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Need major help from the screen printing vets!

Discussion in 'Screen Printing' started by ONLINE SIGN GUY, May 2, 2011.

  1. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    Hey everyone, we purchased a screen printing business that was going out of business, all equipment works great, 1 huge issue though....

    We can get the emulsion to hold on the screens, I have a screen printer with over 10 yrs expierence that is stumped as well, we are using SVP Hybrid Emulsion, blue in color, purchased through Ryonet, it is a one part ready to go emulsion for both graphic and textile applications, brand new, just opened.

    when we go to rinse after burning, it image just washes away and looses all detail, its like it has not bonded to the screen, the first 18 screens we did were all rand new out of the box, after those failed, we reclaimed and degrease just in case there was something on the new screens, same issue, we then to degrease older screens, same issue, we have adjusted burn time, let sit for 2 days to dry, and same issue.

    Can anyone give me any insight to what might be causing this, thank you in advanced!

    :thankyou:
     
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  2. studio 440

    studio 440 Member

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    try new emulsion make sure screens are clean
     
  3. Just Another Sign Guy

    Just Another Sign Guy Very Active Member

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    new screens. i would make sure that you abrade them so that they have tooth.

    it is rare that i have encountered a new 'bad' batch of emulsion but it does happen. in the grand scheme of things it is cheap if in question get a new batch.

    since you have not achieved exposure yet...i would error on over exposing the screen big time jsut to make sure you are capable of exposure with the set up you have since it is new. then using an exposure calculator calculate the correct exposure time for setup.
     
  4. Accelerated Graphics

    Accelerated Graphics Active Member

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    are you using a vacuum exposure unit??
    sounds like the screen is not flat against the glass...
     
  5. chopper

    chopper Very Active Member

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    burn time not long enough??
    I had a similar issue with the emulsion I am using I was told that it could be exposed to white light, the way I understand it is if the emulsion is exposed to white light it will slow down the emulsion cure time or burn time if you will, so it will take longer to burn the screen, I thought it would be the opposite that it would set faster, but the supplier says that is a misnomer, and the opposite is true, so if you exposed it to white light try a different batch, of emulsion and do it under yellow light ( bug light you can buy at wall-mart) and see if that changes things, ....P.S. I am no expert just got into this about 8 months ago,
    //chopper
     
  6. Rodan68

    Rodan68 Member

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    Some emulsion needs to be mixed with an activator before using. Not sure about the one you're using.
     
  7. tomence

    tomence Very Active Member

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    The one he is using is already premixed ready to coat. I would say not enough exposure time. And it all depends of what kind of exposure unit he is using.
     
  8. phototec

    phototec Very Active Member

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    Follow the directions.

    :thumb:
     

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  9. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    Hey everyone, i see allot of talk over the night, we did pull that pdf of the instructions, this is when we dropped the exposer time down, it is a emulsion that's 1 step, no additive, this morning i used a bit of the old 2 part emulsion, im going to see if that works, I wouldnt think i got a batch of bad emulsion but i guess im about to find out, thanks everyone, Ill keep you posted.
     
  10. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    OK, that was quick, on this all the emulsion washed away, no image at all, I may not have burnt long enough but this stuff didnt hold at all? I'm stumped?
     
  11. Goofball

    Goofball Member

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    What type of exposure unit are you using? Here is another simple test. Coat a screen and sit it outside for about 30 min. See if the emulsion cures and holds on it. If it does then that tells you that there is some kind of exposure issue going on.

    Bob
     
  12. njshorts

    njshorts Active Member

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    Suggestion:

    2 part diazo (get a cheap quart from atlas or red alert, just to test... we prefer Saati), check your exposure time (our 6-bulb is 8 min MAX), make sure the screens have been properly cleaned and DEGREASED.
     
  13. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    We have a Brown brand exposer unit, I believe 6 or 8 bulbs?
     
  14. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    Bob, so coat the screen with a image taped to it and leave outside?
     
  15. njshorts

    njshorts Active Member

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    really, really stupid question- how long are you allowing the screens to dry after applying emulsion, and do you have air movement in the space/dryer?
     
  16. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    Let me ask this, will exposer time effect the bonding of the emulsion, we loose detail and the centers of letters disappear because it turns to gel and washes away, we did the recommended time for exposer based on the manufacturers info, im sure you can over expose a emulsion...correct?
     
  17. ONLINE SIGN GUY

    ONLINE SIGN GUY Member

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    we have tried from 6 hours to overnight, in a drying cabinet, same results.
     
  18. njshorts

    njshorts Active Member

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    absolutely. there's a fine line between under and over exposed. how are you clearing the print after exposing the screen?

    Use an exposure calculator in varying times or do it the slightly less exact way- burn a few halftones on a few screens at varying exposure times- starting with an average of the exposure unit's recommended time/emulsion's recommended time and work out longer and shorter in 2 min increments.

    Your emulsion should dry in 2-6 hours (depending on brand/condition). Our diazo drys on the rack with little air movement at 75 degrees in about 2.5 hours.
     
  19. d fleming

    d fleming Very Active Member

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    Sounds like either bad emulsion, contaminated fabric or poor/incorrect light.
     
  20. Goofball

    Goofball Member

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    Coat your screen....let the emulsion dry.....tape your film to it and just sit it outside in the sunlight for an hour or so.....take your film off and rinse and see what happens.....you're not looking for quality this way you're just looking to see if your emulsion is ok....if your emulsion is washing out and turning to gel...then I would say 100% that you are not curing the emulsion enough.....check your bulbs....do you know how old they are? Make sure they are the right ones....but seriously try the sunlight test and see what happens there.

    Bob
     
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