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Old May 26th, 2019 -   #2 (permalink)
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Default Re: Exposure Problems complete bust

Yes, Diazo emulsion starts to age once mixed. Lifespan depends upon temperature, but two months is too long for Diazo regardless.

Make your life easier and get a photopolymer emulsion, like Saati PHU. They expose faster, there is nothing to mix, and they are supposed to last at least a year from the date of manufacture. I used my last bucket for over two years before I used it all up. Keep it in a cool place (not freezing).

Bad emulsion is no doubt your main problem, but I'll rattle off a few more that might be making life harder than needed.

- You've taken the glass out of the worklight, right? That glass is there to protect your eyes from UV, so you want it gone for our purposes.

- Depending where you live and time of year, it can be difficult to get screens dry enough. Humidity should be under 50%. You can check this with a cheap $10 humidistat from Home Depot. You may need to use heat and/or a dehumidifier (I do in Oregon).

- Thick emulsion does not like to dry (or expose) all the way through. Thicker is not better. Especially when you have slow emulsion (Diazo), weak light (worklight), and are subject to mother nature's humidity whims.
How To - Calculating Exposure Time