MikeC Posted February 25, 2011 Report Share Posted February 25, 2011 There's always lots of talk about the ground. What I want to know is what is meant when the ground is described as being refractive? or is the the varnish and not the ground? Which ever. What is meant by that term? reflective I can understand, but refractive? Quote Link to comment Share on other sites More sharing options...
Bernhard Ritschard Posted February 25, 2011 Report Share Posted February 25, 2011 http://en.wikipedia....wiki/Refraction http://en.wikipedia....ection_(physics) As you can see, in a reflective ground you would only see yourself, as in a mirror... A refractive ground allows you to see deeply into the wood. Quote Link to comment Share on other sites More sharing options...
Brian McLinden Posted February 25, 2011 Report Share Posted February 25, 2011 There's always lots of talk about the ground. What I want to know is what is meant when the ground is described as being refractive? or is the the varnish and not the ground? Which ever. What is meant by that term? reflective I can understand, but refractive? I haven't the slightest idea. I do know that multiple thin films, as in the shell of the beetle, produces iridescence - and maybe that could be especially beautifying to violins. Quote Link to comment Share on other sites More sharing options...
JimMurphy Posted February 25, 2011 Report Share Posted February 25, 2011 Mike, Refraction simply refers to how light ray velocity & wavelength get altered when entering/leaving different mediums [wood, varnish, etc.]. A nice shimmering optical effect is seen if the refractive indices are just right. "Reflection" is just a change in 'direction' only, not velocity & wavelength. With respect to violin varnish/ground refraction, maybe there's two schools of thought: (1) some credit 'minerals' in the ground for the optical effect in old Cremonese varnish; (2) others say it's something they did to enhance wood grain Chatoyancy. Jim Quote Link to comment Share on other sites More sharing options...
MikeC Posted February 25, 2011 Author Report Share Posted February 25, 2011 when I hear the word refracting I was thinking of how a prism breaks white light into a rainbow so I was wondering if that meant that you can see rainbow colors under the varnish. Thanks for explaining it to me. reading back over the responses now I'm a little confused again. I've heard the ground (Cremona) is reflective and refractive. How can it be both? Someday I'm going to see one in person and then I'll know what everyone is talking about! Quote Link to comment Share on other sites More sharing options...
Bruce Carlson Posted February 26, 2011 Report Share Posted February 26, 2011 when I hear the word refracting I was thinking of how a prism breaks white light into a rainbow so I was wondering if that meant that you can see rainbow colors under the varnish. Thanks for explaining it to me. reading back over the responses now I'm a little confused again. I've heard the ground (Cremona) is reflective and refractive. How can it be both? Someday I'm going to see one in person and then I'll know what everyone is talking about! Hi Mike, Here are two shots of the same corner on a Guarneri 'del Gesù'. The only change was the direction of lighting. As for reflective I sometimes use the word 'luminous' like photographs 3 and 4 of a Nicola Amati. Bruce Quote Link to comment Share on other sites More sharing options...
actonern Posted February 26, 2011 Report Share Posted February 26, 2011 Thank you Bruce! Fantastic as always... E Quote Link to comment Share on other sites More sharing options...
COB3 Posted February 26, 2011 Report Share Posted February 26, 2011 As for reflective I sometimes use the word 'luminous' like photographs 3 and 4 of a Nicola Amati. Bruce Thanks for the great photos-- I found it encouraging to see the splice in the purfling. :-) Quote Link to comment Share on other sites More sharing options...
McBenet Posted February 26, 2011 Report Share Posted February 26, 2011 Hi Mike, Here are two shots of the same corner on a Guarneri 'del Gesù'. The only change was the direction of lighting. As for reflective I sometimes use the word 'luminous' like photographs 3 and 4 of a Nicola Amati. Bruce I'm curious Bruce, can the texture that is seen in photo #4 be felt by touching with the finger tips, or is it only "seen"? -----Barry Quote Link to comment Share on other sites More sharing options...
Michael K. Posted February 26, 2011 Report Share Posted February 26, 2011 Very nice photos Bruce! That is allways a pleasure to see it in the way we didn`t find it in any books. It would be nice to see anytime the "dichroism" efect of old masterinstruments on HD-video. Quote Link to comment Share on other sites More sharing options...
Bruce Carlson Posted February 26, 2011 Report Share Posted February 26, 2011 I'm curious Bruce, can the texture that is seen in photo #4 be felt by touching with the finger tips, or is it only "seen"? -----Barry It's a visual effect, the varnish surface is fairly smooth. There are occasions where the surface texture plays a role but in this particular area there is no real craquelure or roughness to speak of. Bruce Here are four shots of a Stradivari violin with only change in light direction. Quote Link to comment Share on other sites More sharing options...
MikeC Posted February 27, 2011 Author Report Share Posted February 27, 2011 Bruce thanks for the pictures! In the first two I can see the chatoyancy of the maple, is that what is meant by refraction? or is the refractive quality something that enhances the chatoyancy? The wood under the varnish looks white especially the third picture under the splice in the purfling. Hard to believe there was ever any suntanning or staining of the wood. Are the colors accurate? It looks like a pastel orange. Do you have access to these violins? If you do then a video close up turning them under some good lighting would be really interesting to see. Quote Link to comment Share on other sites More sharing options...
Bruce Carlson Posted February 28, 2011 Report Share Posted February 28, 2011 Bruce thanks for the pictures! In the first two I can see the chatoyancy of the maple, is that what is meant by refraction? or is the refractive quality something that enhances the chatoyancy? The wood under the varnish looks white especially the third picture under the splice in the purfling. Hard to believe there was ever any suntanning or staining of the wood. Are the colors accurate? It looks like a pastel orange. Do you have access to these violins? If you do then a video close up turning them under some good lighting would be really interesting to see. Mike, Most of the time these violins are in for only short periods. I wouldn't say that the wood is white underneath but more a light brown. The colors are not perfect and if anything, even after some correction, they are always a little too yellow and red. This particular violin from c.1714 has a tinge of pink and pastel orange which is not easy to photograph. I don't know what kind of a video I could produce but maybe I should try. Bruce Quote Link to comment Share on other sites More sharing options...
MikeC Posted February 28, 2011 Author Report Share Posted February 28, 2011 Hi Bruce As for a video I was just thinking it would be more like seeing the instrument in person as opposed to just looking at a still photo because you could see the reflections and the movement in the curl of the maple as it is moved around in front of the camera. You probably already know but most flourescent lights give off a greenish tint and most incandesent bulbs give off a yellowish tint. I don't know about the flash of a camera. But those are things that can effect the colors in a photo. To get the best color accuracy maybe not using a flash and just shooting under a light that is made to have something like the spectrum of natural daylight. Quote Link to comment Share on other sites More sharing options...
CT Dolan Posted February 28, 2011 Report Share Posted February 28, 2011 Mike, I've seen one, up close and personal, in artificial and natural light. It was a Peter Guarneri of Mantua, and of ALL these fellas, his finish has become my favorite. As far as I'm aware, Peter was heavy with the ground coat (lots of it, with a thin wash of intense color applied over top). As for appearance, I'd liken the effect of his ground coat to that of a cat's eye stone (providing a deep, translucent, scintillating effect to the wood). It was gorgeous. Chris Quote Link to comment Share on other sites More sharing options...
scordatura Posted February 28, 2011 Report Share Posted February 28, 2011 Mike, I've seen one, up close and personal, in artificial and natural light. It was a Peter Guarneri of Mantua, and of ALL these fellas, his finish has become my favorite. As far as I'm aware, Peter was heavy with the ground coat (lots of it, with a thin wash of intense color applied over top). As for appearance, I'd liken the effect of his ground coat to that of a cat's eye stone (providing a deep, translucent, scintillating effect to the wood). It was gorgeous. Chris I can second the opinion on Petrus of Mantua. I have seen two Petrus' of Mantua and one in particular had varnish to die for. I had the violin for a day and could not stop looking and marveling at the varnish, color, ground etc. I wish I had taken photos of that fiddle as example of what to do with the finish and ground. Quote Link to comment Share on other sites More sharing options...
Jeffrey Holmes Posted February 28, 2011 Report Share Posted February 28, 2011 As far as I'm aware, Peter was heavy with the ground coat (lots of it, with a thin wash of intense color applied over top). As for appearance, I'd liken the effect of his ground coat to that of a cat's eye stone (providing a deep, translucent, scintillating effect to the wood). It was gorgeous. Chris Chris; No argument with the appearance. P of M is one of my favorite makers... and two violins in particular rank up there with my all time favorites... but maybe I'm not understanding the "heavy ground coat" thing? Not exactly what I've observed... The color seems pretty close to the wood, as can be seen in the curl of the maple. Maybe a semantics thing and I misunderstand you? Quote Link to comment Share on other sites More sharing options...
Michael Darnton Posted February 28, 2011 Report Share Posted February 28, 2011 He's one of my faves, too. I have seen several with a very thick deep yellow varnish that I am convinced is just a very thick ground coat, something like I have seen on a couple of del Gesus, too, but with a thick color on top on the del Gesus. One of these POMs had spots around it in secluded places that appeared to be a stronger, brighter orange, and after I went around checking it under different lighting, I understood that what I was seeing was the remains of a thin wash of pure red that was probably the original color coat, almost completely gone. Quote Link to comment Share on other sites More sharing options...
Jeffrey Holmes Posted February 28, 2011 Report Share Posted February 28, 2011 He's one of my faves, too. I have seen several with a very thick deep yellow varnish that I am convinced is just a very thick ground coat, something like I have seen on a couple of del Gesus, too, but with a thick color on top on the del Gesus. One of these POMs had spots around it in secluded places that appeared to be a stronger, brighter orange, and after I went around checking it under different lighting, I understood that what I was seeing was the remains of a thin wash of pure red that was probably the original color coat, almost completely gone. OK.... Here we go with the semantics thing. Where shall we draw the line on "ground" and "isolation" coatings? To me, they are often slightly different things.. or at least they perform different functions. Quote Link to comment Share on other sites More sharing options...
Michael Darnton Posted February 28, 2011 Report Share Posted February 28, 2011 Well, for me the ground is the stuff immediately under the colored varnish that appears to be another coat of varnish, of varying thickness, mostly colorless but having a slight honey-colored cast that becomes more apparent with increasing thickness, and which appears to touch and slightly infiltrate the first couple of cell thicknesses of the wood. It can be so thick that pores are completely filled, or so thin that they aren't, and isn't inevitably in Cremonese work, or is so thin that it's not apparent. It's the stuff that I have always associated with the beautiful look of a nice Cremonese paint job, in that if it's not there, things don't look as nice as what people think of when they think of as a great Cremonese "varnish" job. The stuff that doesn't wear away quickly when the colored varnish wears. That's in the traditional understanding, not including all the varied "invisible" things that each new round of analyzers seem to come up with while simultaneously not seeing any of the "invisible" things that last year's favorite varnish analysis discovered. :-) Quote Link to comment Share on other sites More sharing options...
MikeC Posted February 28, 2011 Author Report Share Posted February 28, 2011 Michael I read a PDF that you wrote where you recomended multiple thin washes of shellac, one part shellac & 4 parts alcohol. It seems to have some of the main requirement. hardness / tough wear resistance, penetration into the upper layers of the wood, amber color. Since I don't know of anything better I'll probably go with that. Does shellac have any kind of refractive quality? Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted February 28, 2011 Report Share Posted February 28, 2011 OK.... Here we go with the semantics thing. Where shall we draw the line on "ground" and "isolation" coatings? To me, they are often slightly different things.. or at least they perform different functions. Jeffrey, Thank you, Jeffrey! Understanding and defining terms is key. One of the first things I told Joe Robson at the Workshop was the "noise" permeating varnishing. This comes from lots of sources because of several reasons which I need not raise. Darnton above is correct about what the ground layer is, but after this week I can say that sloppy work fills the pores. The superior examples were not filled. In fact, I now suspect that Robson may have found a way to improve on the Cremonese method by always avoiding pore filling glop. I leave that "heresy" for others to fight over. As for the isolation layer, this can be the topmost clear ground layer or the first clear varnish layer. Either (optically) isolates the ground and colored varnished regions. Note that Joe demonstrated how to shade the isolation layer to control the depth of the color. It was dramatic. Stay Tuned. Quote Link to comment Share on other sites More sharing options...
Michael Darnton Posted February 28, 2011 Report Share Posted February 28, 2011 Michael I read a PDF that you wrote where you recomended multiple thin washes of shellac, one part shellac & 4 parts alcohol. It seems to have some of the main requirement. hardness / tough wear resistance, penetration into the upper layers of the wood, amber color. Since I don't know of anything better I'll probably go with that. Does shellac have any kind of refractive quality? I find shellac technically adequate, but I'm not satisfied with the appearance in terms of the things being discussed in this thread, and am still working to find a better alternative. I'm no longer diluting it as much when I use it. Quote Link to comment Share on other sites More sharing options...
MikeC Posted February 28, 2011 Author Report Share Posted February 28, 2011 I find shellac technically adequate, but I'm not satisfied with the appearance in terms of the things being discussed in this thread, and am still working to find a better alternative. I'm no longer diluting it as much when I use it. What dilution would you reccomend? When I mixed some, one part from the bullseye can and 4 parts alcohol and let it sit for a while I noticed a cloudy layer at the bottom of the container and a clear layer on top. Any idea what causes that layering? Quote Link to comment Share on other sites More sharing options...
Michael Darnton Posted February 28, 2011 Report Share Posted February 28, 2011 That's probably wax, and you don't need it. I don't have an ideal dilution; thin enough to brush out well. Quote Link to comment Share on other sites More sharing options...
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