Violin Forum/Message Board

williamwalsman

I have a drying cabinet like many other makers that makes use of uvb bulbs to hasten drying time for oil varnish on my new violins. It is located in an outdoor, unheated shed. Normally I varnish in the spring where temperatures inside the cabinet while using the bulbs is in the 70- 80 degree range. I have two violins ready to varnish now but have noticed temperature inside the cabinet with lights on only getting up into the high 40s range. I would like to bring the cabinet into my heated basement but am worried about chemical/ ozone related after effects from the drying process. I understand and take precautions related to risks to eyes, etc. but is anyone aware of these other air borne risks. If there are significant risks how much ventilation is needed. Note: My cabinet uses up to eight, 20 watt uvb, not uva bulbs which are less dangerous. If the cabinet needs to stay outdoors what would be a safe minimum temperature to expose the violins to? Thanks for any suggestions. Bill[/u][/b]

kjb · Super Member Joined: 06 Feb 2013 Posts: 385

normal room temps should be fine, there are probably temps that are the optimum for drying also humidity is important , an electric heater could keep it within 20F of the optimum, with a fairly cheap thermostat.

this is just my opinion I would wait for others advice before proceeding.

williamwalsman

After posting the earlier questions about uv drying cabinets I came across a paper I read by the late Koen Padding. The paper was entitled "Use of ultraviolet light sources in lutherie", published in VSA Papers Summer2007, vol. XXI, no.1. I read this a couple years ago, forgot most of it except the part of how dangerous these things can be if used wrong. A side note in this article is his belief that tanning violins prior to varnishing is detrimental to the wood. Again I'm throwing this out there for any of you who have read this, knew Koen, or have strong opinions about his concern on potential dangers involved in the use of drying cabinets. Bill

Michael Darnton · Posted: Mon Dec 23, 2013 8:53 pm Post subject:

Given that most violin makers are using lamps very similar to tanning beds, and even the same ones, I think if there's a ozone problem we'd have a trail of dead tanners to demonstrate it. I'd be more concerned about the solvents in the varnish, relatively, but I don't think you have to be concerned about that either, with just a bit of ventilation at the start of the cycle--most of it is gone in the first hour or so.
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williamwalsman

Michael, thanks for the input. I tend to agree with you though the tanners aren't on a bed with a freshly varnished violin. And according to Koen Padding it is the ozone/ nitrous oxygen, by products of the accelerated chemical reaction between the uv lamps and the varnish, that are the danger. After rereading the article for the fourth or fifth time I get the sense he might be exaggerating the potential risks but he certainly seemed to know his chemistry. Michael, did you know Padding? He apparently was well known for his varnish technique/ process. Odd that he was against tanning violins when that seems to be universally accepted among early and modern makers alike. I've read and reread your work on finishing violins many times. Its been very helpful! Other than the white showing through if the new violin is chipped, what would be the main detriment to not tanning prior to varnishing?[/u]

FiddleDoug · Member Joined: 08 Sep 2007 Posts: 227 Location: Hilton, NY

There are a couple of problems with trying to dry varnish in the cold. First is that the vapor pressure of the solvent used will be MUCH lower, and the drying time MUCH longer. Second is that the drying reaction under the lights is a chemical reaction. The reaction rate goes down by a factor of two, for every 10 deg. C drop. That would mean that it would take about 4 times as long at 40 deg F as at 80 deg. If you're really worried about it, put a small ventilation fan on it, and exhaust through a tube out a vent or window for a few hours until the varnish is mostly dry.
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Michael Darnton