emulsion thickness/speedball kit

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sawzall7
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emulsion thickness/speedball kit

Post by sawzall7 »

I recently bought a speedball starter kit that i could begin printing with. I'm using the green diazo emulsion, a totally light safe drying rack and room, transparencies from kinkos, and two bba photo bulbs at recomended (by speedball instruction) levels.
I've been experimenting with different applications, exposue times, wash out, ect. My main problem has been not being able to wash enough emulsion out to make a good stencil.
Too much emulsion? not enough? need better lighting setup ?
I realize the speedball kit is extremely bottom of the barrel, is it even worth keeping? anyone have any ideas?
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d fleming
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Post by d fleming »

Try this:


step wedge test:
Print out a film or vellum, full size, (enough to cover most of the screen) use the common fonts, line sizes, halftones that you commonly print, this becomes your sample film for the step wedge.
Estimate your exposure time “take an educated guess” and then double it.
Let’s use 4 min for example when doubled it would be 8 min.
Expose the entire screen for 1/4 of that time= 2 min.
Split the screen into 7 equal sections, cover the screen with something thin and opaque like a manila folder or if you have it and are old enough to remember what it is, use Rubylith.
Cover 6 of the 7 sections leaving 1 section exposed 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 2,3,4,5,6,7, & 8 min exposure time.

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)

I hope this helps, and is not going to confuse you further.
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