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Why not straight linseed oil with pigments for varnish?


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#1 GMM22

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Posted 08 January 2006 - 01:29 AM

One can read many (perhaps too many) violin varnish recipes that have linseed oil as their main ingredient, but they always contain at least one other constituent such as mastic, amber, copal, etc.

Just what is the actual purpose of these other ingredients? If linseed oil is a drying oil, then could one not use straight linseed oil with pigments added? If not, why?
If at first, the idea is not absurd, then there is no hope for it. AE

#2 fiddlecollector

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Posted 08 January 2006 - 06:07 AM

Resins add alot of properties to the oil ,such as varying degrees of hardness to the varnish film, brushing qualities,they can affect drying rate both positively and negatively. They increase the film thickness that can dry, they probably help to suspend pigment particles in the film. They can alter the optical effect of oil and pigments.They also increase durability. There are many other properties which iveprobably forgot to mention.

#3 Oded Kishony

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Posted 08 January 2006 - 10:22 AM

The possibilities are almost infinite. I've seen a cello 'varnished' with pure raw linseed oil. It wasn an awful mess. The instrument collected dirt, was sticky and sounded bad. Of course the maker assured the customer that she only need to wait and the crud on her 'cello would transform itself into glorious Cremonese varnish. Never happened, of course. Just like the idea suggsted to me once of painting your violin with olive oil-don't try this-olive oil is not a drying oil it NEVER dries.
By all means, if you have an idea try it-on a piece of scrap rib stock, if it looks promising then try it on a cheap factory instrument and if that works out then on your own fiddle. If you don't want to spend your life re-inventing the wheel, then read the literature on painting and varnishing. With the internet you have fantstic resources-use them.
Fiddlecollector covered the salient points regardign your question

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#4 Craig Tucker

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Posted 08 January 2006 - 10:34 AM

Oded,
you forgot to mention that olive oil is GREAT for a salad.


But even then it needs some balsamic vinegar....

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#5 Michael Richwine

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Posted 08 January 2006 - 01:37 PM

Linseed oil (raw or "boiled") never hardens at room temperature,
which is above its "glass transition point," even when fully
cured.



It attracts dust and dirt and incorporates it into the finish
throughout its life.



It continues to darken with age, eventually turning black.



Linseed oil gives  virtually no protection against moisture in
all its forms.



The added resins, when "cooked" with the oil,  give the finish
body and hardness, making it a varnish instead of just an oil.



This has been known for over 300 years.  I have dozens of old
formulas for varnishes dating back to the 1500's, all designed to
overcome the deficiencies of linseed oil alone as a finish.
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#6 troutabout

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Posted 08 January 2006 - 01:37 PM

A drop or two of olive oil keeps soups and rice from foaming over the top when it comes to a boil. It's slow evaporation also makes it ideal for luricating fine tuner threads and frogs.

#7 Craig Tucker

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Posted 08 January 2006 - 03:09 PM

"It's slow evaporation also makes it ideal for luricating fine tuner threads and frogs. '

Interesting. I've always used candle wax for this.

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#8 Oded Kishony

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Posted 08 January 2006 - 03:35 PM

I'm with you on that Craig, olive oil or other liquid oils can seep into the wood and potentially cause problems at a later point. However, I've been using bee's wax. I suspect that the difference between bee's wax and candle wax isn't worth arguing over.... The only oil that I know used as a varnish is tung oil. Tung oil has a significant flaw which is that it crincles (like on an old radio) as it dries. I believe that the commerical stuff you buy is treated in some way to prevent this.

The ingredients of the great Italian varnishes are known: pine pitch and oil (usually walnut but also linseed) The pine pitch may have also included pitch from Larch (venice turpentine ) or Fir pitch (Strassburg Turpentine) If I were a violinmaker that's where I would focus my attention.

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#9 Ken_N

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Posted 08 January 2006 - 08:44 PM

A couple of years ago I made a wooden flute.  Woodwind
instruments are quite a bit different than violins since they have
water going through them all the time, as vapor that condenses.
 I saw that quite a few makers used linseed oil, and a few of
them used vanilla or super glue as a catalyst to help it dry.
 I used the super glue with linseed oil, because I didn't want
to add a darker color.  I scraped off some of the hardened
finish that was left in a jar and soaked it in mineral spirits and
it doesn't dissolve, at least with spirits.  I don't know if
it dissolves in anything else. 

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#10 Michael Darnton

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Posted 08 January 2006 - 09:05 PM

Probably that's just the superglue.

I have a pan of oil in my shop. I started in 1995 with about 3mm of oil on the bottom, and kept it in my light box until it was hard enough to move around, then I turned it upside down so it would stay in the dark. Within about a year it dried to a very flexible, rubbery solid, very tough, but not very stiff (between jello and artgum eraser in hardness). It's stayed about the same all that time, but I understand that linseed oil goes through a lot of different phases over the centuries, sometimes even becoming more liquid. The drying curve is well understood among painting conservators.


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#11 GMM22

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Posted 08 January 2006 - 09:07 PM

Cyanoacrylate and linseed oil...? Hmm, that is certainly peculiar enough to want to try on some scrap.
If at first, the idea is not absurd, then there is no hope for it. AE

#12 Melvin Goldsmith

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Posted 08 January 2006 - 09:19 PM

Wonderful pic from Michael Darnton!..Thanks! ( don't you just want to touch!)
Linseed oil with pigments????....well..some people do use this in what is called a glazing method where they either sandwich thin coats of oil& pigments between layers of oil varnish or lay an oil and pigment coat over a varnish ground. Some Cremonese colour coats ( ie 1690's Strads) are very intense and thin..but I have not seen anything exciting via this method (so far)
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#13 Ken_N

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Posted 08 January 2006 - 09:38 PM

There was an article in Woodwind Quarterly called "Wood oil and
water" that can still be googled online.  It showed different
oils in their chemical chains.  Apparently the vanilla or
super glue have the right chemical formula to actually join with
the oil and oxidizes it.  I know it's not just super glue.
 There was only a dozen or so drops in about 4 oz of oil.
 It still won't stop water, just slows it down.  Like I
said woodwinds are different,  high humidity is their realm.
 Violins need to keep dry.

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#14 george behary

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Posted 09 January 2006 - 10:13 AM

I have done a lot of varnishing with TruOil (for gunstocks). I have added oil pigments and the finish is a tough but pliable transparent finish. Fun stuff to work with. It may not be for the purist, but a nice finish none the less.
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#15 David Burgess

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Posted 09 January 2006 - 04:22 PM

quote:


Originally posted by: Oded Kishony
The ingredients of the great Italian varnishes are known:
Oded K

????????????
Can you support this?
Last I heard, the Smithsonian Institution Conservation Analytical Labs didn't know what this stuff was, so I'm curious about your source.

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#16 Oded Kishony

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Posted 09 January 2006 - 05:45 PM

Ramond White and Louis Condax both identified the varnish as containing oleoresins and walnut oil. There have been some variations of ingredients identified such as mastic, sandarac, unidentified proteins, shellac etc. but my understanding is that 'pine pitch' and oil, linseed or walnut were the prime ingredients.

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#17 David Burgess

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Posted 10 January 2006 - 11:07 AM

It's been a while since I read Louis Condax's stuff. I think he was a brilliant man, but his research was limited to techniques of the time (40 years ago?).
As I recall, he primarily applied different solvents to varnish samples, observing what dissolved and leaked out, and physically probing what remained (usually a gel) to try to make an educated guess about what it might be. I think his conclusions included many assumptions, for example, "Protein is present, most likely glue".
Who knows? This type of observation may yield insights that more modern methods miss.

From a summary of a Raymond White paper by Robert Feller:

"Analyzing natural resins in the varnish layer of a painting is a demanding undertaking. Varnish additions may be present in the medium of the painting. The paint may also have a complex layer structure. The medium will have undergone centuries of thermodynamic and photolytic chemical change. The problems are accentuated by the increasing complexity of the mixture and by the general increase in the polarity of oxidation products, induced by lengthy periods of aging and exposure to the ambient environment. The inherent difficulties are compounded by the restriction on sample size.

One identifies organic materials within such samples by analyzing the material to establish the presence of a range of possible source-indicator compounds. Often, it is not possible to find indicators of such a specific nature to point to the precise origin of the material. Compounds may merely suggest a particular botanical or zoological genus, or even a family or sub-family. Such compounds are of use to the analyst as indicators, and may be either primary or secondary.

One may have to accept less specific results and have compounds that suggest certain plant compounds. How much of a resin sample needs to be present before one can detect it? How much shows age or very aged? This is a difficult challenge. It is essential to run analytical blanks along with the samples.

Feller noted some problems with these types of analysis. Shellac will not work in a gas chromatograph. One can find very little of primary indicators in copal varnishes because it is cooked during the preparation of the varnish. One must have absolutely clean working methods. If one handles the test tube improperly, it will pick up waxes and oils from your hand, and contaminate the analysis."


I think this gives a good picture of some of the challenges in identifying old varnish.
I'd like to believe it's linseed or walnut, pine or larch as much as the next guy, but there are pitfalls inherent in creating a hypothesis, then looking for information to support it.

Seems to me like we're still in the realm of educated guesses, and I'm not sure I've seen anything yet that I consider definitive. I'd be happy to update that opinion though if someone can give me a reason.

David

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#18 Craig Tucker

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Posted 10 January 2006 - 11:20 AM

...chuckle!

I can give you plenty of reasons.

(hey, wait a minute, does it have to be a valid reason?)

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#19 Oded Kishony

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Posted 10 January 2006 - 12:40 PM

David,

I would love to see someone re analyze (certifiable) samples using modern techniques and in fact I tried to get such an analysis done on a sample of Cremones varnish. After contacting an academic researcher who was qualified to do the research, I encountered a maze of issues about who controls the information, who takes the sample and and endless list of obstacles. In the end the project was abandoned due to these turf battles to the loss of all involved.
I'm not a researcher and rely on the research that's been done to help me decide what to do. Although what you present is a critique rather than a summary of Mr. White's work, I'm sure Mr Feller is right, there are many difficult obstacles to overcome but to the best of my knowledge the last word is that the ingridients known are more or less the ones I listed. Are you aware of any more recent research? (aside from Woodhouse /Barlow)
I believe the latest bit of information regarding varnish type materials that Strad used, was an analysis done of the 'inlay' of the decorated Strads, which turned out to be shellac. I thought this was particularly interesting.
In any case, I assume that we can agree that putting raw linseed oil on bare wood is >not< what the Cremonese did?

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#20 MANFIO

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Posted 10 January 2006 - 12:52 PM

Hi David, I'm a "ground maniac", so, if possible, I would like to know what are you using as a ground. Thank you in advance.




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