How long do I expose my screen print screens for?   110 volt INTBUYING UV exposure unit Speedball Diazo emulsionScreens:16x2010x14?

I’ve never done this before and I’m having a hard time finding general info for a uv exposure unit. 

Update:

Screens: 10x14 and 16x20

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  • 4 weeks ago

    Depending on the screen material and lamp intensity, it could be anything from a few seconds to a few minutes.

    Do a test exposure to start with.

    Make a mask with metal foil, with just a small area cut out, a fraction of a full screen.

    Mark lines on one edge at equal intervals, eg. 10 over the width of the cutout.

    Put a piece of cardboard over the cutout hole, so just one mark width is open through to expose the screen. expose for a brief time.

    Move the cardboard another mark open, expose again, the same short time

    Repeat until the last exposure is with the whole cutout open.

    That gives you an exposure range of ten to one is a single small area. If none of the strips are correct, & its underexposed, repeat using abou five times longer each strip.

    If it's overexposed, use one fifth the time for each strip.

    (When I was using screen printing for circuit boards some decades ago, the photo sensitive material was just a gel film and you applied that to the screen with a roller - the screens themselves could be washed out in solvent and re-used).

    Something like this, possibly:

    https://www.artquid.com/art-materials/ulano-cdf-ma...

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