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Which ground to use


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32 minutes ago, David Burgess said:

How well does that ground hold up to perspiration?

Yaya we know your angle on sweat, but again I will state that burn through 3-4 layers of varnish, maybe more, is not really a concern of mine, and in tests of intentionally burned thru finish , getting down to the sugar ground, it seems to act similar to other burned through varnishes if applied properly. Again using a raw tool handle is a good test to see if something will get "gooey" as you state, and I admit a good test for "extremities" of what something will do, but in general I don't concern myself with it, any raw spot that get skin contact generally gets skinned over with "monkey oils" and start to discolor like any other burned down to raw wood varnish. Steel wool generally gives the best mimic of burn though, or very fine paper once you have got down a bit

One certainly could apply sugar wrong and then maybe someone who plays 10 hours a day for 20 years could prematurely burn through , say in the upper treble bout area, and then yes for a couple of sessions, there hand may feel a little tack, but , just like anything else, in short order raw wood would pick up dirt grime and dust and get ground into the raw wood, like any other burned varnish , and eventually the grime will displace or overcoat whatever is left of the ground, just like anything else.

Really the sugar layer is so thin and the adhesion with the shellac so good, that it seems when we get down to the level of complete burn through that if the shellac goes, it seems to take the surface sugar with it. The two kinda become one, similar with conifer based oil , but I like the shellac to xtra wall off the tubulars to prevent oil absorbtion, a double dissimiliar base. sugar also works very well with epoxy sealers

I will admit that if one put a heavy concentrate of sugar water on a violin, and then coated it with nothing else, that it would be a sticky mess, but thats not what we are doing and so it's not really apples and apples.

In short areas that have burned through act like other raw wood that has been burned through and areas that remain intact act like other varnish systems intact.

But again I will state that one could apply sugar "wrong" and use too much in proportion, or apply too may layers and that could be a problem.

 

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1 hour ago, Tostra said:

Thank you. I'll try it first, but I think maybe I'm more comfortable using spirit varnish on spruce and oil varnish on maple. It may be time for test pieces one of these days!

And Jezzupe I know. I just had to "split hairs"? Is that the saying in English? :-P
I did use hard sugar before, and I have to say I really like it. It's an option for sure!

 

Sure, nothing wrong with using two different things for spruce and maple. I don't believe it was common in the golden era, but neither were bandsaws and I like those a lot! Do what makes you happy and gets you where you want to go. 

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2 hours ago, jezzupe said:

Yaya we know your angle on sweat, but again I will state that burn through 3-4 layers of varnish, maybe more, is not really a concern of mine, and in tests of intentionally burned thru finish , getting down to the sugar ground, it seems to act similar to other burned through varnishes if applied properly. Again using a raw tool handle is a good test to see if something will get "gooey" as you state, and I admit a good test for "extremities" of what something will do, but in general I don't concern myself with it, any raw spot that get skin contact generally gets skinned over with "monkey oils" and start to discolor like any other burned down to raw wood varnish. Steel wool generally gives the best mimic of burn though, or very fine paper once you have got down a bit

One certainly could apply sugar wrong and then maybe someone who plays 10 hours a day for 20 years could prematurely burn through , say in the upper treble bout area, and then yes for a couple of sessions, there hand may feel a little tack, but , just like anything else, in short order raw wood would pick up dirt grime and dust and get ground into the raw wood, like any other burned varnish , and eventually the grime will displace or overcoat whatever is left of the ground, just like anything else.

Really the sugar layer is so thin and the adhesion with the shellac so good, that it seems when we get down to the level of complete burn through that if the shellac goes, it seems to take the surface sugar with it. The two kinda become one, similar with conifer based oil , but I like the shellac to xtra wall off the tubulars to prevent oil absorbtion, a double dissimiliar base. sugar also works very well with epoxy sealers

I will admit that if one put a heavy concentrate of sugar water on a violin, and then coated it with nothing else, that it would be a sticky mess, but thats not what we are doing and so it's not really apples and apples.

In short areas that have burned through act like other raw wood that has been burned through and areas that remain intact act like other varnish systems intact.

But again I will state that one could apply sugar "wrong" and use too much in proportion, or apply too may layers and that could be a problem.

 

The handed-down wisdom from those who were around before everything got corrupted from polishing and retouching, (I somewhat bridge that era), seems to be that the coating system on old Cremonese instruments consisted of an outer coating which wasn't very durable, and an underlying primary layer (sizing?) which was highly durable.

A water or perspiration soluble ground wouldn't seem to be a good fit.

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1 hour ago, David Burgess said:

The handed-down wisdom from those who were around before everything got corrupted from polishing and retouching, (I somewhat bridge that era), seems to be that the coating system on old Cremonese instruments consisted of an outer coating which wasn't very durable, and an underlying primary layer (sizing?) which was highly durable.

A water or perspiration soluble ground wouldn't seem to be a good fit.

Hi David

I'm curious do you know of solvents that it was not resistant to,  alcohol for example? Or is it impervious to everything? 

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2 hours ago, MikeC said:

Hi David

I'm curious do you know of solvents that it was not resistant to,  alcohol for example? Or is it impervious to everything? 

The one and only time I have done significant varnish "repair" on a spectacularly well-preserved Strad, was after the owner/user of this particular instrument had set it down on an alcohol rag. To me, it appeared that everything down to the wood had been removed, and that assumption worked out pretty well during the retouching process, when trying to "recreate" the surrounding coating system.

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6 hours ago, Michael_Molnar said:

I too wonder if this is the case, but I have not seen any researcher finding different grounds for spruce and maple. Maybe they never looked for it. Different grounds could create different appearances.

 

 

Spruce has from the beginning a very different appearance than maple.


Somehow I got tired to hang on the latest research results on the Italian ground to build my own formula. So what I am saying here is more my personal view. (1)  The top plate is the heart of the instrument and if the ground has anywhere an effect on the sound it is because it does something to the top. The same ground on maple might not enhance the flames that well and therefore I simply don’t see any problems in using something different. However i would not use different varnish.

—————

(1) Different researchers came to different results in terms of the use of minerals. Some say yes some say no. I can’t make a judgement who is right or why this came up. Over time I found it useless to make speculations about it in the void. Rather I get some ideas and put from there my formula together. 

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2 hours ago, David Burgess said:

The one and only time I have done significant varnish "repair" on a spectacularly well-preserved Strad, was after the owner/user of this particular instrument had set it down on an alcohol rag. To me, it appeared that everything down to the wood had been removed, and that assumption worked out pretty well during the retouching process, when trying to "recreate" the surrounding coating system.

Ah, so you’re the one who retouched that area.  I’ve always wondered who was the culprit.

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On 3/22/2022 at 2:36 AM, Tostra said:

I quite like the casein. The one thing I don't like is that it seems to be less refractive than the other two, which soak into the wood a bit

This has been a very interesting discussion.  I notice that the subject of Refractive Grounds does not seem to have been discussed.  Maybe knowledge is assumed. I for one would like to know more about this.  What does 'refractive' really mean and what grounds best achieve this?  

On my last build, I used a Mastic ground, albeit over casein, because it is supposed to be refractive.  I used the casein because I like the colour it gives.

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3 hours ago, Andreas Preuss said:

(1) Different researchers came to different results in terms of the use of minerals. Some say yes some say no. I can’t make a judgement who is right or why this came up.

As with most of these situations, maybe not quite as different as might be imagined...  The Barlow and Woodhouse particulate ground study was possibly the beginning of this but their interpretation of their data needs context.  When you consider the data itself, it's probably not at odds with what Brandmair and Echard found, or rather didn't find.

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2 hours ago, John Harte said:

As with most of these situations, maybe not quite as different as might be imagined...  The Barlow and Woodhouse particulate ground study was possibly the beginning of this but their interpretation of their data needs context.  When you consider the data itself, it's probably not at odds with what Brandmair and Echard found, or rather didn't find.

That seems a bit cryptic.  Can you explain what you mean by that?   I have some idea about the Barlow Woodhouse particulate ground but I could probably be wrong.  I think they misidentified the layers.  

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6 hours ago, David Burgess said:

The one and only time I have done significant varnish "repair" on a spectacularly well-preserved Strad, was after the owner/user of this particular instrument had set it down on an alcohol rag. To me, it appeared that everything down to the wood had been removed, and that assumption worked out pretty well during the retouching process, when trying to "recreate" the surrounding coating system.

Can you elaborate on how you recreated the surrounding coating system? 

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An enormous issue in research on classical varnishes is the lack of specimen control. The researchers examinations are halter skelter. They look at different instruments even by different makers, and rarely repeat looking at the same sample examined by a different lab group. As I have aid elsewhere, they need to focus on one instrument for starters and get agreement on it. 
 

My own reading uncovers good evidence that varnish techniques and materials changed, not dramatically, but subtly. My current basic model is (1) a colored wood stain, (2) clear rosin or thinned very lean varnish, (3) colored varnish. No intentional particulates.

 

 

 

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My personal favorite ground is after R. Hargrave. More or less based on the bass project, basically a organic Rubio red stain , plaster of Paris rubbed heavily on and heavily off , with a thick viscous dark cooked rosin/oil varnish applied very thick and rubbed off thin . Sun tanning before hand adds depth of color. 

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On 3/22/2022 at 12:59 PM, jezzupe said:

Yaya we know your angle on sweat, but again I will state that burn through 3-4 layers of varnish, maybe more, is not really a concern of mine, and in tests of intentionally burned thru finish , getting down to the sugar ground, it seems to act similar to other burned through varnishes if applied properly. Again using a raw tool handle is a good test to see if something will get "gooey" as you state, and I admit a good test for "extremities" of what something will do, but in general I don't concern myself with it, any raw spot that get skin contact generally gets skinned over with "monkey oils" and start to discolor like any other burned down to raw wood varnish. Steel wool generally gives the best mimic of burn though, or very fine paper once you have got down a bit

One certainly could apply sugar wrong and then maybe someone who plays 10 hours a day for 20 years could prematurely burn through , say in the upper treble bout area, and then yes for a couple of sessions, there hand may feel a little tack, but , just like anything else, in short order raw wood would pick up dirt grime and dust and get ground into the raw wood, like any other burned varnish , and eventually the grime will displace or overcoat whatever is left of the ground, just like anything else.

Really the sugar layer is so thin and the adhesion with the shellac so good, that it seems when we get down to the level of complete burn through that if the shellac goes, it seems to take the surface sugar with it. The two kinda become one, similar with conifer based oil , but I like the shellac to xtra wall off the tubulars to prevent oil absorbtion, a double dissimiliar base. sugar also works very well with epoxy sealers

I will admit that if one put a heavy concentrate of sugar water on a violin, and then coated it with nothing else, that it would be a sticky mess, but thats not what we are doing and so it's not really apples and apples.

In short areas that have burned through act like other raw wood that has been burned through and areas that remain intact act like other varnish systems intact.

But again I will state that one could apply sugar "wrong" and use too much in proportion, or apply too may layers and that could be a problem.

 

What ‘up ‘sides does the sugar ground have? Any that are clearly superior to other known grounds? Is it only for under shellac? 

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18 hours ago, MikeC said:

That seems a bit cryptic.  Can you explain what you mean by that?   I have some idea about the Barlow Woodhouse particulate ground but I could probably be wrong.  I think they misidentified the layers.  

The below are comments with particular reference to the Barlow and Woodhouse (B&W) study and my own viewing of various varnishes under Scanning Electron Microscope (SEM).  I should preface these comments by stating that I believe that Barlow and Woodhouse's work remains highly significant and don't believe that published comments by Brandmair and Echard are necessarily at odds with their observations.  It, to some extent, comes down to interpretation of what has been observed.

1.  There are various varnish formulations that, when viewed under SEM, can look like they might contain particulates and yet do not to any major extent, e.g., a thick casein layer, various emulsions, certain very short oil varnishes.  Under SEM these can look quite porous and crumbly.

2.  When viewing varnish layers under SEM, certain sizes/grounds beneath these layers can "disappear".  I have had the experience of viewing varnish samples under SEM that I created and not being able to see certain applied sizes/grounds that I knew were present.

3.  Oil varnishes containing pigments viewed under SEM do look like they contain particulates.

4.  From what I can see, the B&W particulate layers generally relate to material "on and above" the surface of the wood.  Echard and Brandmair clearly show the presence of material having penetrated the wood structure, which to me, begs the question as to whether B&W's observed particulate layers are in fact a "ground" layer.

5.  Jim Woodhouse has commented that the basis of the term "ground layer" occurred as a consequence of John Dilworth and Charles Beare referring to a "yellow ground".  I am not sure whether this yellow refers to varnish observed under natural light or UV light.  Either way, this is a too simplistic view of how ground appears as opposed to full varnishes.  In my opinion B&W's samples do, in some cases, almost certainly include more than just grounds or ground layers.

6.  I don't agree with B&W's interpretation of the layering in their SEM images.  They invariably refer to very smooth homogeneous upper layers as varnish which IMO is likely polish.  The particulate layers below are referred to as ground.  These appear, at times, to be 20 - 40µm thick (and maybe thicker) which is far thicker than what Echard or Brandmair have noted the initial Strad varnish/oil size/layer as measuring.  From my own experiences of looking at varnish under SEM, layers that are this thick are substantial, far thicker than any observable initial coating on any Strad that I have ever seen (i.e, as seen under visible light or UV).

7.  With specific reference to the various B&W SEM images of Strad samples, the particulate layer thickness (i.e., material depth sitting above the wood surface) in the Strad violin varnish sample appears to be in the region of 65µm.  The particulate layer thickness (i.e., material depth sitting above the wood surface minus what appears to be surface polish) in two other images of Strad varnish appears to be similar in one and slightly less in the other.  (I suspect that these relate to one or both of their Strad cello samples.) 

8.  Of the 15 or so samples that B&W studied, they found particulates in about half the samples.  From what B&W have published, we know that the Strad, Gofriller, and Rombouts samples contain particulates but the Amati does not.  The Rombouts (early C18th) and Strad (1711) samples featured in SEM images in the their publications are from cellos, which, at that time, were typically highly coloured.  The F. Gofriller sample (1720) was from a bass which was also likely highly coloured. 

9.  Of note is the opinion of various restorers that the particulate layer that B&W refer to is merely pigmented upper varnish..

I hope that this provides some clarification of my earlier post.

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John thank you for expanding on your earlier comment.    One thing I would add is that recently a link was posted here on MN,  I forget which thread,  which talked about powdered pumice and bone ash being added to oil varnish as a drying agent.  I thought perhaps that could explain a particulate presence in a varnish layer assuming B&W misidentified the varnish as ground.   As I recall in one of their SEM photos oil was identified in the upper cells (which would agree with Echard's finding)  then the 'ground' on top of the wood and then a thin layer of 'varnish' on top of the 'ground.   I suspect the layers should have been labeled wood, varnish, French polish.  

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On 3/22/2022 at 1:20 PM, David Burgess said:

The handed-down wisdom from those who were around before everything got corrupted from polishing and retouching, (I somewhat bridge that era), seems to be that the coating system on old Cremonese instruments consisted of an outer coating which wasn't very durable, and an underlying primary layer (sizing?) which was highly durable.

A water or perspiration soluble ground wouldn't seem to be a good fit.

No argument there, never said it was "Cremonese" or acted like it

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4 hours ago, James M. Jones said:

What ‘up ‘sides does the sugar ground have? Any that are clearly superior to other known grounds? Is it only for under shellac? 

I think the grain celebration is very good, and the sugar skin along with the shellac "wall off" and or make a good barrier coat that disallows oil seep , it also can be many different colors

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4 hours ago, MikeC said:

John thank you for expanding on your earlier comment.    One thing I would add is that recently a link was posted here on MN,  I forget which thread,  which talked about powdered pumice and bone ash being added to oil varnish as a drying agent.  I thought perhaps that could explain a particulate presence in a varnish layer assuming B&W misidentified the varnish as ground.   As I recall in one of their SEM photos oil was identified in the upper cells (which would agree with Echard's finding)  then the 'ground' on top of the wood and then a thin layer of 'varnish' on top of the 'ground.   I suspect the layers should have been labeled wood, varnish, French polish.  

I suspect that the oil in the upper cells that you refer to relates to a comment in the section covering the Rombouts sample.  Here B&W mention, 'There is little sign of penetration of the wood by the varnish.  The area labelled “oil” in the schematic is something which has been seen in a number of samples.  It closely resembles the residue seen just below the surface of (newly-prepared) wood which has been treated with linseed oil.  Doubtless other oils could leave a similar-looking residue.'

I do recall the study you refer to.  It wouldn't surprise me if particulates like pumice were present in these varnishes.  While it may act as a drying agent, there are also other reasons why it could be there.  In terms of drying agents, lead and manganese are another possibility, being a common theme at least in Strad varnish systems.  See: https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/abs/10.1002/xrs.2825

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I have to admit I've been doing more research rather than more tests. But I've come up with two things:

1) I've been making my casein ground way thicker than for instance Davide does. I think it might look much better when done like he shows in one of his videos, and I'm going to try that quite soon.

2) Spirit varnish and oil varnish does not look the same at all as I originally thought. I just tried brushing on Hammerl spirit varnish on one half of a piece of wood and work a very small amount of Old Wood Cremona varnish into the wood on the other half. It looked deeper in colour and refraction on both spruce and maple, but on spruce the two are more similar.

Could I safely ground an instrument this way?
With just a bit of varnish worked into the surface, will it soak into the wood? And will it dry properly?

I probably would use a single coat of casein, spirit varnish or the spirit varnish primer from Hammerl on the spruce to be sure before I work in oil varnish all over the instrument, but I still don't want uncured varnish in the maple.

I'm currently preparing a larger test, but I would like to hear people's opinions on using varnish as a ground. I don't want to dampen the instrument...

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1 hour ago, Tostra said:

I have to admit I've been doing more research rather than more tests. But I've come up with two things:

1) I've been making my casein ground way thicker than for instance Davide does. I think it might look much better when done like he shows in one of his videos, and I'm going to try that quite soon.

2) Spirit varnish and oil varnish does not look the same at all as I originally thought. I just tried brushing on Hammerl spirit varnish on one half of a piece of wood and work a very small amount of Old Wood Cremona varnish into the wood on the other half. It looked deeper in colour and refraction on both spruce and maple, but on spruce the two are more similar.

1. I do think there's a danger from applying a casein ground in too high a concentration. From other makers I have spoken with who have tried it, and some experiments myself, it does tend to contract so heavily upon drying, that it leads to a propensity for surface cracks.

2. Varying formulations and application methods of oil and spirit varnish can be visually indistinguishable. I still get some amusement from appraisals which state that the varnish is either spirit or oil. What it basically tells me is that the appraiser was a total duffer. :blink:

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I haven't been getting cracks, but I have definitely applied it very heavy. But I've been wiping it off so you have a matte wood finish primed with the casein, I doubt that can lead to cracking. It might led to bad refraction though...

And yeah, that is why I made sure to mention the brands in case people know them. And I hear that a lot as well. I guess they're basically the same once they're properly cured...

One more thing: I have cut a chamfer on the pieces, and on neither of the samples, oil of spirit, maple or spruce, do I see the ground seeping into the wood. If I can't see it, does that mean it doesn't soak in and I'm good to go with it on a violin if I wanted to use this method?
I still think I want to use something on the spruce, but this oil varnish thing sure is tempting

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1 hour ago, Tostra said:

I have to admit I've been doing more research rather than more tests. But I've come up with two things:

1) I've been making my casein ground way thicker than for instance Davide does. I think it might look much better when done like he shows in one of his videos, and I'm going to try that quite soon.

2) Spirit varnish and oil varnish does not look the same at all as I originally thought. I just tried brushing on Hammerl spirit varnish on one half of a piece of wood and work a very small amount of Old Wood Cremona varnish into the wood on the other half. It looked deeper in colour and refraction on both spruce and maple, but on spruce the two are more similar.

Could I safely ground an instrument this way?
With just a bit of varnish worked into the surface, will it soak into the wood? And will it dry properly?

I probably would use a single coat of casein, spirit varnish or the spirit varnish primer from Hammerl on the spruce to be sure before I work in oil varnish all over the instrument, but I still don't want uncured varnish in the maple.

I'm currently preparing a larger test, but I would like to hear people's opinions on using varnish as a ground. I don't want to dampen the instrument...

 

22 minutes ago, David Burgess said:

1. I do think there's a danger from applying a casein ground in too high a concentration. From other makers I have spoken with who have tried it, and some experiments myself, it does tend to contract so heavily upon drying, that it leads to a propensity for surface cracks.

 

What David says about the risk that casein in high concentration could cause craking problems would also be my warning, and I would also add an increase in varnish adhesion problems if the surface were somehow vitrified by casein.

Regarding the oil varnish used directly on the wood as ground, I think it is a delicate matter, surely it can be done but it all depends on the method of application and the properties (ratio&composition) of the varnish.

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