Linseed Oil Drying

[HongDa]

Sir Hilary,

I use a staining process first with different things--different for the spruce and maple.Then have it sealed in with my shellac varnish--several coats.Followed by the oil varnish.

[AMORI]

As far as I know, mastic occurs only on the island of Chios, so I imagine that the stuff directly from the source must be as good as it gets http://www.mastic.gr/default.html?lang=en-gb..

I have been away for a week and in that time the violin with which I had all the (Darnton) drying problems has dried well. That is, after finally using el-cheapo raw linseed oil. The previous mix with artists linseed never did dry.

[joerobson]

I think that Michael Darton is a better source for information on this mastic varnish as the process is quite different than the ones that I use.

[MANFIO]

Hi Joerobson! I've got the bait! What's your process?

[Michael Darnton]

He makes more traditional varnishes:

http://www.violinvarnish.com/

[HongDa]

Yap,

concerning oxygen. Turpentine absorbs oxygen during the evaporation process, so this is what helps the linseed oil dry and where it gets it's source of oxygen.

Well I have about exhausted my experiments now.

I have tried both sunbleached oil and coldpressed oil with amounts of 25, 35, 45, an 50 % to the mastic.

Both these oils dry on their own but when mixed with the mastic at any percent they end up just the same no matter the amount of oil---still tacky to a firm fingertip pressing.

I also managed to get some copal and also some sandarac to mix with the varnish but it's very tricky (at least without cooking), and it doesn't improve the problem any.

At this stage I guess it's back to my old boring seedlac varnish.

I have one more test strip with 60% linseed oil but I doubt that will make any difference.

The biggest bummer is that I have 2 violins hanging with beautiful red varnish made with pernambuco pigment as the base color---several people have their eyes on these instruments. I don't have the heart to strip them down so will just let them hang. If it takes a few years for them to dry more then that's fine with me.

Have you tried the damar varnish?

[fiddlecollector]

Funny thing is i have always had similar problems when using dammar but never with Mastic!Must be a humidity combined with heat problem. Its very humid here but not very hot.

[fiddlecollector]

```Yap,

concerning oxygen. Turpentine absorbs oxygen during the evaporation process, so this is what helps the linseed oil dry and where it gets it's source of oxygen.```

Not correct, it may help but oil absorbs oxygen on drying by itself.

[Michael Darnton]

My first varnish was dammar. I cooked it until it was about half-reduced in volume (basically you're burning out the waxes), then added pre-cooked oil (light honey consistency) and cooked for another couple of hours. That varnish is slow drying at the start, but after it's been made for a year or so, it's much quicker. It worked fine, though at the time I didn't feel it was transparent enough, and was too durable for what I wanted. Now things I did with it have cleared up quite a bit, and it looks fine. I still have a batch from 1991, about a pint of it, and I bet it would dry quickly now. :-) I think the exact recipe is in one of the GAL publications somewhere.

[fiddlecollector]

Thanks , i might try that sometime, so you have to use it in a vintage state??

I once bought a bottle of Windsor and Newton picture varnish (dammar and turps) and it had the same problem, remained tacky for ever.(so i never used it for anything).

[Michael Darnton]

But the W&N picture varnish, being just dammar alone, is vulnerable to the turpentine going bad, for instance, and also alone, like many resins, it doesn't let go of solvents well and is vulnerable to humidity.

My recipe will work fine fresh, but it takes a couple of days to dry. After it's aged, it will dry overnight. That's a common thing for any oil varnish, not just mine.

[TimRobinson]

Well, it has been about a week and these are my impressions of how the different mixes dried. I put one drop of each of the oils with two drops of mastic/turps mixture and spread it on some maple prepared with vernice bianca. I put the wood in a light place, but under a translucent fibreglass panel so I guess much of the UV was filtered out. The results in order of stickiness (finger pressure for ten seconds) more to less:

Boiled linseed oil

Flaxseed oil, extra virgin food grade

20 year old virgin linseed oil

Refined linseed oil, artist grade

I will now make up enough with the refined oil to use on a violin and give it a go. I reaslise the varnish is not meant to be hard, but it seems to me that the refined oil varnish will withstand handling and use without being sticky like the others.

Rgards,

Tim

[HongDa]

FC, I'm still not convinced it's a humidity problem because even when I take an instruemnt right out of the box and give it a firm pressing I still get a print.

[Michael Darnton]

How is it after you let it cool off? Mastic has a rather low melting temperature, especially initially, plus it's very slow to let go of solvent--even six months later it's still shrinking.

[HongDa]

it seems to print easier after hanging out of the cabinet.That's where I don't know if the humidity may be having an effect.

I was just talking to a friend who also tried this varnish in a humid place. After a month now he says his is dry.In the beginning it was also sticky.

The difference between his varnish and mine is he let his set 2 months before getting time to try it.

He also suggested trying less then 20 percent.I havn't gone it that direction yet so may as well see what happens with only 15% oil.

[yapkv]

Hi Hongda,

I have been trying out these varnish for the past few days:

1. mastic dissolved in Euc-oil and linseed oil

2. mastic in turp and linseed oil

3. mastic in turp with copal varnish and linseed oil

4. a old batch of damar varnish i made last year as per MD recipe

i left the test strip under the sun and the only one that dried well was the dammar varnish. the mastic versions were all tacky. I guess it may due to the quality of the mastic I used, the temperature / humidity... I must say the drying time for the damar varnish has improved a lot!! i can actually press it as hard as i could without feeling tacky.

I wonder if it was due to where the resin is produced. Damar can be found locally here. mastic is mostly produced in Mediterranian (?). Since resin is secreted by the plants to protect them from infection due to cuts, the constituents of the resin may have properties that allows the resin to be solidified efficiently in their own environment. again i am just guessing....

[Claire Curtis]

I used an old broken kitchen knife to mix my mastic and turpentine (it was too much of a sticky mass for shaking to be sufficient). The knife is now coated with a hard, dry, thick, and extremely shiny coating.

From this I would conclude either:

1. The mastic alone drieds fine, but is not an attractive varnish. This suggests that the excessive stickiness some folks are experiencing probably results from the oil used.

or 2. perhaps the steel blade (carbon steel) acted as a catalyst and provided some sort of drying agent -- you chemists out there can tell me if this is likely.

I haven't yet used the mastic with oil (ie the varnish).

--Claire

[HongDa]

Quote:

---

. This suggests that the excessive stickiness some folks are experiencing probably results from the oil used.

or 2. ....

---

Claire, between the 3 of us on this post having problems---it sounds like we have used every type of linseed oil there is. We each also have different sources of mastic.

Are you suggesting maybe the particular bottle of oil itself is bad for some reason?

[Claire Curtis]

Possibly -- different linseed oils were listed, but there are so many other factors. Think of how different oilve oil is, and how even if you have two bottles from the same source, one will taste differently from the other if it has been kept on the stove instead of in the fridge. It seems to me quite possible that 'artist grade' linseed oil that has sat in a 75°F warehouse for months might behave somewhat differently from linseed oil that has been kept in freezing termperatures. (Artist grade linseed oil from some manufacturers is dated, which suggests that some change can occur over time).

I'm not saying that's the problem. I just had not expected the dissolved mastic to form a hard coat on the knife; I thought it would remain sticky. If mastic alone can dry (keeping in mind that this is a sample size of one), then it seems that lack of oil doesn't prevent drying. But -- here's another factor -- my mastic was quite old, and took a couple of weeks to dissolve. Perhaps the fresher mastic dissolves easier, but doesn't dry as well.

As you can see, I'm just throwing out possibilities for consideration.

I'm still intrigued by the sucond suggestion, that iron may be a factor. Many old manuscripts specify the material used for containers or utensils, so there is a certain plausibility to the idea. I'm hoping someone will chime in on this.

Another possibility is that there may be a difference in the turpentine used. Since it is considered a solvent, the manufacture of turpentine tends to be less rigorously controlled than that of "ingredients". It's made from pine, but the species of pine may matter, for instance, which may change seasonally or between batches from the same manufacturer.

Perhaps what we need here is for the people who have been successful to give details on how they made the varnish. Source and age of mastic, turpentine, and oil; temperatures during mixing, nature of utensils, etc.

One would think that in a varnish made with only three ingredients, and no cooking variables, we could obtain better consistency!

[TimRobinson]

Claire, your suggestion about the turps being the possible source of the problem was in my mind as well. I used fresh Chios mastic (I assume what they sent me was new) but the turps was not from an artist supplies place, it was from a paint shop (Diggers brand - how Oz can you get). As it is made in Australia the question in my mind is what is it actually made from? It evaporates away, but I wonder if what is left behind is the, or part of, the problem.

Tim

[HongDa]

Quote:

---

Perhaps what we need here is for the people who have been successful to give details on how they made the varnish. Source and age of mastic, turpentine, and oil; temperatures during mixing, nature of utensils, etc.

One would think that in a varnish made with only three ingredients, and no cooking variables, we could obtain better consistency!

---

Thanks for the ideas Claire.

It's a very nice varnish and so simple to make. It (and Michael) absolutely deserve having the problems worked out that a small percentage of people are having with it like myself, so that years later people can say , "here's a very simple varnish that works all of the time. Anyone can make it". This is the only place that the problems are likely to be worked out also.

At the moment I would recommend it to people but with the warning they stand a small chance it may not work. It would be nice not to have to add such a warning.

I think a seperate post for those who have done it succesfully would be the thing to do.

If you look through previous posts you can get bits and pieces of success information, but at this stage with all the different post it's scattered all over and hard to put together.

[Claire Curtis]

Hi Tim -

I just plugged turpentine into a search engine, and found there is a species of tree in Australia called the turpentine, Syncarpia glomulifera. Since that's not even a pine, it might really confuse matters if there were a solvent derived from it. Does your Diggers label say anything about what tree it's made from?

The UN Food and Agriculture webpage --

http://www.fao.org/docrep/V5350E/V5350e10.htm

-- distinguishes "gum naval" turpentine, which is derived directly from trees tapped for that purpose, and "sulphate naval" turpentine which seems to be from processed slash. There's interesting stuff on that page about what pine species are used where. The only species with USA as a source is Englemann; South Africa apparantly uses both Englemann and Caribbean Pine. Australia is not listed, but Merkus pine is listed with Indonesia and Thailand as source countries. China seems to be the biggest producer worldwide, and uses Masson pine.

Don't know what all this means, but it's interesting....

-Claire

[Claire Curtis]

Just to confuse matters more, http://dict.die.net/turpentine/ says turpentine is "primarily the exudation of the terebinth, or turpentine, tree (Pistacia Terebinthus), a native of the Mediterranean region." and later defines Turpentine tree as "the terebinth tree, the original source of turpentine."

hmmmm...

OK, enough playing, back to work. Gotta finish an emergency repair for a student who has a recital tomorrow. Her sister stepped on her fiddle....

[HongDa]

Interesting.

I have been using Windsor Newton English distilled turpentine. I can't find specifics on it but they do mention on their site that it is the only artists grade turpentine strong enough to easily disolve damar.

I had this suspicion that maybe turpentine disolves something undesirable in the mastic that alcohol doesn't.

So, perhaps different turpentines have different disolving powers and the one I am using is too strong?.

I have a few grams of mastic that I disolved in alcohol an let evaporate to test my suspisions. I'll now devide that in half and use a different turpentine in one half and the same turpentine in the other.

[TimRobinson]

Claire,

I have the native turpentines growing in the nature reserve behind our house. I doubt that species are the source of the product I bought, but I could be wrong as native hardwoods are heavily logged here. By the same token, we have very large plantations of radiata pine which grow faster than the natives - I have no idea if they may be used to make the gum turps. I'll contact the manufacturer and find out what they use.

Tim