Washing out screens

[Maxie]

I used to use diazo emulsion and was told to wash out the image from the outside (platten side) and to also rinse the inside.     This we had to do because our exposure unit was not the greatest and it was always a little slimy on the inside.   If we did not rinse it we got a haze in the image.
Today I am using Photopolymer emulsion and a LED that exposes well so my question is do I still need to rinse the inside and can I wash out from the inside, I'd prefer this because then I am not looking at the image in reverse.

[Colin]

you want water to run water over both sides of your image.  Greg Kitson has a great youtube video of how his shop does it.

This helps to 1) moisten the image area for full release of fine details/halftones quicker  2) Will let you know if any underexposure has happened as you can run your finger over the squeegee side to feel if its slick.

All water pressure should be applied to the shirt side of the screen though.  The emulsion is toughest on this side resulting in far fewer image blowouts.

[Atownsend]

A post exposure dip tank saves us lots of development time (thanks TSB). We use photopolymer, but i bet its even better for the scummy diazo stuff. I still flip & rinse both sides, but 90% of the rinsing is on the shirt side to prevent any mishaps. Takes us about 20 seconds / screen once its out of the tank and in the booth.

[Maxie]

I do have a soak tank before wash out.
I tried to wash out from the inside today.    Works but I got wet, for some reason the frame profile makes the water bounce back at you (using the pressure washer)
I have two seperate rooms for opening screens and cleaning them but one pressure washer, I connected two hoses to it, one is about 10yds long.

[Frog]

I think that you are asking for trouble.
I have never seen the memo that supercedes and cancels out the standard development procedure like this from Murikami
Gently spray both sides of the screen with
cold to lukewarm water, wait a few seconds
to allow emulsion to soften then wash print
side of screen until image is fully open. Rinse
both sides thoroughly and dry. The use of a
drying cabinet or fans is recommended to dry
the screen. Use a pressure washer on fan
spray for developing the screen.


As someone else mentioned, developing from the inside raises the risk of blowing out fine detail. If not today, then sometime down the line.

[tonypep]

Just to throw this in..........Machines like the Eco Rinse use power jets on both sides and develop perfectly every time

[RICK STEFANICK]

Just to throw this in..........Machines like the Eco Rinse use power jets on both sides and develop perfectly every time

Your spoiled my friend.

[tonypep]

Just as thankful as spoiled though

[ABuffington]

Images wash out differently on diazo and dual cures vs. pure photopolymers.  Diazo and dual cures melt easily while it takes a bit longer to soften a pure photopolymer image, hence dip tanks help out a lot.  A fully exposed screen on a pure photopolymer will often need a pressure washer development set to fan spray and may need to have fine halftones hit quickly at close range (3-6") to open them up. 

If you have slime on the inside of the screen it is underexposed and needs more time.  The emulsion's ability to withstand full exposure for press durability and to obtain desired resolution often depends on the d-max of your film and your emulsion of choice.  When rinsing the inside of the screen it only needs a light rinsing.  If you are using a pressure washer, spray the inside of the screen at an angle of 20-30 degrees to the plane of the screen.  Never spray at 90 degrees straight on or your 80-90% negative dot can be washed off with hydraulic pressure.  If your image gets plugged with emulsion when dried, up your exposure time. 

If you have image areas that won't wash out then check the dmax of your films. If you can see through your film in most cases the exposure light can get through as well and lightly expose the image making it difficult to wash out.  The other time the image won't wash out is if the diazo or dual cure is past shelf life and the diazo has dark hardened.  This can also happen if you store diazo or dual cure screens above 80 degrees for long periods, or the emulsion or diazo has been left in hot rooms above 80 for a week or more.  One advantage of pure photopolymer emulsion and coated screens is they can be stored at 100 degrees for long periods with no ill effects.  The emulsion also has far longer shelf life of a year or more, vs 4-6 weeks for diazo and dual cure emulsions once mixed.