Need major help from the screen printing vets!

[ONLINE SIGN GUY]

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:

[studio 440]

try new emulsion make sure screens are clean

[Just Another Sign Guy]

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.

[Accelerated Graphics]

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

[chopper]

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

[Rodan68]

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

[tomence]

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.

[phototec]

Follow the directions.

:thumb:

[ONLINE SIGN GUY]

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.

[ONLINE SIGN GUY]

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?

[Goofball]

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

[njshorts]

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.

[ONLINE SIGN GUY]

We have a Brown brand exposer unit, I believe 6 or 8 bulbs?

[ONLINE SIGN GUY]

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

[njshorts]

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?

[ONLINE SIGN GUY]

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?

[ONLINE SIGN GUY]

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

[njshorts]

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?

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.

[d fleming]

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

[Goofball]

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

[John Butto]

If you have abraded (microgrit brand name from Ulano) your screens and
degreased them and your emulsion is not sticking because you feel you have followed the directions, it is your exposure time. You need to get a step wedge exposure film strip to help you get the right time for your light source. I don't know if you are using single source light or tubes for your UV but that could be a problem where you just are not exposing long enough or too much. You might also need to replace your light source since they do lose their UV after so many hours of use.

[diamondavenue]

If nothing is staying on it sounds like an exposure issue, almost as if the emulsion is receiving no uv light transmission at all. Is there new glass on the unit, or are there new bulbs? If either was replaced the bulbs could be the wrong type and not putting out the correct light spectrum, or the glass could be inhibiting the transmission of light. Put a coated screen in for 15 mins with a coin on the screen and then to try blow it out. Light obviously wont go through the coin so it should wash out even with the ridiculous time. That will give some clue as to what the issue is.

[Pro Image]

If you want to switch emulsion.....May I suggest Ulano QTX......Ive never had a problem with it and 2 minutes in the 6 bulb exposure unit and Ive got nice screens......

[SlamMan]

If you expose one in the sun you'll be able to confirm whether or not it's the emulsion or your just not getting enough exposure.

[d fleming]

If you want to switch emulsion.....May I suggest Ulano QTX......Ive never had a problem with it and 2 minutes in the 6 bulb exposure unit and Ive got nice screens......


QTX and RLX both good stuff. RLX is more forgiving to room light so you don't have to be so careful about walking across a room with it.

[shorelinegraphix]

your exposure time is to short or your exposure unit is weak/junk. you could expose it in the sun in about 1-3 minutes. my exposure unit is a work horse 1000 point and burns screens in one minute.

[BSTCLOTHING]

My first thought might be underexposure. After reading all the comments here you have enough info to test a couple things. Here is my contribution. Two things, maybe you are holding the pressure washer too close to the screen while washing out? And also if there is not a proper seal against the glass and its getting light where it shouldn't therefore exposing part of the image. Then when you go to wash it out you spend a lot of time trying to get those accidentally exposed areas, therefore saturating the emulsion so much that it swells and falls off the screen. Just things that i have experienced.