Roq auto newbie, experiencing emulsion breakdown with discharge / wb

[Raw Paw]

Hello TSB,

We recently made the upgrade to a 8/10 Roq You.  Already getting used to things, but quite a steep learning curve.  After 15 years of manual printing, a lot of the things that simply worked before now need to be reconsidered.  I have attached some photos of recent screens we have made trying to troubleshoot the problems.

We almost immediately started experiencing screen breakdown problems when we did our first discharge run.  After doing some research on TSB, I found the way we had been coating and exposing screens will simply not work moving forward.  The way I have coated every screen for 15 years was 1 squeegee side, 1 shirt side, then a hard scrape squeegee side, all with the hard edge.  We have always used ProChem TX-Discharge Emulsion with no breakdown problems, thousands of shirts with the same screen, multiple setups, ect, but this was hand printing.  Exposure was 60 seconds in the Vastex LED E-2000, never messed with the exposure strip because we never had emulsion breakdown and could hold all detail.

After experiencing emulsion breakdown (mainly using CCI discharge white, but I have also noticed breakdown occurring with wb inks), I did a lot of reading on tsb, I have changed our coating process to the standard 1-1, and tried out two new emulsions - SAATI Textil PHU 2 and Murakami SP-1400.  We also got a dehumidifier.  I wasn't really happy with our initial results from PHU 2, however SP-1400 seems promising.  I found using the exposure strip we needed to increase our exposure time to around 90+ seconds (SP-1400 emulsion on T-mesh 150, with Vastex E-2000 exposure).  I ran 105 discharge white on gildans yesterday w/ 2 print strokes and made it through the run, the screen began breaking down near the edges of the squeegee / pallet about a third or halfway through the run, but no ink fully broke through the stencil, which is a step in the right direction.

A few notes here - SP-1400 is a diazo emulsion, and from what I have gathered, this emulsion type doesn't benefit from post exposure.  Screen hardener is recommended for larger discharge / wb runs, however from what I have seen on here, not at all necessary if you have achieved adequate exposure.  If I can get the SP-1400 to work w/out post exposure and hardener, that would be ideal, considering the prolonged exposure time.  I have read posters on here claiming that the LED exposure units aren't quite as proficient as single light source MH lamps, and don't have the light strength to fully crosslink the emulsion.  Hoping this isn't the case, but it doesn't seem to be, I know we can figure this issue out with our current exposure set up.  PHU 2 on the other hand is a pp emulsion, meaning it exposes faster.  However our screen broke down quicker, and I couldn't expose small dots as well as the SP-1400 or Prochem TX-Discharge emulsion.  The next brand I want to experiment with is Murakami T9, but SP-1400 seems like it will work well enough for now to establish a constant.

When initially describing these problems to our local supplier and Roq tech, we were recommended to just post harden the screens in the sun and use hardener.  We did both of these and didn't notice any aide in the breakdown (this was using our old coating technique and Prochem TX-Discharge emulsion).  Since adjusting coating technique, emulsion, and exposure time, I feel we are getting closer.  This brings me to my next question..  How much pressure is too much?  I have been finding 25-35 psi is adequate for plastisol, but I am struggling to get a fully saturated print with that pressure for wb / discharge.  After some research and trying things out, I am finding a squeegee angle of 20*, pressure of 55-60 psi, the squeegee nearly at 0, and a slow squeegee stroke produces a beautiful print.  This is using the standard squeegees that came with the press.  If I am still having issues achieving proper saturation, I will lower the floodbar so it is loading the screen with ink between squeegee passes.  However, I worry that I am using too much pressure, and squeegee contact, will accelerate screen breakdown, as well as mess up our squeegees.  To Roq users out there, do those squeegee settings seem appropriate?  Also, after a large discharge run, after cleanup, does your screen look brand new again?  Or does the emulsion change appearance based on where the squeegee traveled and ink type used?  My rule is if I notice the emulsion breaking down mid run whatsoever, I need to wrap it up and shoot another screen, bc the issue never gets any better once it's started.

Another thing to try out is taping the edge of the screen, where the edge of the squeegee makes contact with the screen, to prevent the abrasion which speeds up breakdown.  However, I know tons of users here are completely tape free.  I would love to figure out how to get an initially adequate exposure, rather than add tons of taping, post exposure, and screen hardener processes.  We have lots of clients with legacy screens, so really, I need to be able to make screens that survive 5+ production runs.

Thank you all for reading my long and rambling post, I apologize if it was too detailed, but I wanted to be as specific as possible.  If anyone has any tips or ideas our team would really appreciate it!!!

Attachments - green screen is SP-1400, red screen is PHU 2

[Rockers]

Hello TSB,

We recently made the upgrade to a 8/10 Roq You.  Already getting used to things, but quite a steep learning curve.  After 15 years of manual printing, a lot of the things that simply worked before now need to be reconsidered.  I have attached some photos of recent screens we have made trying to troubleshoot the problems.

We almost immediately started experiencing screen breakdown problems when we did our first discharge run.  After doing some research on TSB, I found the way we had been coating and exposing screens will simply not work moving forward.  The way I have coated every screen for 15 years was 1 squeegee side, 1 shirt side, then a hard scrape squeegee side, all with the hard edge.  We have always used ProChem TX-Discharge Emulsion with no breakdown problems, thousands of shirts with the same screen, multiple setups, ect, but this was hand printing.  Exposure was 60 seconds in the Vastex LED E-2000, never messed with the exposure strip because we never had emulsion breakdown and could hold all detail.

After experiencing emulsion breakdown (mainly using CCI discharge white, but I have also noticed breakdown occurring with wb inks), I did a lot of reading on tsb, I have changed our coating process to the standard 1-1, and tried out two new emulsions - SAATI Textil PHU 2 and Murakami SP-1400.  We also got a dehumidifier.  I wasn't really happy with our initial results from PHU 2, however SP-1400 seems promising.  I found using the exposure strip we needed to increase our exposure time to around 90+ seconds (SP-1400 emulsion on T-mesh 150, with Vastex E-2000 exposure).  I ran 105 discharge white on gildans yesterday w/ 2 print strokes and made it through the run, the screen began breaking down near the edges of the squeegee / pallet about a third or halfway through the run, but no ink fully broke through the stencil, which is a step in the right direction.

A few notes here - SP-1400 is a diazo emulsion, and from what I have gathered, this emulsion type doesn't benefit from post exposure.  Screen hardener is recommended for larger discharge / wb runs, however from what I have seen on here, not at all necessary if you have achieved adequate exposure.  If I can get the SP-1400 to work w/out post exposure and hardener, that would be ideal, considering the prolonged exposure time.  I have read posters on here claiming that the LED exposure units aren't quite as proficient as single light source MH lamps, and don't have the light strength to fully crosslink the emulsion.  Hoping this isn't the case, but it doesn't seem to be, I know we can figure this issue out with our current exposure set up.  PHU 2 on the other hand is a pp emulsion, meaning it exposes faster.  However our screen broke down quicker, and I couldn't expose small dots as well as the SP-1400 or Prochem TX-Discharge emulsion.  The next brand I want to experiment with is Murakami T9, but SP-1400 seems like it will work well enough for now to establish a constant.

When initially describing these problems to our local supplier and Roq tech, we were recommended to just post harden the screens in the sun and use hardener.  We did both of these and didn't notice any aide in the breakdown (this was using our old coating technique and Prochem TX-Discharge emulsion).  Since adjusting coating technique, emulsion, and exposure time, I feel we are getting closer.  This brings me to my next question..  How much pressure is too much?  I have been finding 25-35 psi is adequate for plastisol, but I am struggling to get a fully saturated print with that pressure for wb / discharge.  After some research and trying things out, I am finding a squeegee angle of 20*, pressure of 55-60 psi, the squeegee nearly at 0, and a slow squeegee stroke produces a beautiful print.  This is using the standard squeegees that came with the press.  If I am still having issues achieving proper saturation, I will lower the floodbar so it is loading the screen with ink between squeegee passes.  However, I worry that I am using too much pressure, and squeegee contact, will accelerate screen breakdown, as well as mess up our squeegees.  To Roq users out there, do those squeegee settings seem appropriate?  Also, after a large discharge run, after cleanup, does your screen look brand new again?  Or does the emulsion change appearance based on where the squeegee traveled and ink type used?  My rule is if I notice the emulsion breaking down mid run whatsoever, I need to wrap it up and shoot another screen, bc the issue never gets any better once it's started.

Another thing to try out is taping the edge of the screen, where the edge of the squeegee makes contact with the screen, to prevent the abrasion which speeds up breakdown.  However, I know tons of users here are completely tape free.  I would love to figure out how to get an initially adequate exposure, rather than add tons of taping, post exposure, and screen hardener processes.  We have lots of clients with legacy screens, so really, I need to be able to make screens that survive 5+ production runs.

Thank you all for reading my long and rambling post, I apologize if it was too detailed, but I wanted to be as specific as possible.  If anyone has any tips or ideas our team would really appreciate it!!!

Attachments - green screen is SP-1400, red screen is PHU 2

we are using the same exposure unit, with T9. No real issues. We always use tape on the squeegee side of the screen. But even if we wouldn’t or images would not break down during a 105 pcs run. Have you checked if all the bulbs on the light strips of your exposure units are still functioning? We had to replace our light strips a couple of years ago due to that issue. They were nowhere near 50,000 hrs of usage.

[Raw Paw]

we are using the same exposure unit, with T9. No real issues. We always use tape on the squeegee side of the screen. But even if we wouldn’t or images would not break down during a 105 pcs run. Have you checked if all the bulbs on the light strips of your exposure units are still functioning? We had to replace our light strips a couple of years ago due to that issue. They were nowhere near 50,000 hrs of usage.

Ok, that is reassuring, thank you for putting my mind to rest.  Glad our exposure unit will cut it.  I will test out T9 for sure, and check the bulbs.  Any reason you don't use SP-1400?  And am I using an excessive amount of air pressure?  Thanks dude

Edit to add - are you having to re-expose / sun dry the T9, or use hardener to prevent breakdown, or are you achieving a durable stencil that will last up to 1000 prints just with initial exposure?

[Rockers]

we are using the same exposure unit, with T9. No real issues. We always use tape on the squeegee side of the screen. But even if we wouldn’t or images would not break down during a 105 pcs run. Have you checked if all the bulbs on the light strips of your exposure units are still functioning? We had to replace our light strips a couple of years ago due to that issue. They were nowhere near 50,000 hrs of usage.

  Any reason you don't use SP-1400?  And am I using an excessive amount of air pressure?  Thanks dude

Edit to add - are you having to re-expose / sun dry the T9, or use hardener to prevent breakdown, or are you achieving a durable stencil that will last up to 1000 prints just with initial exposure?

Sp-1400 makes recycling screens a painful experience if you ask me.
With T9 we rarely use hardener. We rarely use hardener period. Sometimes we make screens for other shops or hobby prijnters. We then use hardener as I don`t know how what they do to their screens and I don`t want them to come back like little cry babies.

[Raw Paw]

Brilliant, we will order some T9 tomorrow morning and shoot our screens for the week with it.  Thank you

[ericheartsu]

All of your pictures make it seem like the emulsion is not properly cross linked.

Do you have a stouffer strip? If not, can you get one?

I see you have a stouffer strip, and it's clear you are not hitting a solid seven. I'd increase your exposure time.

[Raw Paw]

All of your pictures make it seem like the emulsion is not properly cross linked.

Do you have a stouffer strip? If not, can you get one?

I see you have a stouffer strip, and it's clear you are not hitting a solid seven. I'd increase your exposure time.

Thanks Eric.  To pass the stouffer test, should the 7 not wash out at all, even a little bit?  Ideally, should 8 and 9 still be a properly exposed screen, and what should those look like?

I've been manual printing 15 years and never imagined I had so much more to learn..  Sure beats printing 500 6 colors a day by hand though

[ericheartsu]

All of your pictures make it seem like the emulsion is not properly cross linked.

Do you have a stouffer strip? If not, can you get one?

I see you have a stouffer strip, and it's clear you are not hitting a solid seven. I'd increase your exposure time.

Thanks Eric.  To pass the stouffer test, should the 7 not wash out at all, even a little bit?  Ideally, should 8 and 9 still be a properly exposed screen, and what should those look like?

I've been manual printing 15 years and never imagined I had so much more to learn..  Sure beats printing 500 6 colors a day by hand though

i believe so. but i'd call Saati, or richard grieves.

[Steve12Lowry]

All of your pictures make it seem like the emulsion is not properly cross linked.

Do you have a stouffer strip? If not, can you get one?

I see you have a stouffer strip, and it's clear you are not hitting a solid seven. I'd increase your exposure time.

Thanks Eric.  To pass the stouffer test, should the 7 not wash out at all, even a little bit?  Ideally, should 8 and 9 still be a properly exposed screen, and what should those look like?

I've been manual printing 15 years and never imagined I had so much more to learn..  Sure beats printing 500 6 colors a day by hand though

Check out the attached file for a quick tutorial.

[Raw Paw]

Check out the attached file for a quick tutorial.

Thanks Steve!!  That is very helpful

[Raw Paw]

Hello, warriors of the print realm.

I wanted to give an update...  I switched to T9, ran a  ton of tests, and found a suitable exposure time.  I did the step test like described above with a solid line gradient covering the print area, and another one with gradients of my normal halftone and dither patterns.  Ran 10-90 second steps, washed out the screen, narrowed it down to a range of 32-64, and narrowed down my exposure time to 52 seconds, as this was the most I could expose the screen without losing my halftone detail after pressure washing.  Then had the idea to just throw these screens on press the following day, and see how they would erode, based on exposure time.  Up to 90 seconds exposure was still eroding the screen, with post exposure.  The screen held up, no ink visibly broke onto the shirt after 100 test prints, but seeing the emulsion visibly erode is panic inducing for me.  Not an option.

So I have been experimenting with post exposing squeegee side in the sun, or post exposing 3x exposure time, to harden the squeegee side.  Drying our coated screens far more thoroughly than before for longer w/ a dehumidifier, higher eom on screens, waiting a day post exposure and completely prepping the screen before printing...  Still experiencing breakdown.  We got through 2 600 piece wb jobs the other day, but only because we were stopping to tape up breakdown, and had to switch out screens halfway through due to breakdown.  With discharge, this problem is even worse. 

Pulled a job today that was experiencing breakdown before I had even really gotten it up and running, and this is after I thoroughly did every step of the process in preparing those screens myself.  I was also experiencing seepage of discharge agent through one of the screens (110), which I had never seen before, and could not remedy on press (apparently due to my improper tape technique I picked up on youtube of taping the underside of the screen).  I'm getting a hard stoffer 7 on all of these screens by the way.  I used a white shirt to check squeegee side of screen for slime, nope.

Two things that I just became aware of that I will implement - drying coated screens squeegee side down (opposite of how I was taught and have heard before), I could see this making a big difference in getting a more solid eom squeegee side.  Only taping on the squeegee side of the screen.  Also getting some rubber tape.  Will look into a specific hardener for T9, and adding Diazo to T9, although that will through off my exposure times, which I am already kinda maxed out in...  Also was made aware that we should curtain off our screen coating room, which is in the same room but removed from the washout area, so we can keep a more constant humidity in there.

Talked to a tech today who basically said (paraphrasing) "you're only going to get so far with discharge / wb screens using an LED exposure unit.  They're fast but don't put out the power to fully cure the emulsion for wb / dc printing.  I got a Metal Halide unit for this very issue."  Basically said we would need to get a drybox and jump through all kinds of hoops to make discharge work w/ the E-2000 exposure unit, and even then breakdown would be common.  I guess not enough power to properly crosslink, hence the necessity for post exposure and hardeners to squeeze out a run.  Post hardening in the sun seems like an absolute necessity.  His real recommendation was get a drybox and new exposure unit, which is like 10k plus right now, and equipment we have absolutely no room for.  It seems like our exposure unit isn't capable of getting a full cross link at first exposure, so without post exposure, the screen is not gonna hold up for a discharge run of more than like 75.  With post exposure, maybe 300. 

So where we are at right now, is we are going to pursue plastisol much more on the roq, until we fully figure this out.  Plastisol works way better with the size of our dryer and cure time, and this screen breakdown issue is simply not a variable in plastisol printing.  We ran a 150 6 color underbased plastisol job when the tech was in the shop with us, and it went off without a hitch, with WB Killer Base as the underbase.  Will continue to run wb and discharge on the manual, where we have never had problems.  We only started printing wb / discharge because we were a manual shop, and the ability to print without an underbase and wet on wet makes a huge difference.  We never had problems with screens then because no human can exert the amount of friction and pressure an auto can, which is literally degrading the emulsion with the friction from the abrasive wb / dc ink.  However the ability to now underbase so much faster allows us to actually explore plastisol printing more practically. 

Will apply all of this new knowledge to making wb and discharge work in the future on the auto.  Apparently T9 is made for LED exposure, and if adding sensitizer to it will make it more water resistant, I'll explore that.  Probably gonna prep 1-2 extra screens for any discharge / wb job I run in the future, as I try to get things to work.  At the moment I've just got to get things out the door without having non stop problems, and plastisol seems like the most logical way forward until I truly get the screen situation in order.  I will update yall when things are in order. 

[Maxie]

There are professionals out there who can help with you.
Saati have great emulsions.    A LED exposure light that is not expensive with exposure times of around 20 sec.
I use PHU and get great results using their smaller lamp.
I also use their chemicals for cleaning and removing emulsion and very happy with the results.

[tonypep]

My experience with wb/discharge emulsions (tried many) and led exposure led to the conclusion that led units do not crosslink the emulsions properly enough for the stencil to be water resistant. After settling on an emulsion, we simply exposed wb screens on the halide unit. Problem solved. So same emulsion, different exposure units for wb vs plastisol. Your results may vary however that was our conclusion.
tp

[ericheartsu]

My experience with wb/discharge emulsions (tried many) and led exposure led to the conclusion that led units do not crosslink the emulsions properly enough for the stencil to be water resistant. After settling on an emulsion, we simply exposed wb screens on the halide unit. Problem solved. So same emulsion, different exposure units for wb vs plastisol. Your results may vary however that was our conclusion.
tp

this is def. a good answer, but when you work with proper emulsion, proper exposure, you can get some really durable screens. We stopped post exposing, and regularly do HSA/DC/WB jobs at 2k + without issues.

[tonypep]

I defer to the new expert at Night Owls......Its been a while since I have been in the wb world and of course, things change. That said. We (most of us perhaps) have only a certain amount of time to test however, that is how we arrive with what works. Carry on all!