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
