Weak Rosin/Linseed oil varnish. J.Michelman recipe failed trial.


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Chemist here:  The rosinate is a salt.  

The purpose of cooking the oil and rosin is to achieve a chemical reaction between the oil and resin.  A polymerization reaction.  Cooking at 120 C (as Jackson reports) is not a very high temperature to achieve the polymerization, but I cannot say it is impossible if it is maintained for a long enough time.

The traditional Michelman varnish is a complete failure as Don Noon states.  John Masters lives in Cincinnati and has seen the old instruments with this varnish, and has reported on it on Maestronet.

Good luck with this topic

Mike D

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1 hour ago, Mike_Danielson said:

The rosinate is a salt

I stand corrected. Thank you. Worth noting that the solubility of salts varies widely, and that rosinate is entirely insoluble in water. Edit: not all rosinates are insoluble in water. Calcium rosinate is partly water soluble and should be avoided, for example.

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Thanks for your video. Your recipe resist to the main player environnemental factors. 

My varnish looks much more soft (2 weeks aged though) and much less colored despite I used a lot of madder. JM described in his book a red color varnish without use of the iron.

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I think about an other différence.

My varnish is still 'usable'. I dont need to prepare a new one while you say it require fresh one for each coat.16147741505204582427633303793931.thumb.jpg.d74af8b931aa87213c300b97e20f3a3e.jpg

It is still very fluide. I remenber I added few drops of Aspic before applying it.

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3 hours ago, David A.T. said:

I think about an other différence.

My varnish is still 'usable'. I dont need to prepare a new one while you say it require fresh one for each coat.16147741505204582427633303793931.thumb.jpg.d74af8b931aa87213c300b97e20f3a3e.jpg

It is still very fluide. I remenber I added few drops of Aspic before applying it.

Forgive my confusion, but by your own admission throughout this topic, your varnish does not work in any respect. it doesn't dry and it lacks intensity. Whether or not it remains fluid is essentially irrelevant if you use the original Michelman cold mix technique. Michelman himself makes it clear repeatedly that his varnishes when properly formulated do gel and must be prepared fresh for each coat. That yours has not exhibited this behaviour should be taken as a mark of failure. 

I assure you that using my technique will, if you follow it to the letter, give you varnishes you can count on. If you cannot prepare these carefully and to a high standard of accuracy, rosinate oil varnishes of my formulation can be bought. 

Please understand that I am happy that others are taking advantage of Joseph Michelman's excellent research - I have long been dismayed by the vitriol with which his work is denigrated by people who simply couldn't make it work. I want to be of help to anyone who is curious about these finishes, hence why I published my technique and continue to discuss it with any who wish. 

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I would be happy to restart the process and post here. But my instrument is just finished. As  fresh varnish is required just before application I wonder if it makes sense to prepare it now. I need several month to make an instrument

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24 minutes ago, David A.T. said:

I would be happy to restart the process and post here. But my instrument is just finished. As  fresh varnish is required just before application I wonder if it makes sense to prepare it now. I need several month to make an instrument

For your currently finished instrument, I recommend finding a successful varnish that you can live with and apply it. Then, if you are still interested in rosinates, prepare some according to my article and cook them into oil as I described and use that on your next one. Best of luck and keep us posted.

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Posted (edited)

I just received a red italian oil varnish from Joha/Hammerl.

I tried to mix a bit with a part of my varnish. Both are oil based and look like to have same viscosity.

When mixed it turned to a paste. Probably it is a proof that I had too many minerals in my varnish.

David.

Edited by David A.T.
I Removed links (not related to the comments)
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1 hour ago, David A.T. said:

I just received a red italian oil varnish from Joha/Hammerl.

I tried to mix a bit with a part of my varnish. Both are oil based and look like to have same viscosity.

When mixed it turned to a paste. Probably it is a proof that I had too many minerals in my varnish.

David

Cello #1 : https://youtu.be/Ik1T6smpTFc
Cello #2 : https://youtu.be/rBX_9LnsoQM

Cello #3 : in progress

Since your question is about varnish, and since the videos reveal little useful information about your varnishing process, it's difficult to provide useful commentary.

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58 minutes ago, joerobson said:

Well I knew I had these in the archives somewhere...

Varnish and varnishing by Michelman

michaelman tops 1(3).jpg

michaelman backs 1.jpg

michaelman signiture.jpg

They look pretty damn good, don't you think? Assessed for what that are, that is, not held against the Cremonese standard. To me, this is evidence that people who understand the chemistry and the lab work can make even the cold mix stuff work. Cooked rosinate oil varnishes have a significantly broader margin of error, but in my years of working on this "problem" I have made failed batches, too. 

At the end of the day, Michelman was a genius chemist who did the best he could with his knowledge and skills and did so in good faith. All of the slander he has suffered over the years by people who simply couldn't follow the directions, read between the lines, and consult broader source material on the subject is wrong. They have no one to blame their failures on but themselves. 

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  • 3 weeks later...

I will try to make 2 rosin.

One red with cochineal and one yellow with turmeric.

1st step is the Rosin dissolved in water and 1%KOH

20210327_201354.thumb.jpg.e056eb882d709f6690da7701542dd879.jpg

I use quantity for 1.5 liter.

Now I need to wait few days.

I wonder about the quantity of pigments and if  I need to extract them with alcohol or to put them direct in the liquid.

I intend to precipitate the red with Zn, and the yellow with Al and Fe.

 

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6 minutes ago, David A.T. said:

I will try to make 2 rosin.

One red with cochineal and one yellow with turmeric.

1st step is the Rosin dissolved in water and 1%KOH

20210327_201354.thumb.jpg.e056eb882d709f6690da7701542dd879.jpg

I use quantity for 1.5 liter.

Now I need to wait few days.

I wonder about the quantity of pigments and if  I need to extract them with alcohol or to put them direct in the liquid.

I intend to precipitate the red with Zn, and the yellow with Al and Fe.

 

Michelman's original text, as well as my article, make it very clear how much dyestuff is needed and when it is introduced. You don't have to reinvent the wheel.

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