This blog explores my experience with making an ultraviolet (UV) box, chamber, cabinet (whatever you want to call it) for tanning a violin and curing its varnish. In the beginning, I didn’t really know what to choose (especially the lighting), so hopefully this blog may be of use to other luthiers.
I had a few ideas in mind for what my box could be:
- One option was to buy modify a popup tent for growing particular plants. Many of these on eBay and Amazon have ventilation and white-mylar linings, which my friend pointed out later to me, is one of the most optically-reflective materials
- Another was to buy a cabinet, and this would definitely be more solid than a tent, which is always reassuring. A cabinet’s walls would be thick enough to place lighting anywhere and make other necessary modifications.
- Some makers use galvanised-steel dustbins, which have the benefits of portability, and have a pretty reflective interiors. However, I wasn’t too keen on this because it seemed like modifications would be difficult to perform, due to it’s size and shape.
I’m sure there are other options but in the end I bought a simple cabinet from Argos (a retail chain in the UK) with the approximate dimensions of 70x85x35cm. The dimensions are a bit large but this allows me to be quite versatile with what I can do with the interior, which will be discussed later.
The cabinet was assembled and then I proceeded to deal with the components.
It’s pretty well known that fluorescent lights can give off heat; I didn’t want to risk not having any cooling so I bought a small computer-style fan which could be mounted to the inside. The fan was bought from Amazon for £8, which is usb connected and has 3-speeds. It’s quite pragmatic.
Temperature and humidity:
So as mentioned, the UV lights usually cause a rise in temperature and cause a decrease in humidity so I wanted to monitor these levels. The best solution I could think of was to buy a digital thermometer and hygrometer which takes readings from an external gauge and displays the readings. The display can be conveniently sat on-top of the cabinet.
As for the actual humidity, I could just fill a small glass with water and leave it inside, which will keep the interior from becoming too dry.
Given its popularity with violinmakers, I decided to use fluorescent UV bulbs (as opposed to LEDs) but my issue was not knowing which to use.
You get bulbs which give UVA, B, C, and often a mix of these. From the experience of other makers, UVB seems to be the most overall appropriate type of light to use. I’ve been told that UVC should NOT be used as it produces the most gases, many of which are caustic and dangerous to humans.
As a 19 year old, who had minimal knowledge about fluorescent lighting, I kept things simple by following a lighting system intended for reptile keepers. I bought 4x 20w T8 desert grade UVB tubes (highest strength), and two ExoTerra dual lighting units.
The rest of the items bought were just various screws, nails, and a good-quality 4-socket extension lead. The next steps were to make holes for ventilation and cables to be passed into the interior. This was straightforward enough.
Lining the interior:
This was a fun stage. I debated between using tinfoil, mirror card or chrome spray paint, and ended up using mirror card because it’s relatively cheap and would give a neater interior than tin-foil.
I bought 8 A3 sheets of mirror card, and trimmed and joined them accordingly; they were cut to accomodate the hinges, ventilation and cable holes. The card was primarily lined to the interior using double sided tape, which works absolutely fine. The various screws for components would also secure them.
Finally, the step was to attach the ballasts to the outside (one on each side), the UVB tubes and other components to the interior, and a hanging wire for a violin.
Some things to note: Even though these lights appear white, they give off an intense amount of UVB which in prolonged exposure can cause blindness and cataracts, among other health issues. It’s advised that you take the necessary precautions to protect yourself from this.
This UV box works very well with tanning and also blends with the decor of my workshop. Double win!
Get the look!
- Exoterra Lighting units
- T8 UVB tubes
- USB fan – a bit small but gives a regulated temperature of 24-25 degrees
- Belkin 4-socket power lead
- A3 mirror card and double sided tape – I bought mine from a local art shop
- Thermometer Hygrometer
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