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joerobson
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4 minutes ago, Peter K-G said:

Resin and turp?, cooked?, how? 

Have to ask

 

Raw resin fractions are extracted by mild heat and solvent extraction. First 2 are alcohol soluble. 3 and 4 are turpentine soluble.  The extraction process does not change the chemical or physical characteristics of the resin.

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I think it is time to quote Sir David Burgess.... I remember it very well, after Elizabeth II crowning, after having some bottles of Tattinger champagne, someone started talking about varnish, and Sir Burgess admonished the gent in a very phlegmatic way: "GENTLEMEN NEVER TALK ABOUT VARNISH".  The Queen loved it and authorized Sir Burgess to write in his labels "BY APPOINTMENT TO HM THE QUEEN". I was there.... history was being made in front of my eyes!!!

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1 minute ago, joerobson said:

Raw resin fractions are extracted by mild heat and solvent extraction. First 2 are alcohol soluble. 3 and 4 are turpentine soluble.  The extraction process does not change the chemical or physical characteristics of the resin.

Thanks!

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3 hours ago, sospiri said:

Why do recent research papers focus on entirely different preconceptions?

Echard et al and the oil ground. And the other researchers promoting the contemporary Cremona ground?

Something is very wrong somewhere.

Those recent researches focus on Strad.   

The use ground minerals (leaving the question of use as pore fill, ground layer, are filler in varnish) is well document in paintings and instruments in Italy during the period of classical Cremona making.  And, there are some Cremona instruments were it's well documented.

However, there appear to be at least some Stradivari instruments were such minerals don't fill the pores.

Many people currently expand the context of that one quite limited fact to such minerals weren't used in a much more general way.

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1 hour ago, joerobson said:

I am open to almost all questions. 

Have you tried Linseed oil ground? Do you not believe, as I do, that it was the tradition in Cremona from the 16th to 18th Century?

If not, not, why?

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19 minutes ago, David Beard said:

Those recent researches focus on Strad.   

The use ground minerals (leaving the question of use as pore fill, ground layer, are filler in varnish) is well document in paintings and instruments in Italy during the period of classical Cremona making.  And, there are some Cremona instruments were it's well documented.

However, there appear to be at least some Stradivari instruments were such minerals don't fill the pores.

Many people currently expand the context of that one quite limited fact to such minerals weren't used in a much more general way.

Those papers conflicted with Echard et al.

Why?

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6 minutes ago, Peter K-G said:

Why should we assume that there was a standard Cremonese varnish/ground formula that lasted 200 years.

Basically, yes.  However, some of the most studied Strad finishes seem to be different than the broader instrument finishing practices.

 

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33 minutes ago, David Beard said:

Basically, yes.  However, some of the most studied Strad finishes seem to be different than the broader instrument finishing practices.

 

But, I would add that the evidence supports more the idea that there was a fairly uniform general approach.  But that at each stage of work the exact materials and recipes were wide open.

So staining or sizing wood could be done with any number of stains or sizes.    A role for 'white grounds' could be fufilled by a range of minerals, etc.

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6 minutes ago, David Beard said:

IMHO, that involves minerals.

I agree. regarding the the decorated Amati's - it seems logical they would have applied some sort of gesso to isolate the bare wood from the painted layer and provide a surface to paint on. Standard working methods well documented in many period sources. 

Are there any scientific studies of the decorated Amati's? I agree with Manfio, they have a really special quality 

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54 minutes ago, sospiri said:

Those papers conflicted with Echard et al.

Why?

Most researchers so far have used limited tests, with limited resolution.  Layers get blurred and confused.  There is also a difficultly in terminology.  For general Italian arts, terms like ground and size have rather established meanings.  The modern violin world borrows the same language, but tends to go its own way in using the words.

 

However, we begin to see studies that combine multiple tests and high resolution imagery to give a strong stratigraphic analysis.

Hopefully this kind of work will continue and give us a clearer and broader window on historical finishes.

 

 

 

 

2018 Micro Imaging of Finish Layers supporting.pdf

 

2018 Micro Imaging of Finish Layers Main Article.pdf

 

 

 

2018 Micro Imaging of Finish Layers Main Article.pdf

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50 minutes ago, Urban Luthier said:

I agree. regarding the the decorated Amati's - it seems logical they would have applied some sort of gesso to isolate the bare wood from the painted layer and provide a surface to paint on. Standard working methods well documented in many period sources. 

Are there any scientific studies of the decorated Amati's? I agree with Manfio, they have a really special quality 

See:  https://heritagesciencejournal.springeropen.com/articles/10.1186/s40494-020-00460-6

Also see:  https://www.sciencedirect.com/science/article/abs/pii/S0584854796015960

The latter includes TXRF data for a number of instrument varnishes including an Amati c.1560.

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In reply to David Beard,

Very different from Échard's observations. 

Two different techniques for violin and cello or two different makers?

Also the resesrchers give no specific reference to Échard's observations or working hypothesis. Why is that? Rivalry?

 This is the current Cremona School ground concept used by Davide Sora and Edgar Russ.

f you listen to Edgar Russ's violins, they have a very bright sound, to me it is harsh and nothing like the 1560 Gasparo da Salò or any Strad or del Gesù, which are very tonally rich; Dark + Bright, but attenuated in the mid-range somewhat.

If it's overdone, the sound is muddy and that seems to be the consensus. So there is certainly agreement about that. But if done correctly, the oil ground is a specific sound and feel that you might find very interesting.

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The varnish experts and makers become cagy in telling us what they do.  It is always this way.  I enjoy the comedy.

Don Noon gives us the essential features of what the varnish system must consist of.  I would add that the process must be simple.

Davud Beard has included a very useful paper by Fiocco.  His team (Fiocco's) has published several recent papers including a couple using the OCT method.  The direction of research has moved from Echard to Fiocco.  The enclosed paper is of an Andrea Amati cello with a gypsum ground, some colored particles over that, and then the varnish which has some colored particles.  Other Fiocco papers indicate a protein in/on the wood.

It is all fairly simple when you get down to it.  There are a few makers, like Hargrave, that will tell you everything that they do.  Most makers get a coughing fit when asked to reveal what they do.

Mike D

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8 minutes ago, sospiri said:

Very different from Échard's observations. 

Two different techniques for violin and cello or two different makers?

Also the resesrchers give no specific reference to Échard's observations or working hypothesis. Why is that? Rivalry?

 There are 4 references to Echard's work in the Fiocco paper.  Bruce Tai's 2007 review paper is also referenced.  That is pretty good.

Mike D

 

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1 hour ago, Mike_Danielson said:

The varnish experts and makers become cagy in telling us what they do.  It is always this way.  I enjoy the comedy.

Don Noon gives us the essential features of what the varnish system must consist of.  I would add that the process must be simple.

Davud Beard has included a very useful paper by Fiocco.  His team (Fiocco's) has published several recent papers including a couple using the OCT method.  The direction of research has moved from Echard to Fiocco.  The enclosed paper is of an Andrea Amati cello with a gypsum ground, some colored particles over that, and then the varnish which has some colored particles.  Other Fiocco papers indicate a protein in/on the wood.

It is all fairly simple when you get down to it.  There are a few makers, like Hargrave, that will tell you everything that they do.  Most makers get a coughing fit when asked to reveal what they do.

Mike D

Even with all the same materials and completed varnish, I think application method and the end result your trying to achieve is a major factor.

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1 hour ago, sospiri said:

In reply to David Beard,

Very different from Échard's observations. 

Two different techniques for violin and cello or two different makers?

Also the resesrchers give no specific reference to Échard's observations or working hypothesis. Why is that? Rivalry?

 This is the current Cremona School ground concept used by Davide Sora and Edgar Russ.

f you listen to Edgar Russ's violins, they have a very bright sound, to me it is harsh and nothing like the 1560 Gasparo da Salò or any Strad or del Gesù, which are very tonally rich; Dark + Bright, but attenuated in the mid-range somewhat.

If it's overdone, the sound is muddy and that seems to be the consensus. So there is certainly agreement about that. But if done correctly, the oil ground is a specific sound and feel that you might find very interesting.

I don't have any comment on modern Cremona practices.

In my opinion, significant use of minerals at several stages of finishing was most likely normal practice for the old Cremona making, including most Strads.

Though I an certainly willing to be proved wrong as more evidence accumulates, I bet is that we will learn in time that examples without minerals are by no means the majority.  Some Strads do have an extra clarity of appearance that might come either from no minerals, or less minerals, or finer minerals.  But I'm along way from being convinced this was normal or common.

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I have two theories explaining Echard’s detection of linseed oil in the ground. The first is that he is detecting a thin emulsion of linseed oil and an organic medium used as a wood primer. The second is that his method of detecting linseed oil is being confused by an organic medium that interferes with forming the spectral profile he uses. 

I am waiting for confirmation of his detection by another research group using a different method if possible.

As for particulates in the ground, they are there in Cremonese violins because that was the standard artistic method of the day. I agree with Joe that they are not needed to get a great looking instrument. As I said before, are you trying to reproduce an historically accurate mock-up or a great looking instrument, perhaps better than Strad?
 

 

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