washing out

[gozo]

I exposed my screen for 70 seconds in the sun, then did my washout without a pressure washer.

My question is, should I leave the light on or off while rinsing th screen, as it seemed to take quite a while compared to the last time without the light on?

[James flames]

I keep a spray bottle filled with distilled water, set to 'mist', and I spray my screens on both sides right after exposing, just to get it a little moist. You should see a little ghost of your stencil at this point. I leave it like that for a few seconds, then take it to the power washer and wash out the screen, with the lights on of course (you need to see if you got all the bits out of the stencil).

That little bit of moisture should slow down the un-exposed emulsion, and also loosen it a little so you can wash it out more easily. Just so long as you don't wash it out in front of the sun or any other heavy UV lights, you should be just fine. If you are having trouble washing out, you probably need to adjust your exposure time - 70 seconds sounds REALLY long. Should be about half that.

[The Fresh Prints]

sounds like over exposure. james is right on the money with his explanation.

[greasy_granny]

Man I always just use the regular hose to wash out screens. Are you guys standing way back with the pressure washer?

[Andymac]

we only use the power washer for reclaiming or really stubborn emulsion that either over exposed (start leaking through your weak-assed positive) or is getting old - old emulsion starts to get hard to washout.

70 secs with a diazo based emulsion in direct sun is over exposed I think.

After a good washout, was the squeegee side of the screen sticky or slimey? if it isn't you can back your time down a notch. If your detail didn't expose well, then definately back it off. If it is slimey (after a good wash), you need more time.

[gozo]

The only part that was a bit slimey was the part that was covered with the stencil.the rest of area that was exposed was OK.
I gave it 70 seconds because it started being a bit cloudy, tomorrow I'll try a new one and will reduce the time to 45 seconds.

[gozo]

I followed the advice of you guys and tried a new exposure on 45 seconds and bang on, it came just right.

[James flames]

45 seconds and bang on, it came just right.

I'll assume we're still talking about screenprinting? Right.