Urban Luthier

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Posts posted by Urban Luthier

  1. On 8/6/2019 at 7:31 PM, Michael_Molnar said:

    KOH and K2CO3. So, I do not do any UV tanning.


    Hi Michael,

    Sorry for the very naive question but is this K2CO3 the same stuff we use to precipitate lake pigments? i.e. potassium carbonate?

    any adverse affects of applying such an alkaline substance on wood?

    interesting stuff, I enjoy your bench thread very much. 



  2. 3 hours ago, StanY said:

    They're not untouched but I thought about this thread yesterday when we saw the Medici tenore viola (and cello) at the Accademia in Florence. 

    The tenor viola is likely the most 'untouched' strad. teh S+Z book on the Tuscan Medici violin has an exellent survey of the medici set

  3. I was at the ashmolean just two days ago and saw the messiah. I really don't know why theses threads crop up every couple of years. Just from visual inspection alone it would be difficult to disput its authenticity. Plus all the scientific research...

    if you haven't seeing it, it is worth the trip to Oxford. 

  4. On July 31, 2019 at 3:01 PM, Michael_Molnar said:

    From my workbench thread: "Look at the STRAD poster and other good photos of the Stradivari Viotti. I recall that the lower treble back has some burnt appearance, not much, but it's there. This tells me that Stradivari went a little beyond the infusion limit."

    Sometimes makers try to deify Stradivari for his varnish, but it has flaws just as anything made be a mortal. Nevertheless, his workmanship is excellent.

    One thing to note about the Viotti is the figure on the back is extremely deep. I do agree with Mike there appeares to be burn in. When you look at the section Mike refers to from an angle, however you still get a rich chatoyance affect. To the naked eye It apears that the darkness in the flame comes from clear varnish that soaked in through the ground rather than a coulored stain. Some of the B&G photos show more than what one can observe with the naked eye. It is a remarkable instrument I must have spent an hour looking at it a the RAM when I was last in London. The red colour appears to be in the varnish, thin and intense and laid down over the ground/varnish.

  5. On July 28, 2019 at 4:36 PM, scordatura said:

    The origin of this horse s**t and urine is Koen Padding and B&G? Is there a historical written source that they got this approach from? I have the Padding book but am out of town.

    Roubo is the source of thr recipe.  As noted above, a translation of the recipe is in Roger's bass book. Although he didn't say definitively, Roger did suggest Padding's primer was along the same lines.

  6. On 7/9/2019 at 5:07 AM, nathan slobodkin said:

    Just looking at this thread again. I had one of my cellos show up in my shop for appraisal that had a two piece, quartered black willow back and quartered ribs.15 years old, no deformation or other issues and now on the list of my better instruments.

    Hopfully it will stand the test of time like the Castelbarco Strad cello. Over 300 years old with not a single crack in the ribs!


  7. 15 hours ago, nathan slobodkin said:

    As has been discussed before there are many species of the Salix and Populus families sold commercially as Poplar. I have seen cotton wood from Western Canada sold for instruments and would definitely not use it myself while tulip polar is actually of the magnolia family and in my experience is the densest and heaviest of all the commercial "poplars".

    I suspect the species accounts for the difference between your two sets of ribs not the sawing.

    Any idea how to identify a pice of poplar by looking at it? I'm curious about the piece I posted above. As for the ribs, I may have enough thickness in the wedge for the ribs, if not I'll look for some nice beech.

  8. On 7/9/2019 at 9:27 AM, Conor Russell said:

    Here's a  poplar  back fairly  well  quartered, with the faults I have seen from  time  to time.  I'm sure a less deeply flamed piece would be fine, although  I  just made a cello with planner ribs, one of which cracked straight  through in the bending. These flames really can send  the grain plunging straight  down. I can push the corner  of my business  card a full 8mm in to these shakes.


    Geez Conor that's nuts. Nice for a flat piece of furniture but I couldn't imagine bending or carving this stuff. The poplar I have (pictured above) is halfway between quarter and slab - the light figure has a sort of quilted look. it reminds me a little of the cello you posted awhile back. 


  9. 3 hours ago, Anthony Panke said:

    Which one? 

    I bought a small veritas plane with a (double) convex sole, works okimage.thumb.jpg.24a472aec723c95881707493fe7745a1.jpg

    but my favourite by far is the ibex plane, which cuts much more smoothly. Imo the veritas plane is too round, so only good for very wide, deep fluting. image.thumb.jpg.3c09cd15c72c4867b1a866dde15e82a7.jpg

    I pretty much only use the ibex finger plane and a block plane.

    i agree I have this one as well and don't use it at all

  10. One of the biggest challenges of jointing is getting both edges to mate perfectly. If you do them one at a time, edge up in a vice, there is a tendency to twist to the right on the start of the stroke and twist to the left on the end of the stroke (if you are right handed that is).

    If you are having trouble with the centre joint, one trick is to plane both edges together. That way any irregularity or twist will be canceled out when you place the two edges together for gluing. Joiners have used this workflow for for centuries! 

    other thing to note is to ensure you plane is sharp and the blade is straight (i.e. no camber).

    Once you get it perfect, glue it right away! With a bit of practice it is possible to get a perfect joint. I routinely have to use a 5 x loupe on spruce tops to see where my centre join is.


  11. I know this is an old thread but i was wondering if anyone has made a cello off of Sacconi's reconstruction of the cello b-form as posted above. Based on Joe's comments, it appears to differ slightly from Roger's  Davidov drawing (lower part of the centre bouts are lower in the Davidov)

  12. 6 hours ago, jezzupe said:

    boy I'm sure glad I'm not all caught up in this here "measuring stuff" I have a 1-6 with "high" above the 6, so, I turn it onto "high" for about 2 min, then turn it down to 6 then down to 5, and then turn it down between 4 and 5 and whatever that is, it just right! geez next thing you know you guys will be asking questions about rulers and measuring cup's :lol:...

    for those of us who measured the temp i don't thing it is about laser precision here -- most of us did what you did - test a bunch of different  temperatures  based on personal workflow to find out how hot you can bend without burning. Then mark the position on the iron and be done with it. in my case I was simply curious to know if the surface temp of my iron matched what's printed on the dial. And in my case it is pretty close.