Emulsion peeling on complex images, but over exposed.
Hi, i've been screen printing for over a year now and havent had many issues, i primarily use Kiwo chemicals and Permaset Aqua water based inks for my garment printing.
I recently decided to up my mesh count and take on some more complex designs to print, my inks work perfect with the new (yellow) mesh (around 56 - 71, depending) but when exposing i am having issues with getting fine detail out of my screens.
I use Kiwo Azocol Z-1 emulsion, it is a diazo based emulsion which i mix myself.
For exposing i have SIX 400 watt (2400 watts) halogen lights pointing directly at my screen which i sandwich between glass and a raised block of wood. After the maths this left me with a 10minute exposure time, but the emulsion i use is not incredibly light sensitive, so a minute either side doesn't effect the image massively.
The problem i am currently facing with fine detailed designs is that when i expose for 10 minutes the detail won't wash out, and to complicate matters: as i apply water to the screen to wash these details out, it peels the emulsion away at the edges where the image has successfully washed out, leaving me with a jagged reproduction of what i was hoping to achieve.
To me this seems like problems of BOTH under-exposing and over-exposing, but with such an insensitive emulsion, i can't see why this is happening.
I am currently trying to expose with 2 acetates taped together to give me more of an opaque stencil, but i don't see how that would help. Maybe another emulsion? I have previously achieved very high detail, but recently, it just won't cut it at all.
I use Pregan NT9 to degrease my screens thoroughly before i coat.