FredN

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  1. JOHA oil varnish from International Violin Co.

    Sounds like the varnish lacks sufficient surface tension, ie, internal pull of the varnish to level itself. A varnish with adequate surface tension, you can make a smear and watch as it slowly levels and gets a uniform surface.
  2. Bass bar tuning

    Did the older bass bars also cross a few growth lines like present? I guess common sense would say they did-
  3. Varnish book, recommend or not?

    The information is a good survey of varnishes and material, a little questionable using hard copal, not easy. Unless I missed it, the most likely use of rosin as the resin is not mentioned.
  4. Maestro Sora strikes again!

    And the purfling-
  5. The Purpose of Ground?

    To me, when somebody states "ground" I consider this the mineral portion found on surfaces of the inst. The simplest answer of its presence is the results of surface preparation. Evidence this is most likely the reason is analyses has shown it is not a complete surface cover, missing in places. Logic would indicate it is the residue of sanding/preparation of the surface. A paper on making sandpaper in 1800's (lost title) said the grit was collected on the sides of roads made with Belgian stone blocks from the grinding steel of wagon wheels. It mentions it was even graded to some degree in wind rows! The other likely source of grit would be pumice. I suspect the mineral content of each differs considerably and if both were found in areas of easy procurement might indicate merely the result of sanding. (David B, anyone who uses the term "tooth" is definitely into the literature)
  6. The Purpose of Ground?

    This is from Violin Varnish by Koen Padding, it is what I believe is much of the function, to prepare a suitable varnish surface.
  7. Varnish, quick and dirty.

    Hi Jim and Ip- article is from Protective and Decorative Coatings, edited by Joseph Mattiello, 5 vols, first 3 our interest, 1940's. Invaluable. fred
  8. Colophony shelf life

    Hi all- no doubt it does not compare to fresh distilled rosin, but more to powdered rosin exposed to air for many years resulting in reduced acidity and a darker color. Substances such as oil pine, methyl alcohol, turpentine, etc are separated in collecting distilled rosin, in stump extraction these have remained and could be present. The stumps are ground up and steam distilled for the products. Obviously it you're stuck like me in staying with things available in Strad's era, you have to keep in mind it wasn't available then.
  9. Colophony shelf life

    I would be careful when trying to obtain dark rosin, for much of it is wood rosin, stuff extracted from old stumps buried in the ground. I think Kremers is wood rosin. so If you just want color and not interested in anything else I found it similar to WW grade in cooking characteristics. Russia and Latvia sell dark rosin for industrial uses such as solder flux. This is rosin distilled from live trees..
  10. Varnish on the ground or in the wood

    Sorry, accidental submit; just finishing with these are components that have been noted to be present in Cremonese varnishes. Just speculating on the function of them.
  11. Varnish on the ground or in the wood

    Just my opinion, but I feel varnish was not directily applied because soaking could result in areas that would take long periods to dry. I guess an example is the edge of the top plate. I eventually learned to only varnish sparingly because too much varnish here soaked in the vertical ends and would stay tacky long after everything else is tack free. The presence of glue- fairly common knowledge, a thin coat of glue helps to scrape or sand off the vertical projections on surfaces in preparation for getting that smooth surface necessary for the top coat. A color stain in the wood- I think this is proven, not sure- they had Brazilin, easily extracted from Pernambuco bow wood, Hematoxylon from logwood, and Alkanet from a regional weed. Anyone could be applied by including in the glue coat by adding some alcohol or lime. You also want to produce an inst that is a work of art in appearance, so anything that creates dichroism such as layering of differential coats of resin would be needed. Calcium could be present in just about any of the substances. I can't think of a specific reason for adding a layer of a mineral ground other than the remains of surface preparation.
  12. yellow ground

    Mike, I didn't realize I made the smears on a coating of saturated sol lime/glue/ alcohol/ hematoxylon. That darkened the wood. I don't think that had anything to do with the color and reflectivity of the smears. The main purpose was to just show another yellow ground.
  13. yellow ground

    Hi Julian, the chemistry is beyond me regards changes of copper in the presence of more active metals for oxygen like lead, and what is in the varnish top coat. Iron, with all its valences, as a resinate doesn't change very much. Drying oils also play a part in stability of copper. I messed up as I stated in my post to Mike concerning how reflective the ground was.
  14. I posted an email earlier mentioning that rosin and copper, also with litharge makes a reflectant yellow ground. The attached is a sample of one cooked in a copper cup that also had a rim of black cupric oxide that was redissolved into the cook. The piece of wood was accidentally flipped over and tacked to a table but was still soft enough to level somewhat. Some oil can be added, 5:1 oil for better leveling I imagine. This is just to show the possibility of its use as a ground. Also, I imagine the presence of copper aided in preventing worm infestation.
  15. some recipes and a patent for violin varnish

    adding turp to a hot cook- I purposely add turp to hot varnish (ca 450 F) to drive water out. When I was making fossil copal varnishes where hotter temps are used I would use an eye dropper or a baby medicine dropper, add a drop and if it spits, add a drop and stir vigorously to prevent hot spots. Do this until a drop enters quietly, usually around 25 and then squirts can be started. I make small batches, around 15g rosin at high temps so the danger from a fire is minimal.