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Making Marciana Vanish

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...The only concern I had (and essentially the only thing that makes it much different from the Fulton/Hill recipe) is the addition of mastic. There was mention in past threads (ie - "its been rather quite around here") that with the addition of mastic, there is a possibility for the varnish to fail because it is essentially a megilp concoction. That is a serious threat to varnish, because it may not fail for 50 years, or more.

Is there really a problem with Mastic? Mastic shows up in a number of varnish recipes used experienced makers -- Darton's cold varnish, Marciana used by many here and I believe even one of Joe's varnishes has mastic in the mix. Can someone who knows about varnishes set the record straight?

Thanks Chris

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The problem with mastic is that it is expensive.

Yes it is expensive but is there a problem with using in varnish? I'm trying to sort out the fact from fiction with regards to mastic in violin varnish. On the one hand highly respected makers use it as part for their varnish, on the other hand some associate it with the potential negative affects of Melgip

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On the one hand highly respected makers use it as part for their varnish, on the other hand some associate it with the potential negative affects of Melgip

What make you think that megilp has mastic gum in it?

------------

I am bowled over that this was the first hit on Google when I typed 'megilp' and 'mastic':

http://www.nationalgallery.org.uk/technical-bulletin-vol-31/rachel_morrison2010

My avatar may give folks a clue...

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From what I remember Megilp uses raw mastic. Mastic in the Marciana recipe might be/ can be cooked and will not necessarily act in the same way...On the other hand the degree of degradation we see in the Reynolds paintings is quite nice over that time period for a violin and reminiscent of some Classic Old Venetian varnishes. If we can make a beautiful and protective ground on an instrument I personally prefer a varnish on top which might show the natural organic 'faults' of the great old Italians with time and use.

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Mastic in the Marciana recipe might be/ can be cooked and will not necessarily act in the same way...

*Based on Recipe 399, Marciana Manuscript

Materials:

2 parts purified linseed oil (sun-thickened if desired)

1 part Greek pitch (finely pulverized)

1 part mastic (finely pulverized)

Pour the linseed oil in a laboratory grade heat resistant vessel and bring it slowly to a boil. Slowly stir in the Greek pitch. When it has entirely dissolved, remove the container from the heat and allow it to reduce in temperature though not to cool (appx 80c). At this point stir in the mastic very slowly until it has dissolved. Return the container to the heat and cook to the desired consistency. Filter while hot through a fine mesh painters filter into a storage jar.

*Classic Italian Violin Varnish, Geary Baese

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I have found it difficult to find good 'scientific' info on mastic gum. MSDSs are missing lots of info ("not available").

Here is a paper on the composition of mastic oil. Limonene is relatively abundant. I presume these oils are volatilised during the varnish making - so what is the 'resin' left?

Mastic oil composition.pdf

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I have found it difficult to find good 'scientific' info on mastic gum. MSDSs are missing lots of info ("not available").

Here is a paper on the composition of mastic oil. Limonene is relatively abundant. I presume these oils are volatilised during the varnish making - so what is the 'resin' left?

Euphanes (masticadienonic acid,

isomasticadienonic acid),

oleanananes (oleanonic acid,

moronic acid),

dammaranes

" Mastic resin is derived from the genus Pistacia (Anacardiaceae family, four

Mediterranean species: P. atlantica, P. khinjuk, P. lentiscus and P. terebinthus) and has

been used as incense, as an adhesive and as varnish. Together with dammar resin and

sandarac, it is one of the most commonly encountered resins in the formulation of

varnishes for easel paintings. For this use, mastic was often applied in a mixture with

linseed oil, giving an oleoresins varnish which suffered from yellowing and craquelures.

Mastic resins have many components in common with dammar and elemi. The main

neutral triterpenoids are nor-a-amyrone, 28-norolean-17-en-3-one, hydroxydammarenone,

oleanonic aldehyde together with triterpenoid acids (oleanonic, moronic, isomasticadienonic

and masticadienonic) [92,114–122]. Unlike dammar resin, it does not contain

ursanes, and contains a relatively higher amount of oleanic species.

Moronic, isomasticadienonic and masticadienonic acids are considered as characteristic

and diagnostic molecules for assessing the presence of mastic resin in ancient samples

[2,88,94,123,124].

It is also well known that during ageing, new compounds are formed by oxidation reactions.

In fact, the presence of 20,24-epoxy-25-hydroxy-dammaren-3-one and 3-oxo-trisnor-

16 Organic Mass Spectrometry in Art and Archaeology

dammarano-20,24-lactone has been highlighted in several aged samples [125–127]. The first

compound is produced via the cyclization of the lateral chain of the hydroxydammarenone,

which then leads to the formation of a tetrahydrofuranic ring. The second is formed from

20,24-epoxy-25-hydroxy-dammarem-3-one by further oxidation reactions involving the formation

of a lactone derivative.

In archaeological findings the occurrence of a high abundance of 28-norolean-17-en-3-

one has been correlated to smouldering or burning processes undergone by Pistacia resins

[94,123,124]. Mastic also contains a polymeric fraction (15–20%) identified as cis-1,4-

poly-b-myrcene [128]."

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I am bowled over that this was the first hit on Google when I typed 'megilp' and 'mastic':

http://www.nationalgallery.org.uk/technical-bulletin-vol-31/rachel_morrison2010

interesting article! so is is possible the lead oxide in the megilp recipe is the culprit in the varnish failure in Reynold's pictures and not the mastic?

"A true gelled megilp is made by combining mastic varnish with a drying oil which has been prepared by heating with either litharge (lead oxide) or sugar of lead (lead acetate), and it may be that Reynolds made his own megilp medium in this way. Indeed, one of Reynolds’s notes specifically refers to a varnish made from mastic dissolved in oil with lead acetate…" http://www.nationalgallery.org.uk/technical-bulletin-vol-31/rachel_morrison2010

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I was surprised to read that sun thickened linseed/flax oil actually increases the drying time:

Sun-thickened Oil

Sun-thickened oil is prepared by naturally thickening linseed oil in sunlight. It is superior to stand oil (richer and more resilient). Sun-thickened oil is similar in consistency and workability to stand oil, however, sun-thickened dries somewhat faster. Stand and sun-thickened oils should be mixed as a painting medium before being used with oil paint.

..........

I figured being that raw, cold pressed oil absorbs lots of oxygen, after being left out in the sun the oil would have absorbed its fill of oxygen and then the drying process would be slowed down. However, this is apparently not the case, and the drying process is increased (I believe). I'm not exactly sure why, but I think I will try sun thickening some linseed oil and then maybe try incorporating it into a varnish recipe. This is the process to sun thicken oil, in case it's helpful for someone:

..........

Making homemade sun-thickened oil - The process of thickening oil is described in The Materials and Techniques of Painting, by Jonathan Stephenson. In the summer (or the tropics), pour about 1/2" - 1" thick linseed oil onto a flat, glass dish. The flat dish creates a large surface area for exposure to the sun and the air. Place the dish outside (on a ledge or roof) in an area that will be exposed to the maximum amount of sunlight. Thickening oil happens fastest in warm, sunny climates. Cover the dish with a slightly opened glass lid to allow for air flow. Stir the oil daily. After about a week or two, stir occasionally to prevent a skin from forming over the surface layer of the oil. Continue the process until the oil has thickened to a syrupy consistency. Impurities will settle to the bottom, so the oil on top can be poured off. Store in a glass jar with a lid.

..........

*http://homepages.ius.edu/dclem/ptgguide/ptggd2.htm#thickenedoil

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If you're using sketchy or very crude linseed oil it's also a good idea to 'wash' it. Simply add water to a jar with the oil and shake periodically. The water removes any water soluble materials present in the oil. Discard water the oil is clean when the water comes out clear and clean. Using distilled water may speed up this process.

'Oded

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I was surprised to read that sun thickened linseed/flax oil actually increases the drying time:

Sun-thickened Oil

Sun-thickened oil is prepared by naturally thickening linseed oil in sunlight. It is superior to stand oil (richer and more resilient). Sun-thickened oil is similar in consistency and workability to stand oil, however, sun-thickened dries somewhat faster. Stand and sun-thickened oils should be mixed as a painting medium before being used with oil paint.

..........

I figured being that raw, cold pressed oil absorbs lots of oxygen, after being left out in the sun the oil would have absorbed its fill of oxygen and then the drying process would be slowed down. However, this is apparently not the case, and the drying process is increased (I believe). I'm not exactly sure why, but I think I will try sun thickening some linseed oil and then maybe try incorporating it into a varnish recipe. This is the process to sun thicken oil, in case it's helpful for someone:

*http://homepages.ius.edu/dclem/ptgguide/ptggd2.htm#thickenedoil

Plus from what I have seen sunthickened oil not only "dries faster" but wrinlkles much less than raw oil or boiled oil (really boiled and the one I use for varnish) while drying. It probably not an issue for very thin layers but i might help

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Plus from what I have seen sunthickened oil not only "dries faster" but wrinlkles much less than raw oil or boiled oil (really boiled and the one I use for varnish) while drying. It probably not an issue for very thin layers but i might help

Robertdo, thanks for the info. By "wrinkle", do you mean it will get a sort of alligator skin type of cracking with age?

I tried sun thickening some flax oil, by putting a half gallon jar by a black light and an iguana light from the pet store for about a week. I doubt it did much, before I incorporated it into a batch of Marciana varnish. I think the old timers put it in a shallow lead tray and let it cook in the sun for a month or so.

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I would say more like "wavy", and it gets more and more with time.

On the picture the boiled oil is on the left side (the most wrinkled) while the right side shows some sunthickened oil. It may seem to get wavy too, but it's only because it was already so thick when I put it on the cover for UV exposure that I had to spread it a little bit with a rotation movement, so the pattern you see only comes from that. this part dried to the touch overnight while the boiled oil (on the left side) took 2 or 3 days to be dry to the touch and started to wrinkle.

post-29661-0-75079400-1322818974_thumb.jpg

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Over the last few weeks I have been making Marciana varnish a la Nertz.

During the resin cooking stage, I decided to follow the colour by placing a hot drop on a white paper. After adding the oil and mastic, I thought of comparing the new colour with the resin-only ones.

To my surprise, the hot drops developed a translucent halo which got bigger with time (reminded me of thin-layer chromatography).

The size of the halo becomes smaller as the varnish cooks, but is there even after hours at ~200 C.

Has anyone else noticed this phenomenon?

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Sure. Anything with oil in it will want to migrate out by capillary action. As you cook longer, the viscosity increases and the rate of migration decreases, but it's still there. Same reason oil varnish disappears into endgrain.

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If I were making this varnish I would be tempted to make a batch of 'cold processed' mastic and add it to the varnish after all the other ingredients have been cooked. I'm always dubious about cooking mastic, I don't think it cooks well.

has anyone tried this?

Oded

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The size of the halo becomes smaller as the varnish cooks, but is there even after hours at ~200 C.

After a day in the hot sun.

In #1 and 2, colophony, oil and mastic were cooked for 3.5h and 9h respectively, while in #3 and #4 for ~5h (all at ~200-210 C).

post-24474-0-29964600-1342382978_thumb.jpg

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