Stradivari Varnish oil/resin ratio


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On 8/5/2020 at 12:49 PM, Mike_Danielson said:

If you read the Nagyvary review of the B & G book, you find that it was never submitted to a peer review before being published.  This is a serious problem with the B&G book.  So, I do not take it very seriously.

Were any of Nagyvary's various claims peer reviewed?

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I think the scatter in conclusions is primarily due to error in interpreting the data, namely the location of detected components and in assigning them to discrete layers. There is also the issue of subtle differences among instruments even from the same shop. Perhaps the answer would be to pass around one instrument to all the labs and have it always available for analysis. Anyone have a spare Strad? :D

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10 hours ago, John Harte said:

Echard has employed electron microscope in his studies.  See p.108 onwards in his Ph.D. thesis. 

It also seems that Brandmair employed SEM/EDX.  This is listed in her summaries of analytical results for the various samples considered in her section of Stradivari Varnish.  She also mentions it being used for the mapping of inorganic compounds.

Sem/edx is the spectrum analysis and not the em picture. I suppose that brandmair would have shown those pictures if she made them, but who knows. The pictures are no objective analytical method, but imo can be quite useful. It is also possible that the particulate layer detected by the pictures is the actual varnish layer and the upper layer just the fp. 

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My experience is that if you use a very lean varnish (4:1),it sets so quickly that you have no chance to varnish a cello. Adding a little bit of raw linseed oil slows the tack time considerably without changing the proportions so much. 

Brigitte Brandmair, with whom I talked about that, thinks it would explain the different crackling found on cellos vs violins.

As for a lean varnish being too brittle, I noticed my varnish becomes tougher with time, and the various layers of polish melted into the varnish probably softened it a little. 

 

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1 hour ago, pbelin said:

My experience is that if you use a very lean varnish (4:1),it sets so quickly that you have no chance to varnish a cello. Adding a little bit of raw linseed oil slows the tack time considerably without changing the proportions so much. 

Brigitte Brandmair, with whom I talked about that, thinks it would explain the different crackling found on cellos vs violins.

As for a lean varnish being too brittle, I noticed my varnish becomes tougher with time, and the various layers of polish melted into the varnish probably softened it a little. 

 

I agree Paul. Talking with Brigitte in person,  during a visit to Germany a few years ago,  she also mentioned the Stradivari cello varnish had more oil than the Stradivari violins she had tested.  Which is logical for varnishing a larger instrument.   

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On 8/7/2020 at 7:00 AM, pbelin said:

My experience is that if you use a very lean varnish (4:1),it sets so quickly that you have no chance to varnish a cello. Adding a little bit of raw linseed oil slows the tack time considerably without changing the proportions so much. 

Brigitte Brandmair, with whom I talked about that, thinks it would explain the different crackling found on cellos vs violins.

As for a lean varnish being too brittle, I noticed my varnish becomes tougher with time, and the various layers of polish melted into the varnish probably softened it a little. 

 

 

8 hours ago, Mike_Danielson said:

Here is another example of Occam's Razor:  instead of inventing another varnish composition for cellos, why not use more coates of the violin varnish?  Then, you will get a thicker and darker varnish.  It may age differently.

Mike D

Paul’s point is about slowing drying time for a large area which needs another razor, as it were. :rolleyes:

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About 20 years ago I introduced a 4 resin to 1 oil varnish to the violin making community.   This is the final sealer for the Balsam Ground.  Called the Balsam Ground Varnish

  Some makers have been successful at using this for violin and viola.  Application techniques vary as you might guess.   The final finish differs from that which we see on a Stradivari instrument.

The research behind the varnish was two-fold.   First I wanted to see how resin rich a varnish I could make and have it be liquid and usable at room temperature.  

Second I was looking for the surface and adhesion characteristics of the Cremonese ground.

I feel reasonably successful on both counts.

If you attempt to make such a varnish you will need to experiment with the type of resin and the cooking method.

on we go,

Joe

 

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5 minutes ago, Bodacious Cowboy said:

Liquid and usable at room temperature without a solvent thinner?

It does flow, but it is incredibly thick. Joe's directions for his system suggest dilution. 

I have no commercial interest in Joe's enterprise. But I will say that his system produces stunning results. I am a convert. 

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On ‎8‎/‎6‎/‎2020 at 6:01 PM, uncle duke said:

What kind of oil did you use?  If you have put the cold application on a violin yet did it sink down into the spruce when applied?

Raw Linseed oil. If you apply very small amounts and spread it all over the spruce and rub for a few minutes, it forms a seal. Hence Stradivari's very slight penetration of the spruce with the oil. 30 microns is very thin.

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On 8/8/2020 at 2:25 AM, JacksonMaberry said:

Take varnish, add a few extra drops of oil and maybe some solvent or essential oils to slow tacking, varnish cello. 

I will agree that adding a little more oil to the varnish, after cooking,  can increase brushability and/or spreading time, seemingly without any harmful effects. But of course, it will increase the oil-to-resin ratio, should someone be obsessed with a precise ratio.

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11 minutes ago, David Burgess said:

I will agree that adding a little more oil to the varnish, after cooking,  can increase brushing or spreading time, seemingly without any harmful effects. But of course, it will increase the oil-to-resin ratio, should someone be obsessed with a precise ratio.

Definitely worth noting and considering during the process, keeping the fat over lean rule in mind. My only point in mentioning this is to suggest a more likely "razor" than Mike Danielson pitched. 

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On 8/7/2020 at 11:32 PM, Mike_Danielson said:

Here is another example of Occam's Razor:  instead of inventing another varnish composition for cellos, why not use more coates of the violin varnish?  Then, you will get a thicker and darker varnish.  It may age differently.

Mike D

A darker varnish on my cellos, than on my violins, is not what I am looking for. The varnish on my recent violins is already pretty dark (having been made so upon the advice of some of my most respected colleagues).

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18 hours ago, Bodacious Cowboy said:

Wow. That’s a bit mind boggling.

My boggled mind was thinking about an 80:20 mix of colophony and oil. So essentially 80% processed resin with all the volatiles driven off, and solid at room temperature. This would contrast to using unprocessed pine resin, or venice/strasbourg turpentine as the resin, which would be usable as a varnish in an 80:20 mix. But in this scenario, the resin/oil  weight ratio wouldn't be 80:20 after cooking, when all the volatiles had been driven off from the resin, would it? This is what confuses me about the Brandmair results. Are they saying that the varnish had an 80:20 weight ratio on application? In which case, surely some solvent must have been used? I confess I don't have the book. Also, I don't expect Joe to reply if it would involve revealing or hinting at any commercially sensitive info.

Sorry if this seems like the babbling of an incoherent mind.

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1 hour ago, Bodacious Cowboy said:

My boggled mind was thinking about an 80:20 mix of colophony and oil. So essentially 80% processed resin with all the volatiles driven off, and solid at room temperature.

I wouldn't expect that mix to be easily brushable, but it might be easily sprayable. Let's not pretend that the Cremonese didn't have compressed air available, with the ability to spray from lung-powered atomizers,  to things like the compressed air used for pipe organs or forges which had already been in use for centuries.

Here's the type of breath-powered atomizer which I used from time to time in the Weisshaar shop, and still have.

https://freeflight.org/Library/TechLibrary/AirBrush,MouthOperated.pdf

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46 minutes ago, David Burgess said:

I wouldn't expect that mix to be easily brushable, but it might be easily sprayable. Let's not pretend that the Cremonese didn't have compressed air available, with the ability to spray from lung-powered atomizers,  to things like the compressed air used for pipe organs or forges which had already been in use for centuries.

Here's the type of breath-powered atomizer which I used from time to time in the Weisshaar shop, and still have.

https://freeflight.org/Library/TechLibrary/AirBrush,MouthOperated.pdf

Thanks. I do know one or two folks that could help with supplying copious quantities of hot air. :D

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