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About cooking varnish

I have received some e-mails about my varnish cooking and haven't had time to answer. These links describes the cooking with an image album from last summer''s batch

It starts with reducing Colophony, cooking it slowly (150 - 180  C) for 4,5 h to 10 h.

Cooking varnish is SUPER SIMPLE, there is nothing strange about it and it involves no difficult tasks. The only part that should be carefully done is when adding turpentine at the last stage.

Don't pour cold turpentine into hot varnish! Cool down  the varnish to 100 - 120 C and warm up turpentine to simmer before slowly pouring it into the varnish (while stirring)

http://www.thestradsound.com/varnish/varnish-recipe

https://photos.app.goo.gl/eTnryGmEom3565kx1  

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17 hours ago, Szymon said:

Peter, do you add siccatives to your oil varnish? If so, what amount?

No I don't add siccatives. Boiling cold pressed linseed oil 4-5 hours at ~95 C, makes the varnish dry fast, but UV is needed.

BoilingLinseed.thumb.jpg.9f78213dedc36bb5e417a32ad8f2b292.jpg

 

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Still no workshop time, but always time for observing.

The four "Soil copies" are now back in summer mode. I like the winter mode too, bright and on the edge, but they are at their best in this condition.

We have a Swedish term for how to describe a violin with this property/quality - Violinen har märg 

 

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On February 2, 30 Heisei at 7:50 PM, Peter K-G said:

No I don't add siccatives. Boiling cold pressed linseed oil 4-5 hours at ~95 C, makes the varnish dry fast, but UV is needed.

BoilingLinseed.thumb.jpg.9f78213dedc36bb5e417a32ad8f2b292.jpg

 

Your pot and equipment looks so clean!

 

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:)

It was brand new at the time the photo was taken. Nevertheless I do keep my varnish cooking quite clean. 

Later this summer it's time for more varnish cooking

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I have stopped using lime in varnish cooking a couple of years ago. It makes it too hard with the colophony I use and it is more durable to moisture (sweat) without the lime.

There has been a lot of discussions about this and my conclution is that some rosins need to be limed because of its acidity level.

 

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2 hours ago, Peter K-G said:

Of course i couldn't wait to test it :) Three layers of varnish, no ground (backside of the piece for reference)

WP_20180617_19_46_58_Rich.thumb.jpg.ebc7e196c003ba13105e7b4c72d2d8a7.jpg

WP_20180617_19_34_42_Rich.thumb.jpg.a9c240c7ed427d3b052a6be0f5c16191.jpg

WP_20180617_19_47_49_Rich.thumb.jpg.74fe572f9648afec16f29bc8e8aede55.jpg

WP_20180617_19_49_23_Rich.thumb.jpg.40f64219606a4c8e2bff1dde5038d444.jpg

WP_20180617_19_48_44_Rich.thumb.jpg.e7916cfad9f1cfb00bf2b190c6049760.jpg

 

Are those coats applied relatively thick or thin my friend? Thanks!

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6 minutes ago, Nick Allen said:

Are those coats applied relatively thick or thin my friend? Thanks!

Three thin layers, deluted with ~40% turpentine

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2 minutes ago, Peter K-G said:

Three thin layers, deluted with ~40% turpentine

Wow. That's impressive color intensity for only three thin dilute layers. 

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Thanks!

I think it's a matter of what type of rosin you start with and how much it should be reduced by cooking it, to get really dark varnish. (ref. Hargrave cooking long and slow topics)

It is also important to not burn it (red color is lost), so I constantly stir it during 9-10 hours, every 15-30 min or so. The temperature also needs to rise gradually to get the same viscosity. (melting point is rising when it is reduced)

At the end of cooking I always wonder if I have overdone it, because it is pretty much black. I didn't take a photo of just colophony, this is a dip into the varnish when it is ready cooked together with linseed oil, mastic and turp:

WP_20180616_22_40_58_Rich.thumb.jpg.08ce91c392c1bc2036c8a3513867573b.jpg

 

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11 hours ago, Szymon said:

Hello Friends, I have not been to the forum for a long time. This is my yesterday's varnishing

 

Nice! 

Thanks for sharing, I have yet to make some own pigments as you posted earlier in this thread.

I'm going to strip varnish of an earlier violin I made and re-varnish it with this new batch.

 

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Yours results are very inspirational! My short  movie - the are three layers of Oldwood varnish with my alizarin in a weight ratio of 1 part pigment for 4 parts of varnish. The results - a very thin coating, a yellow to amber deep color. But next time I will preper my own varnish according your recipe.

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We have an amazing summer this year with weeks of sunny and warm days (by our standard 27 - 32C)

So what else is there to do than test ground&varnish B)

Quark&Lime ground after 7 days in direct sunlight really nailed the old wood look, the reaction was amazing I haven't come even close to this with UV tubes tanning. The same ground and one really thin layer of varnish on a tanned and a white piece of wood:

TannedBeforeQuarkLimeGround1.thumb.jpg.3919bcfea21aed2928e33aa5a56d6e5b.jpg

TannedBeforeQuarkLimeGround2.thumb.jpg.e1136878f9d4db0d3fc11292adfd37fc.jpg

One more thin layer of varnish

TannedBeforeQuarkLimeGround3.thumb.jpg.35b8d7322842337f3f4a6582bd1ff27c.jpg

 

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