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Damar + linseed oil Ground/Clear Varnish


David A.T.
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Triing to make a linseed oil based ground I did the following.

I tried some varnish samples with cold Damar and linseed oil (tried cooked and refined) ratio 1 resin 1 oil. Not all the Damar dissolved. But I tried the liquid part on a ceramic plate. Both are not working. After few weeks the samples on a plate are still sticky. I think wathever the concentration  it will not work because even a sample with coocked linsed oil alone is not dried.  Which means reaction with minerals from siccativ ( or wood itself)  and coocking is necessary ( i guess this comment is trivial/obvious for most serious readers of the forum).

Then I tried to cook in a deep frier. Temperature is going up to 190C/374F and i can control the coocking time.

After 3 hours ,

All the Damar dissolved quickly in the oil. And bubles going up and down trend to reduce in density

1. Then i just ask. How long do you recommend to cook ?  Before I stop and make a New trial on a plate.

2. I wonder also if it makes sense without minerals additives. Is there a chance that this will work as 2a.Ground? 2b. Clear varnish? 2c. Both?

 

Maybe 190C/374F is not enough also. I see lot of receipts with higher temperature but I don t have safe equipement for that.

 

If some have interest in these tests let me know.

 

16270424462426362673462862443975.jpg

 

Before coocking it was like that:

16270428272551786174654716888160.jpg

Edited by David A.T.
Last picture is before coocking. It might be confusing
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  • David A.T. changed the title to Damar + linseed oil Ground/Clear Varnish
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If that is all I had to work with I would try 1/3 dammar, 1/3 linseed oil and 1/3 spirits of turpentine.

What you could try is one teaspoon of what you have there in the jar and add one teaspoon of spirits of turpentine for starters -  don't be in a hurry, let them blend together for 3 or 4 days.

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Dammar varnishes are more typically made by dissolving in turpentine or alcohol. Anything that does not dissolve is thrown away. Dammar in turpentine can make a very clear, high quality varnish that dries hard.

You might be able to get it to combine with linseed oil by by first dissolving it in turpentine in a ratio of 4 turpentine to 1 dammar by weight. Discard whatever has not dissolved. Then add 1 part linseed oil.

Like all anecdotal recipes, your mileage may vary. Also, turpentine is a bit toxic and many find its odor to be obnoxious.

You might want to try a resin that is more compatible with linseed oil.

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Thank you for the tips. So far I jusk cooked them together and got this.

For sure it can't be used as this. Too thick.

 

I will let few days to see if the drop trials on white ceramic becomes hard. In the same time I will dilute a sample with turppentine. I will start with 1/3 turpentine and see. 

 

 

16270627259043721417852906324818.jpg

16270627451552260398355239119239.jpg

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Diluted with 1/3 turpentine.

It diluted quickly as the oil+resin was still warm.

I add one drop in the middle on the test plate.

Left :

1/2 fine linseed oil + 1/2Dammar . 6 hour backed at 190C

Right :

Same with coocked linseed oil from the shop.

Middle :

2/3 Right sample + 1/3 turpentine.

I expect/hope it becomes hard after 1 week.

I also did a drop on mapple from the middle sample to see if it harden differently as on ceramic.

 

 

 

 

16270631788888945915102219133547.jpg

16270634185995016618592698543669.jpg

16270637999587172535323830364951.jpg

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5 hours ago, David A.T. said:

After few weeks the samples on a plate are still sticky. I think wathever the concentration  it will not work because even a sample with coocked linsed oil alone is not dried.

if linseed oil alone (cooked but also raw) does not dry out and remains sticky in a test on glass, I think you have a problem. In fact, the drying property of the oil is the first thing to check to make sure that your varnish will works

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23 minutes ago, uncle duke said:

one U.S. teaspoon = cuiller a cafe * just so you know.  

:DThank you. True. I made much more, and for sure too much. But if it fails I will use it for my garden. Outdoor wood always require some protections.

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40 minutes ago, Davide Sora said:

if linseed oil alone (cooked but also raw) does not dry out and remains sticky in a test on glass, I think you have a problem. In fact, the drying property of the oil is the first thing to check to make sure that your varnish will works

It might be a good reason. I am not sure about the expected result. It seems I still can print my finger on the sample after few secs pressing.

I bought my oil by 2 good dealers but maybe not good enough for violin varnish. I did so many trials that i will run out of stock soon.

I don t know how to ask you. But let' s try .

Maybe can you share a good Italian (:rolleyes: or not) linseed oil dealer?

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3 hours ago, David A.T. said:

 

Thank you very much for sharing :D. I will order a sample and make a try to see the difference.

Note that some receips recommand boiled oil, but some recommand raw oil. This one is not boiled.

Both can be fine, if the quality of the oil is good, but if you want to be aware of the processes that the oil has undergone and the additives that have been added (drying metals) the only way is to start with the raw oil and do all the necessary steps yourself. It can also have an influence on the final viscosity of the varnish, as the boiled oil will become more viscous for the same cooking time (because it will be re-cooked to combine with resins). So the cooking times will have to be set up differently depending on the oil you use and the result you want to obtain, especially if you don't like using large amounts of solvent / thinner.

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28 minutes ago, Davide Sora said:

Thank you Davide.

In the Damar section he recommends to cook the resin till it becomes dark without giving the reason why it requires to go  so far . I had no trouble at all to dissolve the Damar with oil while it was orange. Maybe I will have more trouble with the driing time.

After day1, the drop are not dry yet.

 

 

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16 minutes ago, David A.T. said:

After day1, the drop are not dry yet.

Drying time highly depends on the film thickness, and the level of UV exposure.

An example: After one day of drying under UV light, a fairly thick film of linseed oil was still pretty soft. After three weeks under the same level of UV light, it was starting to approach brittleness.

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4 hours ago, David A.T. said:

Thank you Davide.

In the Damar section he recommends to cook the resin till it becomes dark without giving the reason why it requires to go  so far . I had no trouble at all to dissolve the Damar with oil while it was orange. Maybe I will have more trouble with the driing time.

After day1, the drop are not dry yet.

 

 

Dammar has quite a bit of wax and perhaps also some soft components in it that need to be burned out. Thus my recommendation for boiling it to half the amount you start with.

You cannot make a proper oil varnish without  cooking the dammar and oil together at a high heat to the spider web stage. Oil and resin mixed without cooking do not make a real oil varnish where the oil and resin are permanently, chemically joined. Only mastic permits that, of all of the resins, AFAIK.

Most real oil varnishes dry faster as they age in the bottle. Six months is a good start.

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8 hours ago, Michael Darnton said:

Dammar has quite a bit of wax and perhaps also some soft components in it that need to be burned out. Thus my recommendation for boiling it to half the amount you start with.

You cannot make a proper oil varnish without  cooking the dammar and oil together at a high heat to the spider web stage. Oil and resin mixed without cooking do not make a real oil varnish where the oil and resin are permanently, chemically joined. Only mastic permits that, of all of the resins, AFAIK.

Most real oil varnishes dry faster as they age in the bottle. Six months is a good start.

Thank you for your article( great job !) and contribution in this post.

in the Tolbecque Book, there are  receipts with Damar and Mastic. 2 parts Mastic / 1 part Dammar./1 to 2part oil They are prepared at room temperature (or water bath, but not higher) and then diluted with Turpentine.  Due to Mastic cost I started only with Dammar - which is really a cheap resin and recommanded by the shop as similar to Mastic. But I probably miss the Mastic properties in my mixture.

The Hammerl book also recommand to cook at high temperature the resin. 

It could be an esay test to take one part of my mixture Dammar/oil/Turpentine and dissovle some Mastic in it.

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