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robertdo

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Everything posted by robertdo

  1. You can see there variations for making madder lakes. So yes, some people will first dissolve alizarin into the potash and then precipitate with alum, while others will first extract alizarin with alum and then precipitate with potash (or not). You can try these ways and decide if there is ultimately a real difference in one way or another.
  2. to be honest I don't really think it takes that much time (neither it is complicated) to make a madder lake, especially if you start with root powder. What more simple do you want than soaking the roots in potash, filter, precipitate with alum and wash?
  3. Maybe not. Maybe there was no lime treatment in the old time varnish either.
  4. that would not be easy in 100% ethanol solution.
  5. Although there might be some variations in the hue in various brands, madder lake is pretty cheap (of course some specialist distributors like Kremer will charge more than others). I don't think that the price is the main reason to make it yourself. It's just nice to try once to see.
  6. One thing must be kept im mind though (and it was raised in one of the comments in the website I visited when I saw this article) is that even though the law has passed, you might well still be asked for some justifications if you go through the green door. Because I recently took the plane with my contact lenses liquid in my handbag. It is a 250 ml bottle. With the ancient law I would have not been able to take it, even in a plastic bag (less than 100ml). But in April 2013 the law was changed in Europe and this liquid volume restriction was abolished. So when I asked the custom officer why he would not allow me to take it, he said the law was different in UK (which was a lie). Eventually, since the bottle was more than half empty he let me go with it. .
  7. Funny, on wikipedia I read that linoleum is made by pouring polymerised linseed oil on top of vertical pieces of linen (consecutive layers are added until a 2-3 cm thick polymerised linseed oil is obtained) the linseed oil film is then recovered, cut into piece and melted with copal and colophony. this mix is then let to dry for weeks, they call it a cement. After it is dry this cement is mixed with cork and wood sawdust. So in effect linoleum is a varnish mixed with cork and wood while I always thought it was simply linseed oil polymerised with cork.
  8. I was even on the impression that the heating step was mosly there to get the most of the madder from chopped roots. If you already have powder, you don't really need to go through that step. You can simply put the powder in the potash (the color will instantly turn ruby red) and leave it like this for as long as you wish without heating. then when you have time you can go on with the process (filtering the mix, adding the alum to precipitate, and washing the madder lake.)
  9. I don't know what kind of bonds oil and colophony make (or if they make bond at all) but no doubt there are possibilities given the formulae of these 2 chemicals (it needs not to be covalent bonds though). the other clue could be the fact that upon heating oil and colophony you can reach a "firm pill" stage that doesn't exist for quite a while after oil and colophony had been thoroughly mixed at the begining of the heating process. A simple dilution oil/colophony seems difficult to reconcile with this.
  10. I, for my part, always thought the G string had only been invented so that Paganini can be thrown in jail, break the 3 other strings, and still manage to play...
  11. It would be great if the stick was not making any difference at all. Everybody would play with aluminium bow, very resistant, almost unbreakable, it would save Pernambuco, and save lots of money...
  12. Sorry, Omobono, my mistake. I was referring to the other picture, front of NB holding the violin normally. On the picture you are talking about there is no doubt the F-hole was cut the way it is now.
  13. It looks to me that the treble lower wing of the violin she is holding is simply broken, which gives the impression of being designed the way it is. the other F hole looks like a "generic one". Why would a maker cut the 2 f-holes differently?
  14. Yes, I was surprised because the violin on the picture obviously doesn't look at all like the ones made by the Guarnerius family.
  15. And I believe even in good restaurant, most people would not pay too much attention to the music, even live. Also given what we heard aboutall these blind tests....
  16. Yes but what I meant is if you look the end of these clamps, they would not touch the lining and would likely prevent the clamp from really pressing down much of the linings (assuming we are talking about a standard 12mm inside mold which leaves about 9mm of free ribs for the lining). When I made mine with wood cloth pegs I did cut the end of them like many people do, I believe
  17. I think the way they are built makes it difficult to use them for the linings .
  18. this could look like parallele marks from some kind of toothed planed?
  19. I know it was already discussed, but as someone pointed out if they are the result of clamping the marks are located very much inside the plate. And I was under the impression that the purfling and channeling was done after the plates had been glued to the garland?
  20. the argument about the iron pot is valid of course (induction works this way) but most of the "cooks" know that when they use for example stone or all ceramique pots (very good, nothing attaches etc...) and induction plate, all they have to do is to put a metal plate underneath the pot.
  21. Wood can get "fossilized" or "petrified" itself quite quickly but this requires some special conditions. For example when I was a kid my father was still working in an iron mine. the surrounding was very "calcareous" and some miners (including my father) used to leave some pieces of crumpled absorbant paper just under some "stalactites" It would not take too long before they get a superb work of art that I and few of my friends would proudly bring in class to display. But for a violin wood to petrify would take ages if simply stored correctly in a dry environment.
  22. there is a small paragraph on "craquelure on cello's varnish" there. No real explanation but a hint .
  23. I don't know anything about the convention associated with "ex", but wouldn't there have been many more ex Heifetz, ex Menuhin, ex Oistrakh, ex Milstein...
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