UV-A bulbs

[finnfinnviolin]

I have access to some medical grade Phillips uv-a bulbs, what are people's thoughts on how these cure varnish/ tan? 

 

Thanks

[Michael_Molnar]

Do a search at the top right of this page. There you will find lots of great information. 

I you sure they are UV-A? "Medical grade" makes me wonder whether they are A or C which is dangerous.

[Jim Bress]

Here's a quote from Jeffery Holmes quoting Koen Padding.  I save this qoute because I find it valuable and for some unexplained reason I can't seem to keep this relatively simple information (A, B, and C) in the right order.  Somewhat dated, but I think it is still relevant.

Jeffrey Holmes:

I received the following e-mail message from Koen Padding and am posting it on his behalf:


Hello Jeffrey
While browsing the maestronet I saw some entries on drying cabinets. Because all types of lights (UVA,UVB and UVC) are potentially dangerous and the entries seem very confused about the subject I thought I should respond but am not a member so my response is to you. UVA, B, and C are of decreasing wave length and increasing hazard in this order. UVA is similar to natural sunlight and all that is needed to dry oil varnishes, but it is already not wise to look straight at it with unprotected eyes. UVB often referred to as "blacklight" is definately ruinous to your eyesight and can e.g. be used for sterilization of hospital rooms. That’s how highly energetic these short wavelengths are. This is important because one of your entrants actually advises to use it probably because he cannot see any light when looking at it and does not realize that a blacklight is even more UltraViolet than UVA. A drying cabinet is best and safest made with about 250 Watts/m3 of ordinary Suntanning Tubelights. E.g. Phillips UVA  colour Nr. 3A The 120cm long tubes are 80 Watts so 4 of them in a cheap double doored wardrobe 180 X 60 X 120 cm will make a good Cello sized cabinet. Replace the top by mosquito wire against overheating and bugs. Line the inside with Aluminum foil Don't run the cabinet in your workshop or house, All UV lights produce Ozone and through that some Nitrous monoxide (UVB and C even more so) but have it in the garage or a well ventilated room.  Don't use blacklights because:

-They are too intense and dry the varnish too fast.
- The gasses they produce are bad for varnish and although   the Nitrous monoxide will colour wood nicely, in the long   run it is destructive to it. This is because it promotes the formation of "free radicals" in the wood which spead up its ageing process in an uncontrollable way.  If you ask for UVC at your local shop you'll probably end up on the FBI potential terrorists list.
 
Sorry for the length of my reply
regards
Koen Padding

[David Burgess]

BLB bulbs (the blue colored glow-in-the-dark "party"  bulbs) are pretty cheap at the big home improvement chain stores, and work fine for drying varnish.

https://www.lowes.com/pd/GE-40-Watt-0K-Black-Linear-Fluorescent-Tube-Light-Bulb-Common-48-in-Actual-48-in/3400504

[finnfinnviolin]

4 hours ago, Jim Bress said:

Here's a quote from Jeffery Holmes quoting Koen Padding.  I save this qoute because I find it valuable and for some unexplained reason I can't seem to keep this relatively simple information (A, B, and C) in the right order.  Somewhat dated, but I think it is still relevant.

Jeffrey Holmes:

 

I received the following e-mail message from Koen Padding and am posting it on his behalf:


Hello Jeffrey
While browsing the maestronet I saw some entries on drying cabinets. Because all types of lights (UVA,UVB and UVC) are potentially dangerous and the entries seem very confused about the subject I thought I should respond but am not a member so my response is to you. UVA, B, and C are of decreasing wave length and increasing hazard in this order. UVA is similar to natural sunlight and all that is needed to dry oil varnishes, but it is already not wise to look straight at it with unprotected eyes. UVB often referred to as "blacklight" is definately ruinous to your eyesight and can e.g. be used for sterilization of hospital rooms. That’s how highly energetic these short wavelengths are. This is important because one of your entrants actually advises to use it probably because he cannot see any light when looking at it and does not realize that a blacklight is even more UltraViolet than UVA. A drying cabinet is best and safest made with about 250 Watts/m3 of ordinary Suntanning Tubelights. E.g. Phillips UVA  colour Nr. 3A The 120cm long tubes are 80 Watts so 4 of them in a cheap double doored wardrobe 180 X 60 X 120 cm will make a good Cello sized cabinet. Replace the top by mosquito wire against overheating and bugs. Line the inside with Aluminum foil Don't run the cabinet in your workshop or house, All UV lights produce Ozone and through that some Nitrous monoxide (UVB and C even more so) but have it in the garage or a well ventilated room.  Don't use blacklights because:

 

-They are too intense and dry the varnish too fast.
- The gasses they produce are bad for varnish and although   the Nitrous monoxide will colour wood nicely, in the long   run it is destructive to it. This is because it promotes the formation of "free radicals" in the wood which spead up its ageing process in an uncontrollable way.  If you ask for UVC at your local shop you'll probably end up on the FBI potential terrorists list.
 
Sorry for the length of my reply
regards
Koen Padding

 

Thank you Jim for sharing the Koen Padding letter...

 

I had the contact of a lady who was selling sun bed tubes for £2 each a few weeks ago, I think I will just go for that... 

[Don Noon]

9 hours ago, finnliengaard said:

I had the contact of a lady who was selling sun bed tubes for £2 each a few weeks ago, I think I will just go for that... 

Cautions:  they are often very high wattage and very short life; commercial users may replace them on a regular basis shortly before they burn out.  Beware of getting used ones... they might work, but not for long.

[Davide Sora]

In the letter of Koen Padding I think he does a bit of confusion when he says :

"UVB often referred to as "blacklight" is definately ruinous to your eyesight and can e.g. be used for sterilization of hospital rooms."

To my knowledge, the Blacklight are narrowband UV-A (370 nm) and not UV-B, and the latter are not germicides but are UV-C ones used for sterilization.

This does not mean that Blacklight (and all UV radiations) are healthy, precautions against harmfulness of UV should not be taken lightly.

[David Burgess]

2 hours ago, Davide Sora said:

 

In the letter of Koen Padding I think he does a bit of confusion when he says :

"UVB often referred to as "blacklight" is definately ruinous to your eyesight and can e.g. be used for sterilization of hospital rooms."

 

To my knowledge, the Blacklight are narrowband UV-A (370 nm) and not UV-B, and the latter are not germicides but are UV-C ones used for sterilization. These are the most dangerous.

 

Right, Padding was off on a few things. And as you said, the "germicidal" lamps used for sterilization are UVC.

[Jim Bress]

I guess I need to edit my notes.

[Jim Bress]

A bit confusing.  The vernacular suggests BLB is black light blue bulb which is a UV-A bulb with a blue filter blocking out the rest of the visible light spectrum.  Whereas a black light bulb is a higher energy bulb with no filter.  I'm not clear if all black light bulbs go into the UV-B spectrum, but there is no filter.  Here's a couple of rapid readings, so maybe I missed some key details.  However it is clear that there is a difference between Black light bulbs (BL) and blacklight blue bulbs (BLB).

http://www.lightingsupply.com/articles/black-lights-blacklight-blue-bulbs/

https://en.wikipedia.org/wiki/Blacklight

[Urban Luthier]

21 hours ago, David Burgess said:

BLB bulbs (the blue colored glow-in-the-dark "party"  bulbs) are pretty cheap at the big home improvement chain stores, and work fine for drying varnish.

https://www.lowes.com/pd/GE-40-Watt-0K-Black-Linear-Fluorescent-Tube-Light-Bulb-Common-48-in-Actual-48-in/3400504

I use these as well but smaller versions. They appear to give off less heat than the equivalent size UVA tanning bulbs. Has anyone else experienced this?

[ctanzio]

21 hours ago, David Burgess said:

BLB bulbs (the blue colored glow-in-the-dark "party"  bulbs) are pretty cheap at the big home improvement chain stores, and work fine for drying varnish.

David, this is a fantastic bit of advice for people wanting to try out oil varnish projects. Thanks.

Do you have anything you can add on the total wattage to use for say a violin cabinet, and the hours of exposure you prefer?

[Don Noon]

26 minutes ago, Jim Bress said:

A bit confusing.  The vernacular suggests BLB is black light blue bulb which is a UV-A bulb with a blue filter blocking out the rest of the visible light spectrum.  Whereas a black light bulb is a higher energy bulb with no filter.

It seems fairly straightforward to me, at least in the normal commercially available bulbs I use.  I can get BLB and BL versions of the tubes I use, and they are exactly the same except that the one with the extra B has the dark filter that removes the visible part of the light.  I have used both, but prefer the one without the filter so I can tell tell easily if it's burned out.  

I haven't researched much beyond that, but I suspect that tanning bulbs are amped-up versions of BL so you can get a tan in 20 minutes, and not 2 days.

Regarding power, my cabinet has 4 x 20 watt bulbs in it.  Drying time is highly dependent on the properties of the varnish, varying from 3 hours to 1 day.  Wood tanning takes a lot longer, several days, although I don't do that any more.

[JohnCockburn]

I wish no disrespect to Mr Padding's memory, or to his important contribution to our field. But what he writes about UV sources, ozone generation etc is mostly wrong.

[JohnCockburn]

17 minutes ago, Don Noon said:

 

I haven't researched much beyond that, but I suspect that tanning bulbs are amped-up versions of BL so you can get a tan in 20 minutes, and not 2 days.

 

tanning tubes normally have more UVB emission than BLs

[Dwight Brown]

Are LED strips available and cheap enough in the proper wavelengths?  It might solve some over heating and other problems.  I really do not know.  I think there has been some discussion.

 

DLB

[Rich]

Old Wood 1700 has recommended a bulb.  Go to  the oldwood1700.com  site and click on Ultraviolet Lamp.  It shows a drawing of a light box along with their recommended bulb.  The bulb is labeled  "Actinic BL TL-D 18w/10

 

I use something similar.