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UV Box - Tuto


David A.T.
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After many issues with Varnish drying I am thinking to take some time to build one UV Box.

looking for some tips on :

UV Lamp type

minimum quantity (1? or more, ?)

Lamp position (sides? Top? Bottom?)

distance to the sample

rotation speed

...

I did a search on Google and found :

https://www.andrewcarruthers.com/led-light-box/

https://maestronet.com/forum/index.php?/topic/330377-making-uv-drying-box/

 

Any up to date advices are welcome.

 

 

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11 hours ago, David A.T. said:

After many issues with Varnish drying I am thinking to take some time to build one UV Box.

looking for some tips on :

UV Lamp type

minimum quantity (1? or more, ?)

Lamp position (sides? Top? Bottom?)

distance to the sample

rotation speed

...

I did a search on Google and found :

https://www.andrewcarruthers.com/led-light-box/

https://maestronet.com/forum/index.php?/topic/330377-making-uv-drying-box/

 

Any up to date advices are welcome.

 

 

I would buy a cheap grow tent {if you can in france} and then I would go get 4 led uv black lamps...they give off just the right heat {much less than regular lamps} and use much less electricity 

the frame of the grow tent is made from metal tubes so there are plenty of ways to suspend the instrument and lights...two lamps on the floor, two lamps suspended , with the instrument hanging in the middle works well, or you can search Joe Robsons posts {using google} he has a cool way of rigging a steel garbage can to turn it into a good drying "box" 

the long and the short of it is that there are pre existing products out there that will work for the box instead of having to build and then line one with reflective material

but LED lamps in all spectrum, in this case black uv, are the way to go now, far superior type of lamp, the one I got were black lights they would sell for parties , flat panels , about 6"x 10" with a small frame that allows you to prop them up, WAY powerful and dries uv reactive finishes very well  

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some tips

 uv lights in general are much cooler operating than other lamp sources, but these ones do generate some heat, most of which seems to pool in the back of the light housing

due to this fact I suggest making sure that if you are hanging them, make sure the backs do not have direct contact with the tent, the ones that you put on the floor I suggest putting on some dinner plate or a piece of tile or something to buffer the light from the floor, as a precaution

the actual distance of the light face to the instrument can be quite close but I was using about 4-6" off the instrument

the tents have ports for fans and some vents, if you leave them open it makes it so the tent gets warm , but not hot, generally aids in drying, particularly in winter months

as I do not know these lights you have, I would test run them to make sure they dry well {varnish test scrap} as well as get an idea of how hot they get your tent, smaller tents may get too hot and may need to be fanned or to leave the zip flap open.

this I feel is the advantage over the garbage can which can get pretty hot without rigging vents

good luck hope it works out for you

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You may need more lights for a cello, to dry "quick" ,it should dry as is, but you could put a couple more on a cello, my original advice was thinking it was a violin, but I think the grow tent is the way to go for guitars and cello, or multiple violins . Seems like its working out good.

And they can be closer if you want, just depends on how much of rush you are in I suppose....close enough where the cello can spin, but not hit a light.

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I put a plate with one coat oil varnish 10 hours in it. 

But it does not seem to dry faster than a second plate I put outside.

- I can look for 2 spot more.

- the plate is in the middle at 50cm from the spot . Maybe too far . 

- would  a smalll fan in the chamber be usefull to bring more air on the surface ?

to compare,  for nail varnish they put 168watt very close to the nails. So it makes locally lot of energy.

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Unfortunately there are lots of variables, like for one, the varnish, who's or what is it? Do not expect any varnish that NEEDS uv to dry to dry fast, except modern varnish like zero'res. Conifer linseed based varnishes are notorious for being slow drying varnishes , and that as long as it dries tack free {you can place your hand on it for a minute and then pull it off with no sticking or imprinting} your doing good, hell your doing great, eventually you can make up some sherpas in the mountians story about all that dry time needed for these special varnishes and charge to watch paint dry...but in the mean time if you are getting your varnishes to dry in your dope growing tent as fast as you can get them to dry outside you're doing great! but you know some gentle air flow isn't bad

 

edit; also, keep in mind, that larger objects with more varnish, {than a small violin}in enclosed spaces , will be out gassing much more solvent and in general dry slower as oxygen crosslinking will be hampered by the solvent vapor displacing the oxygen in the local vicinity of evaporation 

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2 hours ago, David A.T. said:

I put a plate with one coat oil varnish 10 hours in it. 

But it does not seem to dry faster than a second plate I put outside.

 

Your drying chamber won't necessarily dry varnish faster than sunlight. The advantage is that you don't need to worry as much about bird poop, insects sticking to the varnish, rain, cloudy weather, high winds, the radiant heat from direct sunlight, theft, or the neighbor kids mistaking your hanging violin for a pinata.

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2 hours ago, David Burgess said:

Your drying chamber won't necessarily dry varnish faster than sunlight. The advantage is that you don't need to worry as much about bird poop, insects sticking to the varnish, rain, cloudy weather, high winds, the radiant heat from direct sunlight, theft, or the neighbor kids mistaking your hanging violin for a pinata.

Exactly the issues I had. Wind, dust, and when it requires several days/weeks it becomes a nightmare.

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  • 2 weeks later...

Quick update :

so far I am happy with the chamber.

I added a 100w black light (60+60+100=220w total) the temperature is still acceptable. I will maybe buy an other 100w ( to get 320w). Then it cost a bit when running during severals weeks ( but not much in regards to the instrument)

The driing time seems to be same as if the cello is behind a window but the big advantage is to be free from dust.

it requires 1 m square place thought. 

the chamber is cheap, lamps are not cheap. I have no idea if the small lamp as asked above work fine - their function seems to be heat production. The big led panels have ip66 Label which for sure contribute to their cost.

 

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There are a lot of different options nowadays, but I honestly think normal fluorescent UV tubes (black or not) are still the best. If they are long enough they still ensure the best light diffusion, and if the rheostats are kept outside the box they are probably still the ones that heat the inside less. They are probably also the cheapest, but I'm not sure of this if you also consider the complete electrical system to be done to bring the rheostats outside.

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1 hour ago, bobbydlobs said:

 

I'm trying to keep costs down, so I ended up buying https://www.ebay.co.uk/itm/403129598363 this 40w black light bulb. I have a car inspection light which I can hang in the grow tent and it has a protective glass encasing so hopefully it won't get too hot. 

Let us know how that type of bulb works out. Be aware though that the protective glass casing on the fixture may allow significantly less UV to reach the instrument.

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5 hours ago, Davide Sora said:

There are a lot of different options nowadays, but I honestly think normal fluorescent UV tubes (black or not) are still the best. If they are long enough they still ensure the best light diffusion, and if the rheostats are kept outside the box they are probably still the ones that heat the inside less. They are probably also the cheapest, but I'm not sure of this if you also consider the complete electrical system to be done to bring the rheostats outside.

I measured the temperature on my 4ft tubes and found that the tube and the electronics were each 10C above ambient temperature while the metal casing was at ambient.  Considering the small surface area of the electronics compared with the tube I thought it wasn't worth the effort of rewiring, and fitted a small fan. Now I run all 4 tubes with no water dish and wick and don't worry about temperature and humidity.

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56 minutes ago, Muswell said:

I measured the temperature on my 4ft tubes and found that the tube and the electronics were each 10C above ambient temperature while the metal casing was at ambient.  Considering the small surface area of the electronics compared with the tube I thought it wasn't worth the effort of rewiring, and fitted a small fan. Now I run all 4 tubes with no water dish and wick and don't worry about temperature and humidity.

Yes, but you had to do the fan wiring...:)

Just kidding, I suppose with the fan it is perfectly fine, but I don't have fans in my box.

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