 Re: Photographic screen error
Be descriptive.
How you made your positive; if you didn't meet minimum known standards, it could leak UV energy that will cross link the sensitizer and make it hard to dissolve with water and wash down the drain.
What emulsion? The ghost you refer to could be parts of your positive that were taped together - or caused by poor vacuum.
What vacuum?
You shouldn't have to blast. Water will dissolve the un-exposed parts of your stencil.
"The part where it's supposed to be uncovered by the emulsion, didn't chip-off." I don't understand this sentence. Emulsion is easy; If it doesn't wash out, it was cross linked somehow. If the emulsion washes out - it wasn't exposed with enough UV-A energy, so it dissolves with water and goes down the drain.
You had to scratch the open area. I assume your positive failed.
Dime Complete Opacity Test
For your next exposure, tape a dime to the stencil to see if the dark areas of your positive are failing you and letting UV-A energy through to the stencil. If the area covered by the dime doesn't wash out, you have exposed the stencil to UV energy or heat energy and the stencil is resisting dissolving with water and going down the drain.
More emulsion just means longer exposure.
Quartz halogen lamps are designed for living rooms even though they get so hot. The safety glass is there to protect your eyes from UV energy.
Search for 'exposure test' on these forums.
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How are you measuring? retired Ulano Technical Support
Screen printing since 1979 - SGIA Academy Member | 
