hi all, im new to silk screening. i faced a 'problem' (might not be a problem to u guys) regarding to my screen after exposing it for 5.5mins under 1000 watt halogen light.
Straight after exposure, i washed the screen with a hose gun, the image appears clear enough to be seen, but is it a problem that not ALL the 'burnt' emulsion can be washed away? there still seems to be those tiny little emulsions on the on the exposure area...
Is my exposure timing either too long or too short??
when i inked on my t-shirt, there's tiny little dots which i couldnt inked on it. then, i tried to put more paint on the screen, that seems to make the artwork looks fine.
is it bcoz i put too little paint in the first place or is still the screen's problem?
The positive has an 'ink side' and a 'not-ink side', you should have the ink next to the emulsion. Otherwise light can undercut the stencil.
Is your positive dense enough? Are solids burning through?
Dave
Visit a professional to see if they will show you how it is done. That is how I learned because I banked on being able to produce the first screens myself and it backfired. Good luck!
Stick a coin on the screen as a mask, if that washes out OK then it suggests the film is no good, if that's still a problem, it's your screen/emulsion.
I am a newbie also.. I have been struggling with this. Here are some suggestions, based on my failed attempts:
(1) Make sure that your light source is not too close to the screen. Heat will "expose" the emulsion.
(2) It sounds like your positive is not dense enough. I am having this problem also. I am printing my positives on laser transparencies. I have found that stacking two positives atop one another helps. Ultimately, I need to find a better way to make positives! I assume the pros use a fancy film printer like you would use for offset printing or whatever...
(3) Play with the exposure time. Try knocking 1/3 off the time, and again, until you get a good exposure.
What kind of Halogen light is this? It's a misconception that photo-sensitive ink is sensitive to visible light, which Halogen gives off a tun; emulsion is actually sensitive to UV, ultraviolet, or non-visible light. Most halogen lights have a glass shield that blocks UV so that only visible light passes through. Your problem definitely sounds like an exposure issue and right off the bat it sounds like an over-exposure if your emulsion won't wash out. 5 minutes sounds like a very long time too; it's all dependent on your light source, distance from your light to your film, and most importantly your emulsion. Finding the right exposure time is one of the hardest things to do in screen printing and it's going to require a LOT of trial and error, and a timer. You will eventually find a perfect time that works. For me, it's 1:18 with a 1500W metal-halide bulb at 24 inches using Ulano QTX.
One other thing: if you are using standard office-supply mylar sheets as your film, they are shiny and reflect and refract light and less is going straight through to your emulsion. Toner or ink is also less opaque on these and you may be bleeding light through your mask areas. It's a good investment to buy proper matte films.
my screen cant be washed out completely? 
