UV exposure usnit question

[mark]

Is there any reason a person cannot use a stripped down shop light to use in an exposure unit?

There is a lot of talk about getting the right ballast for BLB bulbs but in a Shop light that costs about US6 dollars. You have a complete fixture for two bulbs. Why can't a person just strip one of these and use the parts? I am not looking to cut corners but it seems that people spend a lot of money needlessly.

 

[Michael Mutmansky]

Mark,

Sure, people do that all the time. Just make sure that the ballast and the UV lamps you are getting are designed to match. Most of the UV lamps are T-12 lamps, so make sure that the shop lights are designed for T-12 lamps, and everything will work.

Cheap magnetic ballasts do use more energy, though. That's why I don't recommend them. Doesn't mean you can't use them, but I try to be as energy efficient as I can within reason.


---Michael

 

[sanking]

Mark,

Cheap magnetic ballasts do use more energy, though. That's why I don't recommend them. Doesn't mean you can't use them, but I try to be as energy efficient as I can within reason.


---Michael

The magnetic ballasts also won't allow the tubes to put out as much radiation as you can get with electronic ballast. The figures I have seen suggest that you will get from 10% to 20% more radiation with electronic ballast. However, note that many of the shop-type two-tubes units can also be purchased with electronic ballast, though you will have to pay slightly more for it .

Another thing, you mention BLB tubes. All other things being equal you will get slightly more radiation with BL tubes, and the BL will probably cost less as well. I actually use 48" BLB tubes in my UV bank but that is because they were available locally and I had some concerns about shipping.

I estimate that the use of electronic ballast and BL tubes instead of BLB would amount to about a 25% - 35% increase in speed of printing, i.e. your exposures would be 25%-35% shorter.

Sandy

 

[mark]

Thanks guys. I have been reading all of the stuff I can find on building one of these and it sounded like folks were spending way more money than necessary. Still sounds like they were. I have a surplus of shot light (the wonders of being able to upgrade a hydroponics garden from a butt load of 48 inch flourescent plant lights, to HID. Good to see they wil get use

 

[Michael Mutmansky]

Mark,

Make sure that you use ballasts that are identical for the unit.

What Sandy says has about output with magnetic ballasts has to do with something called the ballast factor, and it is one way that many magnetic ballasts reduce power consumption. The problem is, every manufacturer uses different ballasts factor set points, and even within a manufacturer's lines, it will vary.

The ballast factor can be as much as aboit 20% different for normal ballasts, so the best way to ensure that you don't get any stripeing in the prints, it is best to ensure you are using exactly the same ballast for all the lamps.

It's also a good idea to alternate the lamps in the fixture so that a slightly out of spec ballast won't create a two lamp wide dark spot. if you alternate ballasts in the lamp placement, a dark spot will only be one lamp wide, and may never cause any problems.


---Michael

 

[eric]

If you were to *JUST* make small prints (I'm getting a 6x9 soon) for practice. And not spend a million bucks. What do I need that I can get from my local home mega store? Grow light? Those cheapo cone light fixtures?

 

[sanking]

If you were to *JUST* make small prints (I'm getting a 6x9 soon) for practice. And not spend a million bucks. What do I need that I can get from my local home mega store? Grow light? Those cheapo cone light fixtures?

If you only want to do very small prints, certainly no larger than 8X10, you could buy one of the 175 watt mercury vapor yard lamps, available at most home supply stores for about $40. They put out a lot of UV radiation but you will need to position it fairly close to the printing frame to get short enough exposures with UV processes, but this is certainly feasible for small prints.

BTW, if anyone really wants one of these I have one in the attic that I will sell for $20 plus shipping. The unit has virtually no time on the bulb because as soon as I purchased it (years ago before I knew much about UV sources) I realized that it would not work for large prints, say 11X14" and over becaue of the long exposure times.

Sandy