Hello all, I'm new to the forum and have come here specifically to ask you folks for some help and advice in building a from-scratch light fixture. I am a silversmith/gunsmith/metalsmith and am getting into a new (to me) method of electro-etching called “Photoresist etching”, which involves using special UV-treated coating to transfer images onto metal, which is  subsequently etched using conventional electro-etching methods.  This process involves exposing the piece to UV light in a controllable manner- and I have not been able to find any UV light that would suit my specific need, so I decided to build one.
 
I am not an electrician, but I have built an oven for baking thermal-cured metal finishes using a filing cabinet, the guts of a toaster oven, and a PID thermostatic controlling device that would fool anyone into thinking it was a commercially produced professional appliance.  So- I figured I could handle building a light box.

I found some UV light bulbs that I thought would be appropriate for my task, they are F10T8/BLB BA15D 13” T8 florescent bulbs, 130V They are 10W each and produce light in the 360nm range.  I bought 5 for cheap.

I bought 10 T8 G13 Florescent light holder sockets- (one for each side of my 5 bulbs, but I've conceded that a 4 bulb light fixture will be what I'll build.) What does the G13 designation mean?

I knew (just) enough to realize that a florescent light fixture needs a ballast, so I purchased a:
GE 4 Lamps T8 Fluorescent Dimming Ballast, 120-277V, GE432MVPSN-V03W, NEW

I picked it because it is designed to run up to 4 bulbs, I thought I (mistakenly?) understood it was intended for 10W bulbs, and can be used with a dimmer control so that I can fine tune the voltage and ultimately set it at the proper brightness and duration needed to perfect my etching process.

Now that I have purchased these items and they are in the mail to me, I'm starting to wonder if I'm in over my head and I'm getting the feeling that I need more knowledge to do this safely.

My first question is this: Can I run  (4x)F10T8 bulbs on a ballast that was designed to run (4x) F32T8 or (4x) F28T8 bulbs? If the answer is “no”, is it a catastrophic “NO that is dangerous!”, or the type of “no” that has to do with bulb life or optimized light output, or just not coming on? If the answer is yes, could I run five F10T8’s with this ballast? My light will be run about an hour at a time and just on occasions, so I'm less concerned with maximizing my bulb's lifespan. I'm also not concerned with “preheating” in the context of needing the bulb to light up immediately when I hit the switch as one would need with home lighting fixture, but am I misunderstanding the concept and context of “preheating”?  I understand that a ballast is needed to bring the bulb from an off/resting condition to an on/lit condition  by somehow storing or transforming 110V electricity but not sure how or in what context that works, or what the safety issues are if they are mismatched with a bulbs. Not that I'm aching to try it, but what happens when you wire the bulbs without a ballast directly to 110V AC?

What does the F10 versus F32 distinction relate to? Wattage?  Length of bulb? I've seen discussions on this forum of running an F32 bulb with an F17 ballast, but wondering what problems arise from running an F10 with an F32 ballast?  I also know that there is a big difference between a T8 and a T5 ballast/bulb, not that it applies in my case, but could someone explain that difference to me?
If there are any other issues or problems that you guys can see arise with my building of this  (4-5x) 13” 10W UV light fixture, please chime in. For example- I plan on creating a fixture box using mirrors or highly reflective surfaces that allows me to expose UV directly to all the surfaces of 3-d objects,  DO these UV bulbs create excessive heat that would require me to utilize a ventilating fan if they are in an enclosed box? What kind of fusing would you suggest I use? Etc.
Thanks in advance for any input.

Hello, and welcome to the site! I'll try and directly answer your questions as I read them...

To begin with, you've purchased blacklight blue lamps. These lamps only produce long-wave UV light, which is used for stuff like making fluorescent materials glow. When I read of this etching process you speak of, I would assume it requires short-wave UV light, in which case you'll have to buy lamps provide that light, probably germicidal lamps. But I don't know - you'll have to find out for yourself if you need short-wave UV.

You chose an extremely uncommon size of lamp - the F10T8 isn't used anywhere, and I don't think ballasts for them are commonly available. You did buy the right kind of sockets. G13 is just the designation for the type of socket; it's also known as medium bi-pin.

While the ballast you bought is indeed far from the right type, it should actually work just fine. I won't bother you with the theory regarding why, but the lamps should run just fine, and so should the ballast. You're only gonna fit four lamps on it, though - a ballast meant to run four lamps won't run five. Don't worry about "preheat" or what it means. This ballast is actually what's called rapid start, but you don't need to know that or what it means.

If you wired a lamp directly to 120V, likely nothing would happen when you apply power, because 120V isn't enough to start a lamp without preheating. If you were to preheat the bulb, though, the cathodes (tungsten wires at each end of the lamp) would immediately self-destruct (with a bright flash of light), and the lamp would become useless.

In the case of the F10T8 and the F32T8, the numbers indeed mean 10 watts and 32 watts, respectively. The reason some improper lamp-ballast combinations work well (like an F10T8 or F17T8 running on an F32T8 ballast) is because those lamps all require the same amount of current, and so, depending on the type of ballast, get the right amount of power on each other's ballasts. The reason is because the power is dictated not only by current, but by the lamp's arc voltage. Those three lamps all have different arc voltages. I'll leave you with that.

With that said, the reason T5 lamps and T8 lamps are practically forbidden from running on each other's ballasts is because they require completely different amounts of current.

I would say you have nothing to worry about with regards to heat. Neither lamps or ballast will generate enough to be a problem.

OK thanks so much for your help. As far as the bulbs, I recognized when I was looking for bulbs- that there were "blacklight" bulbs which are basically just for aesthetics,  and actual "UV" emitting bulbs (the type that can give you a sunburn if you're not careful). I thought I'd found the proper ones as they claimed to produce light in 360nm range, which I'd understood 350-400nm was what I was looking for my process. I think, and may be wrong, that the germicidal lamps are in an even lower range than I need and are a more specialized and costly lamp. I think most folks that do photoresist use the same type of UV lights that they use to cure fingernails at the manicure shops- I was hoping to create a light that is bigger then those small units. either way, I'll do some more research.

I may have to go back to the drawing board, with some new bulbs, and thus a new Ballast. If I do, rest assured, I'll be getting advice here IN ADVANCE this time!.

Thanks again.

 

In my experuience  with photo litography (in my case etching a "pronted circuit board" pattern), the best results were with plain sun. The exposure is not so fast, but compare to other methods (except some proffessional equipment) highly repeatable. But it obviously works only on a clear, sunny day.

Otherwise for sharp images, mainly with noit really flat surface, you will need a point UV source, there the long germicidal tubes do not work so well.

What ie very frequently used by hobyist is a MV lamp with the outer bulb removed (that normally block the UV you need). For small objects (the home made circuit board sizes are usually small) the bulb is placed on the top of a "tower" PC case, the things to be exposed are then at the bottom. Usually the box is placed upside down first, so the "CD" drive openings could make the access port to insert the workpiece.
But for these, to ger repeatable results, you have to first burn the lamp for at least ~100hours when new, then remove the outer and install in the box. So your arrangement should provide sufficient shielding. And as the exposed lamp frame (normally covered by the outer bulb) is connected to the live circuit, that box should provide a barrier preventing anyone to touch the lamp when connected tyo mains.
The ebest way for exposure control is the time, controlled by a "shutter" plate (so when the light is suppoised to be OFF, the shutter block the light, but the lamp remains ON - waiting to replace the workpiece).

Then before each exposure, the lamp has to be turned ON and running at least 15minutes to stabilize Before that the output is highly temperamental and unpredictable, so not usable for the lito process, you really have to let the lamp stabilize. The work then has to be inserted when the bulb is rubnning. Therefore it could be better to forst prepare a batch of multiple workpieces, so you start the lamp only once to process more items. The exposure time would be then in minutes.

As the arctube is exposed to the oxygen, do not expect longer lamp life than few 100 hours, so stock up replacememt bulbs when they are still available...
For longer life it would be better to use 1 step highger lamp wattage than the ballast rating, e.g. 175W lamp on a 100W ballast, or 250W lamp on a 175W ballast. The lamps would emit less of the visible light than the rated lamp on the same ballast, but the UV would be about the same
For lower wattages, a 100W lamp on a 100W ballast may still work, but expect the shorter life...
As the lamp reduces it's output over time, I would advise to always put there a refference pattern (narrow triangles, multiple pieces in different distances, so you can get the estimate, what reserve is there...), so you may observe, when the exposure become insufficient and adjust the exposure time accordingly. If it become too long, replace the bulb...


For the ballast: The 1foot F10T8 are designed for 0.25A, so you may actually operate 3 lamps in series on a single lamp F32T8 instant start ballast (the type with single wire to each lamp end in the original circuit). So the most common 2 lamp ballast will then serve 6 F10T8 lamps.
But the problem with the BLB not activating the photoresist does remain...

Medved, the printing/etching of circuit boards you describe, is chemically the same process i'm working with, but the scale does not work for me. I know that the altering MV lamps you describe is not something I want to get into, , I really just want a UV light like those I've seen others use for this process, only much larger- and able to create an etching on  something more than 3" x 3" circuit board. My wife uses a similar process requiring specialized equipment in screen printing- transferring images onto screens that can then be used to apply ink to t-shirts and the like- I can't use her ( single plane-2Dimensional)light either to create the UV environment I need, But I'm confident I can build one that lets me expose any 3-d object smaller than a cinder block to UV light in a controlled manner

I have come to realize that I was a bit bamboozled when purchasing these BLB bulbs, What I'm really needing is F10T8- GL bulbs that I thought I was getting (the germicidal bulbs as someone pointed out), so I'm going to go forward building the device as I've envisioned. and purchase the correct bulbs down the road (like my next paycheck). I'll post up some photos here as I progress.

It's my understanding (from what you are saying) that my 4x-F32T8 Ballast could be used to run (UP TO?) 4x3= 12 F10T8 bulbs, if wired 4 x (3 in a series), is there any difference in the F10T8/BLB and the F10T8/GL in terms of the 0.25A you described?

thanks so much for your help with this.

If the G10T8 (what would be the correct notation of the germicidal lamps; The "F" mean fluorescent, while on the germicidal there is no phosphor...) is really the same electrical spec as the 1' F10T8, it will work.

But the possibility to connect lamps in series is really limited to the instant start ballast only and that for sure won't be dimmable. So double check, what type of ballast you are using (you may post it's wiring diagram, from that I can confirm if it will work or not).

With the MV: If your object is large, then I would install the lamp (probably of a higher wattage then) with a shielding cover, what could be opened remotely (by some cord or so) from another room. Then when the cover is closed, let the lamp stabilize, arrange the workpiece and then leave the room. Then open the cover for the given time to start the exposure and after it finishes, shut down the lamp (that would be easier, as the cord then does not have to be able to close the cover back).
And if you are not doing that too often, you do not need that "remote controlled" cover, just open it manually and without looking into the lamp direction immediately leave that room. Then shut it down just by an electrical switch.

Of course, in all cases the room (or box) has to be well ventilated, as either way of using the short wave UV, it generates O3 and NOx as well and both are rather toxic...

After I have been tinkering with 120v preheat series choke ballasts to run F10T8 fluorescent tubes at full power, I have discovered that low ballast factor 13w GX23 PL-S/PL-C preheat CFL series choke ballasts like the Sola FCF-13-TP ballast seem to run 330mm F10T8 fluorescent tubes at full power.