Varnish question.

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Toad
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Varnish question.

Messaggio da Toad » lunedì 21 marzo 2005, 19:42

Hello Claudio,

How are things in Italy? It is still very cold here in Göteborg. Somewhat strange for this time of the year.

Anyway, I was wondering if I could ask you if you have ever experinced varnish "bleeding" into your wood? I useally dry my varnish with a uv light, its broken now and I haven't fixed it. I varnish a back that other day it varnish sucked right through the back plate. I have never seen this before!!

I useally only use the clear varnish for the "ground/sealer" but as I have said I guess drying it in a UV box made a difference. Do you have any suggestions?

:?: :?: :?:

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Messaggio da claudio » lunedì 21 marzo 2005, 21:31

Toad, what kind of varnish are you using?

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Messaggio da Toad » lunedì 21 marzo 2005, 21:52

Claudio I use a colophonium/mastic varnish with linseed oil. I have use the same varnish, from the same batch, several times. The only thing that I have done differently this time is to dry the varnish without the use of a UV box.

Its based on a recipe in the Gary Bease book, one part cp, one part mastic, two parts linseed or walnut oil. It usueally works great but this time its reacting very strange.

Tomorrow I will try to post a picture so you can see what I mean.

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Messaggio da claudio » lunedì 21 marzo 2005, 22:38

Generally, I think is a good idea to use a good ground sealer for the oil varnishes, otherwise the slow drying varnish goes "into" the wood. To partially avoid this problem, you can use a whitegg or a hide glue ground.
In my opinion your varnish is particularly slow drying because the mastic: do you cook the mastic with the other ingredients? Also you need of a new UV light, absolutely, because your varnish won't dry in the cold weather of Sweden. Remember, the classic cremonese makers varnish their instruments from March to September, the sun (UV rays), are very important for us. To make the varnish slightly more siccative, cook the oil separately and make it dense like honey, then you can use it in a reduced quantity, 1/4 less. So if you use 1 part of resins, you should use 3/4 oil. Also, apply your varnish in thin layers. This is my experience with oil varnishes, of course. With the oil varnishes every time is an occasion to learn something new.
What colors are you using?

Claire
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Messaggio da Claire » mercoledì 23 marzo 2005, 17:06

Hur står det till?
If you have used the same batch of varnish before without difficulty, it seems unlikely that the formulation of the varnish is bad.

If I understand correctly, your problem is that the varnish sinks into the wood. That sounds like a problem with the sealer coat; it is not doing its job.

Besides the glair and glue grounds that Claudio mentioined, some makers here use a shellac ground. Also, a new trend among American makers is to use Imprimatura Dorata. Those who use it like it, but I do not know what is in it, and the commercial version is expensive. (Claudio, do you know what is in it? )

Baese himself recommends a sealer coat of clear varnish, but warns that it must not be applied too thickly or it will soak into the wood. Could this be what happened to you? Baese says the sealer coat must dry thoroughly before the other coats are applied. If you were not able to use sun or UV lights, perhaps the sealer coat did not dry adequately.

I hope this helps.
-Claire

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Messaggio da Toad » mercoledì 23 marzo 2005, 18:59

Tack alldeles utmärkt. Hur står det till själv? Talar ni svenska?

Thanks for the advice guys. I have used the varnish before, serveral times actually, with great results. The only problem this time is the that my inital coat didn't dry, well, it just sucked right into the wood. I had thought that there might be a problem with drying so I applied it thinnly to no avail. I haven't put any addional coats on yet.

I don't use a sealer coat per say, only as you mentioned, well Bease mentioned it, a layer or two of clear varnish.

Anyway, Claudio your right about oil varnihs being a learning experince.

For the colouring I use pigment lakes, again thanks to Bease, madder, weld, cocchineal, etc...stepped wtih alum, pot ash. I have amazing colour from rathany root that I am itching to use. Anyway, I a familar with the process it's just that I have never seen varnish suck into wood like that before.

A friend of mine in Germany says that some of the Magister stuff, along with another brand of "sealers", "grounds" and whatnot were based on something rather carcinogenic (and that he couldn't pronaounce in english.) The later from Italy was actualy, so he told me, illegal in Germany.

Regardless of what it is I don't like working with chemicals if I don't know what it is. I certainly wouldn't use it on a violin which is stuck under someones chin for a few hours each day. Just my two cents.

I think I will try some egg white on the next violin :)

What are you useing for varnish Claire?

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Messaggio da Claire » mercoledì 23 marzo 2005, 19:29

Böter , tack själv. Nej -- men jeg indtale noget Dansk.

In the past I used a spirit varnish. I have just begun using an oil varnish and just finished one using amber varnish. I like it, but I used Rubio mineral ground applied with waterglass, which Claudio says was a mistake.

I am preparing a batch of mastic and linseed oil varnish right now, and I plan to use it on my next instrument with glair as a sealer.

I always fight my varnish, and am still seeking the holy Grail...

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Messaggio da Toad » mercoledì 23 marzo 2005, 19:43

(with a great danish accent) För Helvete!

When I was in school we used a spirit varnish, fine enough I guess. The problme was that everyone treated the wood with dicromite first. The varnish itslef was also difficult to apply and wasn't, well, over transparent for one.

The notion of polishing out 24 coats of spirit varnish was lost very quickly with me :D

They had the Bease book at school, I copied it and began. No fires to date but I did manage to melt the heat gun. I have heard that some people have put abit of pumice in with the first coat of Bease varnish for the "ground" with good result. I haven't tried it yet though.

I heard the same thing about waterglass. I think it was Jefery Holmes on Maestronet.

I tired the Bease Mastic linseed oil varnish as well but never mangaed to get it to work. I suspect I just need to cook it alittle longer though. The amber varnish and the cp/mastic exceeded m expetactions though so I haven't really pushed on the mastic/lino one yet. I really liked the colour of the amber varnish but found it to hard. Used it up though.

Are you making you own pigments Claire? The bease recipe is time consumming but easy to make and quite interesting. the ruelsts as quite exceptatble as well.

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Messaggio da Toad » martedì 12 aprile 2005, 0:18

Hey I thought that I would let you guys know that my varnish finally dried! We got some sun here and thanks to the living room window the prblem was solved. :)

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Messaggio da claudio » martedì 12 aprile 2005, 10:52

Nice news Toad! :D
This confirms that the sun is very important for our varnishes, although seem that the oil varnishes give us a different result compared to the classic instruments.

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Messaggio da Toad » mercoledì 13 aprile 2005, 22:54

Claudio do you think that varnish should be think or thin? I worked on a Montagnana cello the other day and where the varnsih was unpolisehed(or less so) it was very, very, thick.

I was tought that thin is better, acustically. Anyway, do you have any thoughts about this?

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Messaggio da claudio » mercoledì 13 aprile 2005, 23:08

I used thick and thin varnishes: if the varnish is good, the instrument won't suffer for it. Anyway my advice is to apply a varnish coat between 0.1 and 0.2mm. In the year 1987, I saw an interesting Strad's cello in the Cremona's big show (stradivarian anniversary), it had a lot of unpolished varnish!

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