Baby Joe 2000

[travis.hoyme]

Is this new uv light technology the way to go compared to a metal halide light source?  It looks like over time it'll save money in bulb replacement etc... I have a Lawson expo light and was thinking about upgrading.


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[Frog]

You need to hang out and read a bunch of old posts here. I don't have the links handy, but our own Blue Moon tested and wrote about the baby Joe, (way way back when it actually was the Baby Joe)
It is now marketed by Vastex.

M&R also has LED units, and more than one member here has bought them and reported back.


Yes, they are the wave of the future.


Now, not to discourage you from upgrading in the least bit, because exposure units are darn important, but you will get significantly better results with the Expo Light you already have (and have posted about), with your new ink jet films, and once you dial in your exposure times.

[Gilligan]

Funny how quick that technology went from naysayers to full on believers.

[Sbrem]

I seem to recall that Pierre was impressed with it...

Steve

[travis.hoyme]

It seems like since I changed out the daylight bulbs for black lights I've had trouble.


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[Frog]

What blacklight bulbs did you use?
There are "party" type, and unfiltered. For emulsion exposure, (and turtles,and other amphibians) you want the unfiltered bulbs like these:
http://www.topbulb.com/20w-t12-fluorescent-blacklight-medium-bipin-base

Next, how did you determine your exposure times for the original bulbs, and now, the black lights?
Is this a job for Step Wedge Man?

[travis.hoyme]

http://www.atlantalightbulbs.com/ecart/10Expand.asp?ProductCode=F40T12BL#page=description

This is the ones I purchased.


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[Frog]

Okay, those should do the trick with most emulsions, so now, on to answering question #2...

[blue moon]

those are 350 nm bulbs. the old ones could have easily been 395 nm and worked better with the emulsion you use. . .

pierre

[travis.hoyme]

The old ones weren't black lights they were day lights.  It seems like the black light bulbs are working better with under exposing the screens due to the emulsion not feeling slimy now.  Should I just use the day lights?  What really are the differences between the 2?

[Frog]

The old ones weren't black lights they were day lights.  It seems like the black light bulbs are working better with under exposing the screens due to the emulsion not feeling slimy now.  Should I just use the day lights?  What really are the differences between the 2?

This should be a revelation! Not slimy means not underexposed!

I ask again, how are you determining your correct exposure times with each of these light sources?
This is definitely starting to look like a job for Step Wedge Man (and folks out there who have met him are cringing!

A proper exposure time will depend on an emulsion getting the correct amount of correct UV to allow it to completely cross link.
That will change with light sources.

I am suggesting an exposure calculator or manual step wedge test for determining the amount of time or light units required to completely cross link your emulsion without closing up small detailed open areas.

[Frog]

Some instructions for a manual test from old forum friend Ken Brown, since retired

Sorry this is so long winded - Here are some basic step wedge instructions.

STEP WEDGE INSTRUCTIONS
Start with a properly coated, and dried screen.
If you would like basic coating instructions let me know.

Print out a full size film or vellum (enough to cover most of the screen). Use the common fonts, line sizes,halftones that you often print. This becomes your sample film for the step wedge.
Tape the film to the "print side" of the screen (not the glass)
Use an estimated exposure time based on the emulsioin manufactures recommendations a guide and then multiply them by 2.
For example, 110 White Mesh with estimated exposure time of 3 minutes would double to 6 minutes.
Expose the entire screen for 1/6th of that time (1 minute).
Split the screen into 6 equal sections, cover the screen with something thin and opaque like a manila folder, or if you have it, use Rubylith.
Cover 5 of the 6 sections of the screen leaving 1 section exposed to the light and expose for 1 min.
Slide it over to expose 2 sections of the screen and expose for 1 min, etc .
When you are finished this will give you a 1, 2, 3, 4, & 5 minute exposure test on 1 screen.- you can also vary the times from 1 min to 30 or 15 seconds when you get it dialed in closer.
When washing out the screen, pay careful attention to how it is washing out:
If it is under exposed the inside (squeegee side) of the screen will be slimy
If over exposed the fine detail and or halftones will fill in and you may start to see some saw tooth or jagged
edges. If you have weak density on your film or vellum the light may burn through some areas so underexposing the screen may be your only choice.
Somewhere within this exposure test you should be able to find a good exposure time for that mesh count.
You can use that exposure time for that mesh count to estimate times on your other mesh counts.
Keep in mind that the courser mesh counts will have longer exposure times because the mesh is thicker and it holds more emulsion (more emulsion = longer exposure).

Please feel free to call me with any questions that you may have. I can also walk you through the entire screen coating, drying, exposing, and developing process.

Ken Brown

[sqslabs]

Best picture ever.  And thanks for sharing the great tutorial.

Keep in mind that the courser mesh counts will have longer exposure times because the mesh is thicker and it holds more emulsion (more emulsion = longer exposure).

Have you ever had an "a-ha" moment that made you feel like a complete idiot at the same time?  I just did.

[Frog]

Best picture ever.  And thanks for sharing the great tutorial.

Keep in mind that the courser mesh counts will have longer exposure times because the mesh is thicker and it holds more emulsion (more emulsion = longer exposure).

Have you ever had an "a-ha" moment that made you feel like a complete idiot at the same time?  I just did.

One of the advantages of Capilary film is consistent thickness, on any mesh.

With liquid emulsions, this why, a conscientious person will do this test for each color of each mesh count with each emulsion used. Tedious!

Now, the commercially made exposure test films like the highly rated Stouffer or even the freebie Ulano can do a test in one step.
However, there is an added benefit to the manual method because it uses the exact film (or other media) with the actual d-min(clarity of film) and d-max(opacity of image) that will be used for production.

Besides, it also allows for the occasional appearance of my friend, Step Wedge Man.

[Doug B]

  I haven't seen Step Wedge Man since the old boards...
Now I need a drink.