discussed before, but many questions also remain unanswered.

1 hour ago, Danube Fiddler said:

 

Since linseed oil was frequently used in old varnishes, it is probable, that they had good methods for preparation.However I never have read an old recipe without resins - so eventually they didn´t have a sufficient procedure resulting in a pure linseed-varnish without driers or resins. May be they could live and work without it. 

As I told, I am still wondering, why my sticky-staying oil dries completely not-sticky on wood-surfaces. May be, that the wood provides substances for the total drying ?

I am not a vaarnish expert, but this is my underdstanding from reading up some of the chemistry. Linseed oil is like any oil a glycerol ester with three fatty acid groups: linoleic acid, alpha-linolenic acid, and oleic acid. Two of them have conjugated double bonds (linoleic acid and alpha-linolenic). When we cook varnish we cook with with abeietic acid, which also has a carboxylic acid group and conjugated double bonds.  

When we just cook linseed oil we change the arrangement of these conjugated double bonds, as it seems for the better. More conjugation = better drying.

When we cook linseed oil with a base or an acid it will get saponified, i.e. the ester bond between the carboxylic acid end group and the glycerol gets split. As product we get glycerol and theree fatty acids. If we now cook with abeietic acid we can esterify the same with glycerol and get abeietic/inoleic acid, alpha-linolenic acid, and oleic acid mixed glycerol esters ( glyceryl abietate or ester gum). The longer free fatty acids will in this mixture act as solvent for the ester gum.

This is why the reaction between rosinate and oil goes vigorous and faster with ash water  and lime - this acts as a base catalyst for the esterification. In my experience it goes even faster with a frop of acid.  I saw a massive exothermal reaction with both.

When we expose to light we get a reaction between our fatty acids and fatty acid esters with conjugated bonds with each other. This is a light induced so-called Diels-Alder reaction (a common chemical reaction, the can be light or heat induced leading to a different stereochemistry). The outcome is a complex cross linked structure. This happens during the process of hardening.

The same can of course also be done with just the two fatty acids from linseed oil that have conjugated double bonds - this is why this will also dry. But having 50% of extra material that can be cross linked helps, and the abietic acid structure will also give a material with a higher boiling point.

There is a huge body of literature about this, a lot of it buried in old patents. 

I should say that I am an analytical chemist, but know not much about polymers and varnishes. Some of what I just wrote is guess work based on basic organic chemistry, but I did read a few articles when I folloed the discussion about UV photography (conjugated double bonds absorb UV and show fluorescence). Happy to be proven wrong, maybe there are other chemist out there in the violin world and we get some discussion about what these varnihes are.

I have also recently compared differnt linseed oils and I may carry out some chemical analysis to find out what happens when I boil the oil. I m ay report the outcomes at a a later time. My main interest was drying efficiency.

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50 minutes ago, uguntde said:

Well, some of this may have been discussed before, but many questions also remain unanswered.

I am not a vaarnish expert, but this is my underdstanding from reading up some of the chemistry. Linseed oil is like any oil a glycerol ester with three fatty acid groups: linoleic acid, alpha-linolenic acid, and oleic acid. Two of them have conjugated double bonds (linoleic acid and alpha-linolenic). When we cook varnish we cook with with abeietic acid, which also has a carboxylic acid group and conjugated double bonds.  

When we just cook linseed oil we change the arrangement of these conjugated double bonds, as it seems for the better. More conjugation = better drying.

When we cook linseed oil with a base or an acid it will get saponified, i.e. the ester bond between the carboxylic acid end group and the glycerol gets split. As product we get glycerol and theree fatty acids. If we now cook with abeietic acid we can esterify the same with glycerol and get abeietic/inoleic acid, alpha-linolenic acid, and oleic acid mixed glycerol esters ( glyceryl abietate or ester gum). The longer free fatty acids will in this mixture act as solvent for the ester gum.

This is why the reaction between rosinate and oil goes vigorous and faster with ash water  and lime - this acts as a base catalyst for the esterification. In my experience it goes even faster with a frop of acid.  I saw a massive exothermal reaction with both.

When we expose to light we get a reaction between our fatty acids and fatty acid esters with conjugated bonds with each other. This is a light induced so-called Diels-Alder reaction (a common chemical reaction, the can be light or heat induced leading to a different stereochemistry). The outcome is a complex cross linked structure. This happens during the process of hardening.

The same can of course also be done with just the two fatty acids from linseed oil that have conjugated double bonds - this is why this will also dry. But having 50% of extra material that can be cross linked helps, and the abietic acid structure will also give a material with a higher boiling point.

There is a huge body of literature about this, a lot of it buried in old patents. 

I should say that I am an analytical chemist, but know not much about polymers and varnishes. Some of what I just wrote is guess work based on basic organic chemistry, but I did read a few articles when I folloed the discussion about UV photography (conjugated double bonds absorb UV and show fluorescence). Happy to be proven wrong, maybe there are other chemist out there in the violin world and we get some discussion about what these varnihes are.

I have also recently compared differnt linseed oils and I may carry out some chemical analysis to find out what happens when I boil the oil. I m ay report the outcomes at a a later time. My main interest was drying efficiency.

While I can´t contribute to the chemical things, you just described - I assume, there could be two partially independent things : a) drying and b) loosing stickiness.     In my experience oil can dry quite a lot, but can stay sticky. My idea is, that the reason could be a certain critical component of the oil, which must get removed or destroyed. This component could be any substance soluble in fats and regularly existent in most kinds of plant-oils. 

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50 minutes ago, Danube Fiddler said:

While I can´t contribute to the chemical things, you just described - I assume, there could be two partially independent things : a) drying and b) loosing stickiness.     In my experience oil can dry quite a lot, but can stay sticky. My idea is, that the reason could be a certain critical component of the oil, which must get removed or destroyed. This component could be any substance soluble in fats and regularly existent in most kinds of plant-oils. 

Health food store sources of linseed oil, and artist supply sources can be very different things. We want them to dry,  and the "health food" industry doesn't.

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16 hours ago, David Burgess said:

Health food store sources of linseed oil, and artist supply sources can be very different things. We want them to dry,  and the "health food" industry doesn't.

My words

20 hours ago, Danube Fiddler said:

Thanks a lot for detailed informations ! 

Indeed I used  high-food-grade linseed oil, several brands. My idea was, that only such a ( bio-quality) foot-grade oil ( cold-pressed ) would represent a sufficient original oil- quality - so I would have total control over all processing things happening with this oil.  However now, after several new knowledge even about the bio-nutrition-industry I don´t trust any longer, that cold-pressed bio-linseed oil is really a natural oil without supplements. One has to know, that the nutrition-interests in oil-processing are completely contrary to the interests of the varnish- industry. The nutrition - industry wants to do all possible things to avoid oxidation/polymerisation - may be they add some substances to reduce these reactions but don´t declare it or use physical procedures with similar effects. Another thing could be special varíeties of linseed, optimized for the use as varnish but therefore unsuitable as food.

My idea of total control over all relevant steps of preparation of a total natural product seems to be very difficult, since I don´t know what 

a) the "health food" industry does/alterates/breeds  before ( normally at least the bio-industry is believed to do/alterate nearly nothing - but this belief is partially wrong )

b) the artist and varnish industry exactly does

The usility of linseed oil ( e.g. as filler) could highly depend on these questions, because all done alterations most probably would also touch the longtime behaviour of the grounds/varnishes.

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23 hours ago, Danube Fiddler said:

While I can´t contribute to the chemical things, you just described - I assume, there could be two partially independent things : a) drying and b) loosing stickiness.     In my experience oil can dry quite a lot, but can stay sticky. My idea is, that the reason could be a certain critical component of the oil, which must get removed or destroyed. This component could be any substance soluble in fats and regularly existent in most kinds of plant-oils. 

Oleic acid does not have conjugated double bonds (it hly one double bond, see picture from wikipedia). It will not contribute to the drying process as it can not crosslink. An oil high in this component (this could be envrionmentally influenced) would stay 'sticky', i.e. rich in unpolymerised components. I don't know what happens to oleic aicd over time, or whether it gets oxidised (more double bonds) when it is heated.

512px-Triglyceride_unsaturated_Structural_Formulae_V2.svg.png

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23 hours ago, David Burgess said:

Health food store sources of linseed oil, and artist supply sources can be very different things. We want them to dry,  and the "health food" industry doesn't.

I compared Kremer refined linseed oil with a food grade cold pressed oil from ebay  (https://www.ebay.co.uk/itm/Linseed-Oil-Pure-Food-Grade-50ml-1ltr-100-Cold-Pressed-Unrefined-Flax-FREE-P-P/202255083645?epid=5017655496&hash=item2f1757a87d:m:mBRyrd7gby4P0W5qFrK6y9Q&var=502218492010)

they both dry. The latter I washed with water for several weeks.

I will soon qualitatively compare drying times.

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1 hour ago, uguntde said:

I compared Kremer refined linseed oil with a food grade cold pressed oil from ebay  (https://www.ebay.co.uk/itm/Linseed-Oil-Pure-Food-Grade-50ml-1ltr-100-Cold-Pressed-Unrefined-Flax-FREE-P-P/202255083645?epid=5017655496&hash=item2f1757a87d:m:mBRyrd7gby4P0W5qFrK6y9Q&var=502218492010)

they both dry. The latter I washed with water for several weeks.

I will soon qualitatively compare drying times.

May I ask, if the cold pressed foot grade oil dried completely non-sticky on a glass surface ? 

2 hours ago, uguntde said:

Oleic acid does not have conjugated double bonds (it hly one double bond, see picture from wikipedia). It will not contribute to the drying process as it can not crosslink. An oil high in this component (this could be envrionmentally influenced) would stay 'sticky', i.e. rich in unpolymerised components. I don't know what happens to oleic aicd over time, or whether it gets oxidised (more double bonds) when it is heated.

512px-Triglyceride_unsaturated_Structural_Formulae_V2.svg.png

As I had read in Doerner or Wehlte, even Olive-oil ( with high content of oleic acid)  can dry under certain circumstances - it is normally called a not-drying oil. 

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