I began to burn 110 screens using CCI ProChem DC-Plus emulsion. I'm using a SAATI 21 step guide to find the correct exposure for my screens. I have a new Ranar CBX 2024 exposure unit.
My question, why did my stencil completely blow out on the image (and registration marks) when exposing for 12 minutes? (I have no picture of this screen as I reclaimed it right away.)
My first test was done at 8 minutes (see image below):
then I did a 10 minute test:
On both these screens the image (art) came out fine, with the first (8 min.) being a bit sharper. Registration marks were also good and sharp on the 8 minute exposure.
According to SAATI, and on my first exposure, I had to increase my exposure time by 1.4x, increase one step. 8 x 1.4=12.2, this gave me ~11 mins. and 20 secs.
But, when I burned the screen at 12 minutes, the art (and reg marks) washed out completely.
Process in washing out: rinsed the print side first, then the squeegee (ink) side. I let sit for about 45 secs. then used pressure washer (not hard sharp pressure, but flat pressure) at about 3 feet distance. **This was done to the 12 min screen. For the 8 and 10 min screens, I used a nozzle (the one most use.)
I did use bottled water to mix diazzo(sp) and let mixed emulsion sit for 1 30mins. Did a two-one emulsion coating. All processes were done under yellow lights. Ambient temp was in the mid to low 60s.
One thing, I did not use a fan to dry out my screens upon coating. I did leave them to dry for 24 hrs in my Ranar job rack, ink side up, fully covered from light. But, it did rain overnight and my rack is inside a large tent that's enclosed.
Could my inconsistency with washout be due to emulsion not fully dried? I did not feel any wet spots upon inspection, before exposing.
Thank you, in advance, for any insight.