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David Beard

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Everything posted by David Beard

  1. Thank you for these last posts. For me, one of the most valuable aspects of reading MN is hearing inside observations from guys like you and Bruce and others who have tons of experience with the old instruments. Feeling grateful for MN, David
  2. I must confess I'm confused by the distinction between good beautiful deep flame and 'burned in' flame?
  3. I'm really not sure if these mean anything. It's quite possible that the black is later dirt contamination after the edges are worn down abit. The Harrison example below has a definite contrast between the red pores inside the purfling and the black on the edge, and it gives the appearance that at least some of the black pores are under the upper layers of varnish. But again, this could be a case of later dirt following wear, and then some touch up varnish. I've seen examples more to my point (I thought posted by you) where 1) the pores contrast strongly in red versus black, 2) the black seems to be mastic under original varnish. If such examples are really the way they left the maker's hand and not later effects, then the implication is that the red pores inside were made before purfling was installed and didn't get scraped or cut down later, and that the outer edge did get scraped down or reduced -- but that mastic got in the pores after the scraping. For me, these details feed into a growing personal suspicion that not only was the channeling complete before purfling, but that also some phases of finishing had occured. It seems possible to me that in most classical instruments the pore fill and reflective effects were achieved before the purfling. Perhaps some instruments had complete ground before purfling. The Maggini examples posted earlier by Bruce give me the impression that the purfling cuts into and interupts otherwise continuous and preestablished wood finish. Further, the pores in the interior region appear to have been mostly but imperfectly protected from the mastic. Again supporting the idea that finsh was already in place. What a great and interesting picture!! Does the top plate tightly abut to the neck? Is the join between neck and plate straight? Or does it continue the curve of the top edge? To me this seems the more likely situation. pictures of Harrison Strad and a Maggini:
  4. Just wondering if people have any ideas why this shows up in some chemical studies of classical varnish. Ideas? I'm wondering both about the chemical form and the purpose?? Did they bleach the wood or a component of the varnish? Was it part of a pigment? Did they use simple salt?
  5. Interesting picture. Who's finish is it? I find the layers with different fracturing textures intriguing. From Bruce Tai's article and other sources, I'm inclined to believe the 'cheesey' fractures represent colloid or emulsive materials or other physical mixture of break properties, whille only the smooth fracture of the top layer could represent a clean unified material like linseed oil, resin, or a cooked varnish without particulates. Do others see these layers the same way??
  6. It's interesting to note that the upper colored varnish has preferentially survived better where the underlying wood texture is more porous.
  7. It seems very healthy indeed that this thread starts with a specific observation, and then asks if perhaps the new evidence indicates the old masters did things in a sequence and manor different then we usually assume!! Of course this one glue stain might represent some unique event that tells us nothing. But more likely it suggests this section of purfling was installed at a late stage in the making. It seems to me that other detailed pictures posted on MN have also suggested that purfling might have been installed latish, even after some phases of wood finishing are completed. I don't have the pictures in front of me at this moment, but I think Bruce has posted some very detailed corner pictures were you can see a reddish pore fill happening all the way to the inside edge of the purfling. But then on the rounded outer edge (but under clear or slightly colored varnish) you can see black pore fill. I'm guessing the black pores are from mastic used in the purfling and corner work. Further, there is a little zone between the outer side of purfling and black pores on the edge were the pores are clean. This might indicate a bit of scraping after the mastic on the outer side of the purfling. But the red pores on the inside edge aren't scraped away. Also, though this is tougher to be sure of, it seems that in many of the detailed pictures of edge work the 'reflective' effect seems to run very cleanly right up to the inside edge of purfling, as if it was in place before hand and then interrupted by the cut of the purfling channel.
  8. Would a very minimal application of a steel burnisher help?
  9. Beautiful sample! I'm still just experimenting with possibilities, so my actual experience is very limitied. But I find the idea of St Peter's Gold/dorata/golden tin attractive. It seems a straight foward techninique consistent with the broader and less mysterious art materials of the time. As your photo shows, the results can be very effective. As for protein sizes, I've not experienced the cloudiness issues Joe mentions. In my little varnish experiments I've found glue size or simple egg white are both easy devices to keep oil out of the wood grain and avoid the sort of featheriness or fuziness that seems to develop when pigmented oil contacts the wood grain. I've also thought (perhaps my imagination??) that either thin glue size or simple egg white seems to create a sort of clean optical connection between the wood and an upper layer of finish of most any kind. Thanks for showing the picture.
  10. Is this a typical texture for classical varnish? Great picture!
  11. Hi Brian, Even though you're trying to start from scratch and not to recreate, I would suggest that Cennini's Craftsman Handbook would be worth the read for your project. Violins weren't a 17th century invention, but more of a 16th century evolution of older instrument making. As such, Cennini’s presentation of the materials and practice of 15th century art are entirely relevant. He lays out the methods and purpose of grounds in art work. It's easy to see instrument making as part of the family, including ideas of glues and grounds and varnish. I would say that from their old point of view, one of the main goals of ground is to keep work 'lean'. Our modern bias is to think of a wood finish as mostly oils and resins. And modern paint is mostly oil with some pigment and some resins. If you look at the common general art practices at the time the violin and its precedents arose, the idea of paint and finishes was different. Paint was mostly mineral pigment with a minimum of protein binder. Oils and varnish had mostly only special exceptional purposes, either in special layers at the bottom of the work, or as an outer protective layer. Also, the modern art notion of 'lean' versus 'fat' is more or less discussed in terms of the amount of oil, oil being 'fat'. In the older view, 'lean' versus 'fat' is more like the difference between the grittiness of sand versus the smoothness or butteriness of clay. The gritty 'lean' character was considered the ideal. A ground provides a stable 'lean' under layer, and it provides a reflection of white light back up from the bottom layer to shine out through the pigment layers. Also, I think the bias toward 'one pot' versus layers is entirely modern. Reading source materials from the time, like Cennini, you realize that while their methods were often very effective and efficient, they were anything but lazy. They used materials from around the world, and elaborate processes. Good luck with the project. David
  12. Very useful. Thank you for posting it!
  13. Hi, Thanks for sharing your experience. So the glue didn't hold on a shocking blow? Was it brittle or thin? I am curious if fat is all bad in the glue? Some of the old recipes quoted on the web refer to rinsing out the fat, which implies starting with a fatty cheese and probably not getting all the fat out. Since casein is such a good emulsifier, it doesn't seem that fat would necessarily be a problem. A bit of fat might perhaps add a touch of flexibility and make a tougher joint. I guess a want to give this a good try before dismissing it. It would be too easy to try one variant and decide that was enough to make a judgment. Roger Hargrave makes a good argument for the glue. I'm willing to mess around with it some and see what happens. Any other observations from your experience would be most welcome. Thanks, David
  14. Hi, Just an experiment, so I don't mind 'over thinking it' and even going a bit crazy on the details. They slacked the burnt lime by agitated it into the water of the lime pit and letting it settle at the bottom and stay there a long time. The sediment at the bottom became lime putty, but needed to be agitated periodically and allowed to age. Letting lime putty age 3 years was not considered excessive. If the lime wasn't aged well, then lit bits of unslaked lime would lurk in the putty. If these little remaining pockets of unslaked lime finally hydrated in a finished work, the chemical reaction could generated a lot of sudden heat and a pop, creating little pits and flaws in the work. My worry is that I didn't start with unslaked lime. Maybe putting already slaked lime back into water won't yield good putty and lime water?? Also, I'm curious about the lime pit for more reasons then just making glue. You can easily bend wood by soaking it in the lime water. David
  15. Hi, The texture in these pictures is amazing to see! Thanks for making and posting them. David
  16. I want to try making a violin using cheese lime glue for everything except gluing the top to the ribs, and perhaps setting the neck. Any comments, experience, tips, etc would be much appreciated and very helpful. Some past threads have helpful info, particularly from Oded Kishony and Roger Hargrave. I also see discussion of other uses of casein and of using pure casein powder and alternate alkalis, but for now I’m interested in the lime and cheese variety of glue. … Starting with fat free milk. I add vinegar to curdle it, I then pour it through a strainer (cheese cloth) then wash the solids in fresh water and rinse in distilled water. I then slowly add the base while I mash the ingredients together with a mortar and pestle. The glue is ready when it feels slippery and slimy between your fingers. Dilute with distilled water. ….. Oded Kishony http://www.maestronet.com/forum/index.php?showtopic=316284&view=findpost&p=377053 ....the casein acid or the cheese will be granular, as you add the base it turns slippery and slimy so just keep mashing it and feeling for any granular particles, when it's all slippery it's done ….. Oded http://www.maestronet.com/forum/index.php?showtopic=316284&view=findpost&p=416340 Roger Hargrave article on casein glue: http://www.roger-hargrave.de/PDF/Artikel/Strad/Artikel_1984_02_Case_For_Casein_PDF.pdf Hargrave post on casein glue http://www.maestronet.com/forum/index.php?showtopic=319807&view=findpost&p=430298 Cennini on various kinds of glue, including animal glues and casein glue: http://www.noteaccess.com/Texts/Cennini/5.htm Searching around the web, the oldest recipes I could locate are very brief. They mostly say take some cheese (sometimes they say ‘old’ or ‘hard’) and mix with lime. Sometimes they also talk about rinsing the cheese in clear running water first to remove fat. This leaves me wondering if it matters much what kind of cheese is used, and if there are any particulars about the lime. Apparently cheese and lime glue is very ancient, and is reputed to be water proof/resistant. More modern sources on casein glues of various formulas don’t seem to consistently make the water resistant claim, so I wonder if that depends on the lime? I’m assuming that in ancient times there was not such a wide range of cheeses as today. I’m also guessing that the recipes would be more specific if the kind of cheese mattered much? To start experimenting, I’ll make some glue using fresh curds, and some glue using old Swiss cheese rinds that have been allowed to harden and sweat out most all the remaining whey. I’m curious if one or the other will produce a more water resistant glue. To get started on the lime, I made a little 2 foot by 3 foot lime pit using a big plastic container. I filled the bottom with water and then stirred in a bag of hydrated lime. I’ve got about 4 inches of lime putty now at the bottom of the pit, with 4 or 5 inches of lime water above it. I’m hoping I haven’t made a big mistake by short cutting on the lime pit. I skipped the difficultly of using unslaked quicklime, and I’ve only let my pit age for 2 months. Still, I now have a ready supply of lime putty, lime water, and milk of lime as thick or thin as desired. I’m guessing that some of the strength of lime and cheese glue comes from having a bit of lime putty in the mix, not just lime water or very thin milk of lime. I’ll have to experiment with the balance of lime and water. Thanks, David
  17. I guess that like many folk, I’m fond of research that I see as supporting my biases and lines of thought I’m already pursuing. In this sense, I’m very fond of Bruce's paper as it supports the idea of a complex of layers (i.e. chart on p.131 and pictures on p.137 ), and it seems to indicate a system that is very much about ground particles. My own bias is toward seeing classical varnish as consistent with its time and place of origin. I want to understand the wood finishing of Strad and Del Gesu as at most a variation on the Andrea Amati’s, with his in turn being consistent as refinement/variation on broader and older common practices. As such, I’ve looked to Cennini and similar sources to gain some sense of the common paradigm for art materials at the time. Given such sources, I don’t think it too wild to suggest the general art materials paradigm in the time of Andrea Amati and just before was: Surface preparation Then Sizing Then a lime or similar mineral white gesso with a size or protein binder Then ground pigments in protein binder Then perhaps glazes of thinned pigment in oils or resins Then protective clear uncolored ‘varnish’ --this word seemingly reserved for cooked combos of resin and drying oil. The paradigm before Andrea and at his time seems to have used linseed oil, but only as a special purpose ingredient, not as the fundamental binder in most work. The approximately 2 centuries of classical making correspond with a shift toward replacing protein pigment binder with oil and resin binding. I’m sure someone might take exception, but I don’t believe this summary of the general art materials paradigm is particularly controversial. My bias is to try and understand the classical finishes as variations within this basic framework. At minimum, the gesso and pigmentation techniques must be varied for transparency. But then we still need to provide for the yellow under color. This is outside the most basic paradigm, but they did have a wide spread practice of yellowing tin to create an artificial gold, ‘golden tin’ or stagno dorato. One very basic recipe for stagno dorato is cooked linseed with saffron and bit of aloe for color -- applied hot. From this I would like to see classical finish as variations of the following: 1) wood prep – always scraping, sometimes also filling 2) size 3) some variation on a stagno dorato 4) gesso – with ‘lean’ particles manipulated and chosen to go transparent with wetting by a clear glaze – leaving only a brightening affect 5) color layer(s)as one or more glazes 6) ‘white water’ varnish To me, this seems like the minimum complexity that could be consistent with the historical context, and the observed features of classical varnish. The details in Bruce’s paper seem to reconcile easily with these kinds of expectations. Particularly, I find the ideas of levgation and super fine grinding very helpful. David
  18. I love that phrase! Do you have a working 'grammar of the arch' for yourself? David
  19. It doesn't seem like historical instruments were graded so regularly. I for one would be grateful to hear the reasoning you allude to. Thanks...
  20. I'm not sure these measures relate to the 'lively' quality you mentioned. Aren't these more measures of the force level where the elastic behavior breaks down and gives way to breakage or plastic behavior? Wouldn't tests for the 'liveliness' or actual elasticity require bouncing the bridge, or bouncing something off of the bridge -- perhaps in a preloaded setup to simulate the conditions of a bridge on a violin? David
  21. It may be that your sense of 'lively' versus 'dead' is of great importance to the sound. Just speculation, but I would guess that this intuition would correspond to elasticity instead of stiffness. 'Liveliness' should indicate that a very high percent of energy put into deflecting the wood comes out again as the deflection restores. I believe that means that two bridges of equal mass might give the same 'pitch' when dropped -- showing equal stiffness, yet still have different liveliness -- reflecting the ratio of energy in to energy out. Since beyond filtering the signal from the strings, the main job of the bridge is to transmit energy, this liveliness may be one of the most important factors in a good bridge. David
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