# Exposure with 60W Blacklight and 150W Fluorescent



## tang3 (Feb 28, 2010)

Hello,

I am just beginning to screen print, and I need some help with exposure; specifically what kind of bulbs to use.

My first attempt:
100 Watt Bulb with metal "roof". (picture attached)
111 mins, 15 inches away.
The image didn't show up enough; it could only be seen when screen was held up to light and at an angle.
I am hoping this was due to the emulsion I used that had been sensitized 9 months earlier.

I just coated my second screen, and have not yet exposed it, and have decided to use a different bulb for exposure, because I don't think that it was just the old emulsion that made the image barely show up. I think it also had to do with the fact that the bulb was not "powerful" enough.

So I went to my local hardware store and bought a 150 watt Energy-Saver Fluorescent Light Bulb. (Picture attached)
It says it actually only uses 42 watts, but it replaces at 150 watt...does this matter?
Would this work if I used the same settings as my first attempt?

I also went ahead and bought a 60 watt blacklight. (picture attached)
This one is also an energy saver, and it says it actually only uses 13 watts...once again..., does this matter?
What would my settings be when using a black light?
I read 3 minutes, (I don't remember where), but I think whoever wrote that was referring to using an exposure unit.

For someone like me, what would be the best way to expose?

If anyone could give me info about any of this, it would be very helpful and greatly appreciated.

-Tristan


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## jsf (Aug 4, 2009)

tang3 said:


> Hello,
> 
> I am just beginning to screen print, and I need some help with exposure; specifically what kind of bulbs to use.
> 
> ...


I am not if those bulbs will give efficient UV distribution needed to your exposing process or the light beam may not be enough to cover your screen. Although those may work but you need to find the "right" distance of exposure and time and depending on your emulsion type you are using.

During my old days as I always tell my colleagues, I use the sun for my exposure during daytime. And I do some exposing with 2 pcs of incandescent bulbs of 60W each for 25 mins during night time. Successfully.

Now I use 4 pcs of flourescent blue bulbs installed in a box and a clear glass on top about 6"-7" distance at about 1 min. 

Anyway here's a thread you can look into (http://www.t-shirtforums.com/asia/t115249.html) and see some pics of with an ideal and effective exposure unit should be. 

You are welcome to ask and post your questions in the thread...

Goodluck.


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## BroJames (Jul 8, 2008)

If you do not want to shell out much money at this time, a 500w halogen bulb may be more suitable. It should expose in 6-10 minutes 18 inches off the artwork. Remove the glass at your own risk.

A 250w mercury lamp is also an alternative. It cost just lighlty more than a 500w halogen but expose in 1-2 minutes after 3 warm up. Some suggest it is better to warm up for 10 minutes.

These 2 are the cheaper alternatives I've tried that works. I've tried 50w CFL which has a higher wattage than yours but unable to expose in about half an hour. I found that too long so I moved on - to halogen, then mercury.

If the black bulb in the picture is an UV bulb, it will have more UV which is needed for exposure. However, since it is a bulb, you have to raise it to about 16 inches for a letter size (or A4 size) image. However, I don't think the low wattage will have that much power to throw the UV that far.


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## tang3 (Feb 28, 2010)

A 500w halogen as in a work light, or a tube light? Could you please post a link to a good 500w halogen?


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## superD70 (Dec 22, 2010)

http://www.walmart.com/ip/Bayco-500-Watt-Halogen-Project-Work-Light/14003469

Sorry if wal mart offends you, it was the first link I came across


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## BroJames (Jul 8, 2008)

And this is how one of the possible the setup looks like
[media]http://www.silkscreeningsupplies.com/files/799934/uploaded/cure-lamp-stand.jpg[/media]Firstly, a halogen lamp is a poor source of UV and does not have the best UV spectrum for exposure. However, many people including me, used it before jumping to something more suitable later. The reason is the cheap cost and easy DIY. Actually, I happen to have 2 available and the only DIY I did is hang it below an ironing board. 

Another simple DIY is to affix the lamp on a piece of wood about 2 feet long and lay the wood atop 2 chairs. 

Others just buy a stand for the lamp, or use a guitar stand
[media]http://www.wholesaleec.com/upload/upimg15/11425825105.jpg[/media]Others use 2 lamps
[media]http://www.chinawholesaletown.com/wholesale-Halogen-Work-Light-with-Tripod_101461/uploadfiles/20101213/81384fcbd37c8d541f5f4410948925c7.jpg[/media]Still others just affix the lamp on a wall and make a shelve underneath. 
[media]http://www.youtube.com/watch?v=1OIpRQt9ttY&feature=related[/media]However, in comparison with a roof light, it would be more suitable.


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## tang3 (Feb 28, 2010)

Thank you. I just bought a 500w halogen and I was planning to do like you said with the chairs.


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## foot print (Jun 2, 2010)

you can build a stand for your halogen lamp out of PVC ...you really don't need a diagram just pay close attention to some of the pics posted and go from there...it's all about DIY in the end it saves you some cheese ( $$$ )


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## Alan Buffington (Oct 27, 2010)

Screen exposure needs strong light. the industry standard is a 5,000 watt multi spectral lamp.

While the lamps shown on this page will eventually expose a little bit of the emulsion and create an image, they require long exposures to get even a minimal image. Halftones and fine lines suffer. Forget about discharge and waterbase production.

The sun is your strongest do it yourself light source.

Here is a link to building a sun exposure box. I ran a 3 auto company before getting my first 7,000 watt exposure unit. Just shoot with the sun between 10 and 2, or 11 and 3. Better in the summer. Northern latitude folks will have difficulty in the winter using the sun.

[media]http://66.221.175.239/documents/SunExposureUnit.pdf[/media]


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## BroJames (Jul 8, 2008)

I also tried the sun for exposure earlier on. No doubt it's the best source of UV for exposure but so many variables to contend with. Problem compounded by climate change where the la nina phenomenon now brings rains in December. 22C now at my shop which is pretty cold for a tropical country. We have mall airconditioning though but that's still low. News reports place the temp in the aircondition-less uplands at 6C. My wife have relatives there and whole crops are at risk of being lost due to frost. I am assuming that sun UV is also affected making a good exposure less predicatble.

Still, nice to try it out.


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## VinylHanger (Jul 16, 2010)

If he is just figuring out how to expose a screen, I doubt he is worried about halftones at this point. I use a 500 watt halogen clamped to a piece of L-channel which is clamped to a shelf 20 inches or so above my workbench. I have no problems with fine lines.


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## BroJames (Jul 8, 2008)

I have no exposure problems with halogens too. Well, except the high wattage and longer exposure time but these are delicacies that someone who simply wants to eat (or expose screens) can do without. On the plus side, they're cheap and easy to DIY. 

Being able to print first is more important than worrying about the best equipment or best exposure that may really take a while, years maybe, before most people can appreciate or needs them. As they progress, make more money or gain more experience, they can decide if they want to change exposure units later.


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## Alan Buffington (Oct 27, 2010)

As I pointed out you can make screens with low wattage systems and they are fine for short run hand printing. The question is how much of the emulsion is completely cross linked? With stronger light systems you get stronger screens, with weaker light systems you get weaker screens, again fine for hand printing, a disaster for long run automatic printing, especially if you use discharge or burn out inks.

For sun exposure it helps to have clear skies, cloudy days won't work well. The sun unit simply provides a back up, and yes you can shoot halftones with good dark film with very short exposure times that won't undercut like long exposures. Sun simply provides a stronger screen to withstand water base inks than can be obtained with DIY units. You can use the sun on SBQ emulsions to post expose a screen developed on a DIY system to completely cross link the emulsion. 

This also helps in reclaiming since the unexposed SBQ pure photopolymer emulsion remains sensitve and can be chemically flashed by screen openers, mineral spirits, acetone, MEK, during clean up making reclaiming difficult. Post exposing even on a cloudy day, or post exposing in your DIY exposure unit at 2X the exposure time helps the emuslion to reclaim easier.


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## BroJames (Jul 8, 2008)

Are SBQs easier to post expose than dual cure?


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## Alan Buffington (Oct 27, 2010)

Yes, SBQ remains sensitive after development. It is a good idea to develop in a light safe area. Dual cures will also post expose but since they are half diazo only the SBQ part remains sensitive to light.
If printing Waterbase discharge it is also crucial to dry the screen well before exposure and before printing. Drying refers to the inside of the emulsion being dry, not necessarily dry to the touch.


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