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screen printing => Waterbase and Discharge => Topic started by: mimosatexas on April 27, 2014, 02:40:30 PM
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So I have tried all sorts of stuff with my Aquasol HVP and nothing is helping it stand up to the CCI discharge white for longer than a few dozen prints. I bought SP1400 locally to try instead, added diazo, and began testing. So far it is also failing pretty miserably, though the detail it holds compared to the AqHVP is surprisingly good. I am holding literally every single dot my printer outputs at 55lpi.
Here is what I have tested so far:
Exposing 225S and 160 mesh, coated 2/1 for 4:45 and 5:20 respectively, based on a stouffer step test to hard 7 soft 8 for each mesh count. Both are yellow mesh.
I have tried no post exposure, 10 minute post exposure, 10 minute post exposure with MS hardener. I have also tried, quick air dry by fan and overnight dry in the dry box, both post exposure. All screens are dried overnight after coating.
No matter what, the CCI is making the emulsion tacky, then breaking down, then when washing out almost every dot under 5% is simply going away. Clearly the emulsion is breaking down. I have done 30-50 strokes on each test.
I have done similar tests with Matsui and Magna discharge whites and even just exposed, air dried, and put on press the SP1400 is holding up perfectly fine for 50 prints with those.
Any ideas? I will likely be getting one of the CCI discharge emulsions next, but I really don't understand why it is so much more caustic than the matsui and magna that I have one hand.
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So I have tried all sorts of stuff with my Aquasol HVP and nothing is helping it stand up to the CCI discharge white for longer than a few dozen prints. I bought SP1400 locally to try instead, added diazo, and began testing. So far it is also failing pretty miserably, though the detail it holds compared to the AqHVP is surprisingly good. I am holding literally every single dot my printer outputs at 55lpi.
Here is what I have tested so far:
Exposing 225S and 160 mesh, coated 2/1 for 4:45 and 5:20 respectively, based on a stouffer step test to hard 7 soft 8 for each mesh count. Both are yellow mesh.
I have tried no post exposure, 10 minute post exposure, 10 minute post exposure with MS hardener. I have also tried, quick air dry by fan and overnight dry in the dry box, both post exposure. All screens are dried overnight after coating.
No matter what, the CCI is making the emulsion tacky, then breaking down, then when washing out almost every dot under 5% is simply going away. Clearly the emulsion is breaking down. I have done 30-50 strokes on each test.
I have done similar tests with Matsui and Magna discharge whites and even just exposed, air dried, and put on press the SP1400 is holding up perfectly fine for 50 prints with those.
Any ideas? I will likely be getting one of the CCI discharge emulsions next, but I really don't understand why it is so much more caustic than the matsui and magna that I have one hand.
The reason we switched over to the NOVA emulsion is because it had ZERO problems like this. We use CCI White discharge more than any other ink in our shop, so for us it was worth the extra price to have no problems with screens.
sorry that doesn't help you now, but at least it's something to think about. I'm going to try some of the CCI emulsion this summer as well.
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That does sound weird.....have you tried the CCI WR-14 others here have suggested this & we have had good results with it across several WB & DC inks runs 600pic. & up. With hardener longer runs like 1200, wash out & use again. Quick burn times for us too. If we rush it doesn't seem to last as long though. This is just us & I'm sure others have had different results.
Murphy37
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I long ago stopped caring about price for products that "just work". I'll pick up some Nova asap. Do you do anything special or just expose and go? If I can cut out the post expose, overnight drying, hardener, etc. it would be awesome. I just want to speed up turnaround on screens while using the CCI if possible. It has such better dry in time and is so creamy out of the can vs the Matsui. It is not quite as white/opaque, but those factors make it worth using to me.
I'll pick up some of the WR-14 as well. Does it require any of the post expose, overnight drying, hardener, etc.? Most of my runs are around 100-250 right now. The AQHVP holds up fine at these quantities with post expose and hardener when using Matsui, but it fails on press in like 25 prints with the CCI. The SP1400 is failing on press at around 25 with just expose and go, 30 with post-expose, and 50-55 with post-expose and hardener. All are losing every dot under 5-10% on washout. All of this is unacceptable.
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I long ago stopped caring about price for products that "just work". I'll pick up some Nova asap. Do you do anything special or just expose and go? If I can cut out the post expose, overnight drying, hardener, etc. it would be awesome. I just want to speed up turnaround on screens while using the CCI if possible. It has such better dry in time and is so creamy out of the can vs the Matsui. It is not quite as white/opaque, but those factors make it worth using to me.
I'll pick up some of the WR-14 as well. Does it require any of the post expose, overnight drying, hardener, etc.? Most of my runs are around 100-250 right now. The AQHVP holds up fine at these quantities with post expose and hardener when using Matsui, but it fails on press in like 25 prints with the CCI. The SP1400 is failing on press at around 25 with just expose and go, 30 with post-expose, and 50-55 with post-expose and hardener. All are losing every dot under 5-10% on washout. All of this is unacceptable.
This is what we do with the nova
1. open diazo
2. pure in WARM distilled water, about 1/4 of the container
3. shake diazo for about 5 mins
4. open up Nova Gallon
5. Mix in Diazon
6. Let sit for 2 hours
7. Coat screens 205 and under 1 pass on outside and inside, 230 and over, one pass on the substrate side, with the round edge of the scoop coater
*we might change step 7 to do it 1 pass on the outside and inside on all screens as we've been moving alot of our darker discharges to higher meshes.
No hardener. We post harden in the sun or in our exposure unit if we have a really big run.
We've been using the emulsion for about 2 years and have run into only one issue, when the temps. were changing alot we got a bad 5er from Xenon. that messed up some screens, but they were great about it. You can also tell the difference when coating right away.
Also we only had one screen breakdown, and that was earlier this week. For some reason the same ink/image broke down 3 different screens all coated the same way...so i'm looking into that this week.
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We have run orders that size with no post-exposer or hardener but dry in the sun so if you don't have the sun you might want to post-expose. It seems like a good emulsion for lower wattage exposure units. But that's just us......also l have had good luck with being able to wipe the screen & things not being soft.
Murphy37
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I still need to try the Nova & the few times I have talk to Sonny he is super helpful and a very friendly guy.
Murphy37
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Nova could well be as close to bulletproof as it gets. Hard telling for sure as we have 3 more to test before concluding. Yes the cost is high and burn times are epic next to HVP but it sure is nice to be able to just wipe a DC screen with halftones on press after 100s or 1000s of DC/WB prints and not be scared shitless that the stencil is going to delaminate. We add all the water to the diazo (too dry here to do the 1/4 or 1/2 water in the bottle, the emulsion will crack without enough water in there) and do pretty much like Eric. Still narrowing down the coating thing but coating with it kinda throws out all the normal rules. Doing coats from the substrate side only right now, considering drying ink side down for a better emulsion "sandwich" *another topic really. It's not an emulsion for thicker stencils due to it's viscosity, flows too much after coating. We still have to harden Nova but don't need to post expo it.
You shouldn't be seeing these issues with the HVP. It's not as tough as some other emulsions but is good for many prints, it tends to just squeak by for most longer runs but hangs tough through most. First thing I would look at is drying, the screens need to be uber dry before coating, after coating before shooting, after shooting. Like bone dry. If screens are in an environment where they could absorb ambient humidity before going to press, cook 'em again before going to print.
Do you have diazo in the HVP? Are you coating that 225 with the thin edge of the coater? What do you burn with?
I would def talk to Alan at Murakami as well, he's to Murakami what Richard Greaves was to Ulano in the past and has a very solid understanding of the emulsion all the way to a production level.
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No diazo in the HVP. Screens are as dry as I can make em at each step of the process (in a drying cabinet with dehumidifier and lots of airflow over night). I am using the monster max coater, and both sides are rounder than the sharp side on most coaters, but sharper than the round side, if that makes sense. I am burning with a 1k MH diy unit.
The part that is baffling to me is the difference between the CCI and the Matsui/Magna/Sericol/Jantex discharge inks and TW/Speedball/etc waterbased inks I've used without issue on the HVP (post exposed and hardened). Nothing eats at it like the CCI...
The SP1400 with diazo only held up marginally better.
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Glad to help any who need it. Nova is $82 per gallon. 404-895-1796
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No diazo in the HVP. Screens are as dry as I can make em at each step of the process (in a drying cabinet with dehumidifier and lots of airflow over night). I am using the monster max coater, and both sides are rounder than the sharp side on most coaters, but sharper than the round side, if that makes sense. I am burning with a 1k MH diy unit.
The part that is baffling to me is the difference between the CCI and the Matsui/Magna/Sericol/Jantex discharge inks and TW/Speedball/etc waterbased inks I've used without issue on the HVP (post exposed and hardened). Nothing eats at it like the CCI...
The SP1400 with diazo only held up marginally better.
it sounds like you are not properly exposing. After you burn the screen leave it out in the sun for a while and test again. It should be nice and sunny just to make sure you are getting enough UV. If the results are the same it's the exposure. . .
pierre
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Murakami recommends adding the diazo and using either one of their hardeners for discharge/waterbase. When coating screens for dc/wb we use a thin 1 over 1 coat of emulsion, sharp edge of the coating trough. Try a thinner stencil, you may have a lot of moisture content in the emulsion, even with an environmentally controlled drying area, with your stencil thickness. HVP is 42% solids, it can make a thick stencil. With the long exposure times you posted I would be concerned with what type of light source you are using. HVP is a pure photopolymer so it will benefit from post exposure, but if the initial exposure is insufficient then you will losing emulsion on the squeegee side of the screen during washout, which could lead to delamination.
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What's your ambient humidity like? I'm guessing you're in Texas somewheres, and that ranges from bone dry to bayou.
Completely dry emulsion, both pre and post exposure is extremely important.
What kind of exposure unit? With SP1400 we're at roughly those times, and maybe longer (LU's, but they are roughly 1 second)
on a 3140 and a Photosharp. (1200 watt MH)
When we used to use Aquasol HV we'd post expose, wipe on hardener on long runs, and use the same screens several days in a
row on super long discharge runs. Never gave us any issues.
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Try WR-14 or TX-Discharge for short to medium run discharge ink jobs. Try our C-Tex for long run waterbase / discharge runs for bullet proof stencils. When used with our PermX hardener we have had customers print 150,000 imprints of white discharge ink. We also make a reclaimable hardener called HardenX. The key to hardeners is to let them sit after you wipe it on. Over night dramatically increases the resistance, than just wiping it on and going to press. The hardeners need time to crosslink and it takes hours to do this. Try that next time you make a waterbased screen. Put the hardener on the night before.
Let me know if you have any questions.
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Try WR-14 or TX-Discharge for short to medium run discharge ink jobs. Try our C-Tex for long run waterbase / discharge runs for bullet proof stencils. When used with our PermX hardener we have had customers print 150,000 imprints of white discharge ink. We also make a reclaimable hardener called HardenX. The key to hardeners is to let them sit after you wipe it on. Over night dramatically increases the resistance, than just wiping it on and going to press. The hardeners need time to crosslink and it takes hours to do this. Try that next time you make a waterbased screen. Put the hardener on the night before.
Let me know if you have any questions.
We've never waited long after applying hardener before going to press and we've had mixed results so this will probably help us tremendously. There have been times where we've been on press within 5 minutes of applying hardener and only on a few occasions do I remember having the screen ready a full day before the run. It makes perfect sense but I never really put much thought into it needing time for crosslinking. With that said we have tried out a few DC/WB emulsions but have settled on HVP due to it working well with plastisol and others' having success with long DC runs without diazo. We've done a few runs of 1-2K with the stencils holding up and post exposed along with hardener, no diazo. I'd love to have an emulsion that we could use for all our plastisol as well as DC jobs and it not need all the extra work prepping the screen but the HVP has done well for us after we figured out the exposure issues. We were underexposing and couldn't really figure it out since all the physical signs of underexposure were not there at all, they seemed like they were bordering on overexposure if anything. After learning the exposure times needed the HVP with hardener holds up to whatever we throw at it.
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Try WR-14 or TX-Discharge for short to medium run discharge ink jobs. Try our C-Tex for long run waterbase / discharge runs for bullet proof stencils. When used with our PermX hardener we have had customers print 150,000 imprints of white discharge ink. We also make a reclaimable hardener called HardenX. The key to hardeners is to let them sit after you wipe it on. Over night dramatically increases the resistance, than just wiping it on and going to press. The hardeners need time to crosslink and it takes hours to do this. Try that next time you make a waterbased screen. Put the hardener on the night before.
Let me know if you have any questions.
What is the difference btw WR-14 and C-Tex? Does C-Tex require a longer exposure time? We currently use WR-14 with HardnerX and have had issues on longer runs at 2,000 or so impressions.
Thanks
Chris
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...since we have a tech on the thread, should the hardener be applied while screen is still wet of after drying? Does it make a difference?
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Hello Everyone,
Switching emulsions is not the answer. The issue is the light and exposure time. HVP should be prepared as follows. While I had my shop I ran 290,000 units on one set of screens using basically the same emulsion Aquasol TS, HVP is just a higher viscosity.
So here is the way to prepare a bullet proof screen:
1. Add 8 grams of diazo to HVP. This aids in water resistance. Without it you need a 5k or higher metal halide with an excellent histogram, or spectral output in UV wavelengths, not the white light portion.
2. Dry it overnight, if it is raining you may want a dehumidifier in the room, or put back in a hot box at 100 degrees for 15 minutes prior to exposure. If you have a hot box an hour or more is necessary to dry the screen, if wet 3-4 hours depending on humidity. Here in Socal, 1 hour at 30% humidity. The lower the mesh count the more time needed.
3. Can you over expose on your unit? If your DIY Metal Halide cannot overexpose a 110T screen it may not have enough UV in it. Just because you get an image does not mean you achieved a durable exposure. It's not how fast you can expose, its' how well you can expose. Images break down, Good exposures do not. So push the time as far as you can before overexposing. You must have your exposure time just below overexposure for discharge, plastisol can get away with underexposure on short runs.
4. During development try to rub off the details while the screen is wet. If you can rub off the details the emulsion is underexposed, or you aren't using a good degreaser. Go back and do a step test with your film. Stouffer guides are density strips with good density, but they are not your films. You need to find out how much light you can use, not how little you can use. 90-95% of the strength comes from the initial exposure, everything else is a band aid. Take an unexposed screen out into the sun for the same amount of time as your exposure unit. The inside will be squeaky clean exposed. No slime at all. More on the sun in a minute.
Here is the URL to perform a step test. http://murakamiscreen.com/wp-content/uploads/2012/07/Step-Test-Instructions.pdf (http://murakamiscreen.com/wp-content/uploads/2012/07/Step-Test-Instructions.pdf)
5. Once you find a step test time you like, then throw on the stouffer density strip after the step test with the new time to see what it reads so you can hit that hardness level again and again. Remember, if you can rub off details during development the exposure is inadequate, or the lamp does not have good spectral output in the 350, 380, and 420 nanometer wavelengths, these are the key wavelengths. White light doesn't count too much. Its the UV at the nanometers listed that need to be bright and have the most strength.
6. Develop the screen as always. Any slime? It will breakdown.
7. IF there is no slime, squeegee off the excess water and then you can apply MS hardener. The risk you take applying hardener when wet is you can wipe soft emulsion back in the image and it will block the open areas. That is the main reason to dry the screen first. However if you wipe the inside of the screen and don't see emulsion color you can apply MS hardener to a wet screen. If you do see emulsion color put it out in the sun and post expose. SBQ remains sensitive to post exposure and the sun will aid DIY exposure units to achieve a better exposure. The strongest screens will come from an 8k metal halide with a fresh bulb. Tons of UV, all the molecules line up and cross link completely, much stonger molecular bonds are formed.. (This never happens on 1k or DIY units FYI.) So dry in sun, squeegee side towards the sun, then apply MS hardener, or if you want to cut out the mesh and emulsion use Murakami Hardener A&B to create a semi-permanent screen, you still need great exposure, hardeners put a skin on the surface of the emulsion. A weak exposure inside the hardened surface is still a weak exposure.
9. So how does a DIY shop get really strong discharge screens if none of the above tips still won't prevent breakdown? Use a sun exposure unit between 10 am and 2pm in full sunlight. This is a spring, summer, early, fall exposure since we need sunlight that would give you a sunburn. Winter, only in the deep south.
Email me at abuffington@murakamiscreen.com for a PDF drawing of a sun exposure unit that is an enclosed box rather than the description below.
Here is how to do it without the drawing. Get a window frame that fits over your screen. Get a piece of 4 inch upholstery foam from an old cushion that fits within your screen and will be flat against the inside of the screen with the window frame resting on it with the frame outside the screen frame so that only glass is resting on the screen frame. Cover foam in black t-shirt fabric, cut to size and spray adhesive to adhere. Place foam on top of flat small cart with wheels. Place screen with art film in position over the foam. Place window frame on top of screen. Place some weight on the frame, or if it presses the art flat against the emulsion you don't need more weight. If you do, quart containers w water work. Roll cart out in the sun at noon. As soon as it hits the sun start a timer and expose HVP for 60-90 seconds, it can be as low as 30! depending on UV in your area. If you have added diazo you will see the emulsion turn dark pink with HVP. You may need to experiment with time. SP-1400 would provide more latitude and a greater emulsion color change and exposure would be in the 2 minute range.
Roll cart back into safe light area and remove and develop. This screen will outdo any DIY. I printed for Disney for 3 years using a large table with 4 of these setups and shot screens like mad from 11-2 before buying a 7500 watt lamp. The sun can create one strong screen. Clouds don't help, clear uninterrupted sun.
The sun is a 23k exposure unit minimally. I had to pull my light meter out of the sun as it was still going up at this level!
Thanks to all my competitors who feel selling a different emulsion is the answer, obviously not the answer to his issues.
Al
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Best we've found for applying hardener (Murakami MS, your results may vary):
- Roll it on while the screen is damp, just after resolving.
- Let it soak in as long as possible without allowing the hardener to dry in the image area.
- Shoot some clean, compressed air through the image area to clear out the hardener there.
- Cook the screens again.
CCI Tech is right on the money, overnight will give you significantly better results. In a rush? Cook the screen for an hour at 90˚F or so before going to press.
I got us a 24" wide roller and matching bucket just for doing this and am all kinds of screen print production nerd excited about getting this going faster. Dip the roller in the bucket, roll it on both sides. Hardening gets done right in the clean booth after resolving. Makes it a very minimal step to add when done this way. We found we could eliminate either post expo or hardening but not both so I found a way to make hardening go really fast.
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I do have stouffer tests and use them. I am drying overnight in a hotbox with a dehumidifier. I have no slime after a 4 minute fully submerged dunk and washout. I cannot rub off detail and even pin point pressure washing requires multiple seconds to knockout low percentage dots. Im confident the exposure is fine.
Im having literally no breakdown using every other brand of discharge i have access to, including 4 other whites. i've been using matsui discharge almost everyday for a few years without emulsion issues.
My question isnt why my screens are failing when using discharge...because they arent. My question is why are they failing almost instantly with cci white exclusively. I was hoping someone else had seen similar issues with that specific ink or could explain what makes it more caustic than every other brand.
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My question isnt why my screens are failing when using discharge...because they arent. My question is why are they failing almost instantly with cci white exclusively. I was hoping someone else had seen similar issues with that specific ink or could explain what makes it more caustic than every other brand.
I was hoping that the CCI TECH would have had something to say about this?
Murphy37
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I do have stouffer tests and use them. I am drying overnight in a hotbox with a dehumidifier. I have no slime after a 4 minute fully submerged dunk and washout. I cannot rub off detail and even pin point pressure washing requires multiple seconds to knockout low percentage dots. Im confident the exposure is fine.
Im having literally no breakdown using every other brand of discharge i have access to, including 4 other whites. i've been using matsui discharge almost everyday for a few years without emulsion issues.
My question isnt why my screens are failing when using discharge...because they arent. My question is why are they failing almost instantly with cci white exclusively. I was hoping someone else had seen similar issues with that specific ink or could explain what makes it more caustic than every other brand.
We use CCI D white and HVP emulsion and have used the Matsui and Rutland products recently and I can see what you're talking about but our screens hold up just fine over a long run. They do look to be breaking down faster with the CCI product initially but they end up holding up for hundreds to 1-2K prints. I have used the Matsui for a long run and I couldn't tell the screen was any worse looking at the end as they are at the end of a CCI run. It does seem that CCI is harder on the emulsion in the beginning and with that combo we had to have a good stencil to go to press but we've had the Jantex ink attack screens with the quickness too so it's not just an ink issue in my opinion. It makes sense to change emulsions if you can't get the screen exposed enough to hold up to the CCI inks but you could do what we did and put a tad bit more exposure time on the HV. It's possible that your light source isn't capable of handling a harsher ink and the emulsion change might be your only option other than using the sun. I'm thinking I might try to expose a few screens with the sun since I've never really tried to do it.
One thing Alan said earlier (in a great post by the way) was to look for the slime and if it's there, you will def see breakdown and that's a no doubter, but I'd like to mention, even if it passes the slime test, you could see breakdown. When we were struggling with DC screens, there was no doubt in my mind that we were exposing long enough because there was not one single physical sign of a weak stencil until you got about 50 prints into a run and the screen would break down. I was doing the exposure tests and we were well over the safe level for exposure and still had breakdowns, and only when I took it to an extreme level of exposure did the screens turn bullet proof. Thing is I KNEW they weren't underexposed because I've done this thousands and thousands of times and know an underexposed screen when I see one, but for DC, they were underexposed despite having no signs of it. It was embarrassing for me to admit to the guys I was underexposing the screens and the ink wasn't the problem like I was 100% sure of at the time.
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I was hoping someone else had seen similar issues with that specific ink or could explain what makes it more caustic than every other brand.
Have you tried lowering the percentage of activator?
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I have tried it even without activator, same issues.
I'm going to try pumping up the exposure time a bit with the SP1400. I really can't push my HVP exposure much further without seeing more loss on the smallest dots. I was actually really surprised by how many dots I was losing with my standard step tested exposure time for HVP vs the SP1400. I was probably losing the bottom 5% on HVP and not seeing loss at all with the SP1400.
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The pigments are the main aggressor. Most experience this with WB black which uses carbon (among other elements) for instance. Warm shade reds can cause issues. Its mostly the non-organic pigments found in these inks that causes this. Titanium in whites, etc
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I have tried it even without activator, same issues.
I'm going to try pumping up the exposure time a bit with the SP1400. I really can't push my HVP exposure much further without seeing more loss on the smallest dots. I was actually really surprised by how many dots I was losing with my standard step tested exposure time for HVP vs the SP1400. I was probably losing the bottom 5% on HVP and not seeing loss at all with the SP1400.
rather than pushing, try taking them out and leaving in the sun after rinse.
pierre
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I have tried it even without activator, same issues.
I'm going to try pumping up the exposure time a bit with the SP1400. I really can't push my HVP exposure much further without seeing more loss on the smallest dots. I was actually really surprised by how many dots I was losing with my standard step tested exposure time for HVP vs the SP1400. I was probably losing the bottom 5% on HVP and not seeing loss at all with the SP1400.
Holding your dots has more to do with the darkness of your film then the emulsion, exposure time, exposure unit or wash out pressure. If your film is too light you will not be able to expose your film long enough with out hardening the design area of the screen. If your losing dots and not getting a good strong stencil then your film is the problem area. If you have dark film you can expose a screen for way longer. You will have a easier screen to wash out.