[Starfirefarm]

Hi I am new to sceenprinting and am having grief with making viable stencils. I am coating my screens with chroma line chroma blue in a. Dark room and yes using the proper applicator. Getting nice even covers and then drying the screens with my drying cabinet. I have a Printa770 4 colour set up with on board drying cabinet + exposure unit. I have tried both a one to one coat + 2 to 1 coat. after my screens are burnt and I go to develop them in my washout booth I follow chromalines instructions to a T but my emulsion ends up blowing out. By time the end of the 30 second count before I even go to spray any water on it I can see the blue coming off. I am ensuring screens are 100percent dry before coating ( drying 4+ hours in drying cabinet). Then after coating have been allowing them to dry 10+ hours in cabinet. I'm being extra cautious to not preempts. I have tried exposing for all of the suggested times on my chromalines info sheet. Asked another print shop they told me to burn longer so eliminate underexposure. i have exposed up to 8 minutes still with the same results. A lady in the industry had cam out and went through the screen printing process from start through finish with me but even her screens didn't work out. ... does chromablue have sensitivities to water type? Shop is set up out of our home on the farm. Water is good drinking water(well water filtered through sand base) but is a harder water. Just running out of ideas as to what is going wrong here... suggestions everyone please

Ps brand new jug of emulsion stored in cool, dry, place - away from any lightsource

 

[TABOB]

1. First of all, exposure time depends on your light source, so there is no way to guess. you have to do an exposure test. Here is an example https://www.youtube.com/watch?v=znwuwbto4lk

2. Make your light source is actually emitting UV light. Halogen lights made with UV shielding glass, will obviously not work.
3. Make sure your film positives are as dense as possible.


I think that will do it.

 

[Manooti]

Anthem has a calculator you can use. Im using it right now for my diy exposure thinger.

I use chromablue too, when I used the the 500w halogen it was at 13 minutes. If youre using that. Remove the glass from the light and go for 13 minutes. Also, light 1.5x height to length ratio.

I dont follow chromalines instructions either. Wet both sides, wait 10 seconds, then just run water over it till it releases. Or just keep running water over it. Youll see when design starts changing color then blast it a little harder. If you let water sit too long, or spray too long the whole thing will break loose.

Emulsion is getting easier and easier the more i screw up the printing lol

 

[Bartok Spinelly]

Just a thought, and you probably are if following instructions.
Are you degreasing and drying the mesh before coating? Getting a good foamy action when degreasing is very important.

 

[jaxtell]

We have a Printa 770 also that we bought used. We had a similar "nightmare." Turns out the bulbs in the exposure unit were either old or bad or weak, not putting out enough UV to make a good screen. We replaced the bulbs with a much better result.

Also, because of the close proximity of the lights, I started using a vellum "diffusion" sheet between the lights and the film. Slowed down the exposure a bit, but still under 3 minutes. I haven't tried just printing on the vellum to make the screen yet, but will in the future.

Lastly, when washing the screen out, after soaking the screen, I let the water "work" on the image. I do this a couple of times, for about 30 seconds each, until I can see a good image starting to appear before washing it the rest of the way out.

Hope it helps!
jerry