# Halogen Lamp bulbs/ exposure time adjustments advice needed



## rema (Aug 7, 2006)

Hey every one, I finally got stuff sorted got images printed I directly onto acetate and other bits and pieces.

But when I went to test my lamps one wasn’t working thank God I hadn’t coated the screens first. so I thought it would be straight forward to get a replacement bulb boy was I wrong I tried local hardware stores and the internet but cant find any 250w ones thats will fit in my lamps, I can only find 300w, 500w and 200w ones

My current set up was 2x 250w lamps so thanks 500w for 9.30mins so I was thinking that as I can't seem to find any 250w replacements that I could buy 2x 300w ones as my local hardware store sells them and adjust the exposure time but I don’t know how to do this or should I get 2x 500w and half the expose time is it that’s simple

Any advice and suggestions are welcome need to get this issues resolved as soon as possible as it’s stopping me doing anything.

Blessings rema


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## rema (Aug 7, 2006)

can any one help...


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## natedidit (Oct 23, 2006)

I would say either or will work, but with either decision you are going to need to experiment a little to get it right after switching bulb wattage. There are other variables to take into account, like distance of light from the screen and whatnot, so I don't think anybody will be able to give you a dead on figure that's going to work perfect for your setup. 

Trial and error. Don't worry, you'll figure it out! Do small tests or a few inches square to avoid wasting too much emulsion.

Nate


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## rema (Aug 7, 2006)

well thanks for the advice i think i will shorten the exposue time and that should do the trick seeinng as it not that far a jump in wattage 500w to 600w


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## Fluid (Jun 20, 2005)

As long as the equipment will handle a higher wattage bulb, yes I would go higher in watts. Ultimately you want as many watts as you gan get.


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## Calibrated (Oct 26, 2006)

The real problem here is that a Halogen Lamp bulb is not even close to an ideal light source. Halogen is mostly white light, not very suitable to expose screens that need Ultra-Violet light to rapidly expose.

Many people start with halogen, but understand that more wattage in the wrong light spectrum is almost useless.

If your going to spend more money/time on your exposure system try looking for Metal Halide light sources as they provide a high level of UV light and thats what you need.

A good place to start looking for a bulb is here. TopBulb <-link


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## rema (Aug 7, 2006)

Thanks for all the advice but my old system even though I only used it once worked fine for me but because one of the bulbs broke and I can not fine 250w bulbs to replace it I will have to use 2 new 300w bulbs.

So I’m thinking if I expose the screens at the same 9.5mins as before it will over coat because of the extra light (is this the case?)

So I was thinking that I would have to make it a shorter exposure time to compensate for the extra watts (will I have to?)

I came up with this equation and it seems to work in theory

9.5 mins is 570 secs

So 500w / 570sec = 0.877193

So 0.877193 * 600 = 526.3158

Divided into minutes = 8mins 46secs

Does that make any sense?

Blessings, rema


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## rema (Aug 7, 2006)

So sorry everyone seems like i have been mistaken all this time my bulbs are actually 500w each and not 250w so i can just go get another set from my local hardware store sorry for wasting you guys time.


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## undrplnd (Sep 1, 2006)

all i can say is everyone have different film exposure time. like me using 500w spot light using FOTOCOAT 1838 it took 3min30sec or maybe less.


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## rema (Aug 7, 2006)

true,

well i got a replacement bulb and exposed my screen as before and it was cool 500w for 9.5mins


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