Lawson Expo Light

[travis.hoyme]

I have a Lawson expo light.  It came with daylight bulbs, and I've switched them out with black lights.  When exposing my screens I'm losing edge definition.  Am I doing something wrong?  I'd like to start doing more halftone designs... process, simulated process printing.  Can I do it with this light or do I need to upgrade?


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[Screened Gear]

I don't know that unit but I will give you some advice on this.

1) any exposure unit can do halftones. Any one that disagrees is trying to sell something or is lacking skill or knowledge. I have exposed 55 LPI halftones from Ghost Rip on a home made 500w shop light setup.

2) You need dark film. the darker the film the longer you can expose the better the screen is.  Dark film makes it harder for the light to expose your design. If your exposing your screen and the design is coming off in sheets or strings then your film is not dark enough or you exposed too long.

3) Expose for the right amount of time. If you expose for the right amount of time your design will wash out easily. You will not lose any detail.

[jvanick]

does that unit have a vacuum blanket?

And I agree with what Jon is saying... within reason, you can certainly expose decent halftone screens with just about any light source.  Better lights make life easier, but you can even expose halftones with the sun, assuming a tight enough mating of the film and the screen.

What kind of printer are you using to make your films?

[Screened Gear]

I was just saying it can be done. Exposing halftones on a shop light takes about 13.5 mins. I would never wait wait that long now but it can be done with very good results.

[Frog]

That unit has the most important feature for holding detail: a vacuum blanket that gives the most important thing: good contact between the emulsion and glass.

The unit originally had black light tubes, and hopefully, you got the real deal with your replacements.

So, with good films, proper exposure times (did you do a step wedge test to establish this?) flat screens, and everything working as it should (are you getting good vacuum?) you should get professional results.
 

So, you have a bit of a checklist now. Report back please 

[3Deep]

Travis I see your new here  how long you been printing? hang around to long and you might learn something....bunch of great printers here, artist etc  welcome the guys have already answered your question for ya good luck.

Darryl

[travis.hoyme]

It does have a vacuum blanket


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[travis.hoyme]

That one was on an laser jet 5000 with Casey's translucency.


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[travis.hoyme]

Been printing about 12 yrs now, but my brother and another employee does most of the printing.  I do some embroidery, and run the office, customer service etc...


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[travis.hoyme]

I just got a epson 1430 with t-rip.  I think that will help printing darker and on clear film.


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[Frog]

I just got a epson 1430 with t-rip.  I think that will help printing darker and on clear film.


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and also give you better shaped dots.

[rockerdude]

I have the same unit have the daylight bulbs in it.
I can print any halftone thrown my way. I'm at 4 minutes 10 seconds on a 305 one and one with ulano orange and can print a greyscale photo better than most inkjets!  Lol I'm using accurip with an Epson 1100 & 1800.

[travis.hoyme]

Thanks!


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[travis.hoyme]

Have you ever used black lights in it.  I recently had someone tell me that it would be better to use black lights.


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[Frog]

The description for the current Expo-Light merely refers to the tubes as "dynamically balanced". Are these the "daylight" tubes?

I assume that they came up with tubes which emit a wide spectrum to work with a variety of emulsions(as emulsions can very slightly in their optimal UV needs. Many Fluorescent units do indeed come with actual unfiltered black lights, very rich in UV around 365 nm. These are the ones that are referenced when an emulsion manufacturer like Ulano gives exposure guidelines for various common light sources to get starting points for step wedge calculations.