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screen printing => Screen Making => Topic started by: rendered.co on July 05, 2018, 01:39:33 PM
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Hello all. We just got our Workhorse LED in today to replace our florescent. Of course it's one of the busiest times of the year for us so we are trying to mitigate the downtime as much as possible. Does anyone use a Workhorse LED with Murakami T9? If so, can you share what times you are getting for exposure/post expose? Also, we've been using diazo for stronger screens when using the fluorescent, but is that needed for the LED? Thanks in advance.
We're hoping to get this dialed in as soon as possible since our screens are taking about 30 minutes a piece right now with exposure+post expose on our fluorescent. I know, it's ridiculous.
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We used T9 for a bit with our workhorse LED, and we were in the 32-37 second range for most screen mesh.
We dont run WB/DC here, so we started going back to the Aquasol HVP, so we dont post expose anything. We just leave it in the sun to dry for a few minutes.
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I'm not using a Workhorse LED, but I'm using a unit similar, also with Pure Photopolymer emulsion. My exposure time for spot color designs is 15 seconds (meshes 110-230). For halftones, 12 seconds (Meshes 158-230). I use almost all 180s mesh, so my exposure times don't vary much. The Workhorse LED is 5 amps I believe. The one I use is 8 amps, so my exposure times might be faster than yours.
A super useful tool I've found is this 21 step exposure calculator from Saati. Here is a link to it: https://www.totalinksolutions.com/saati-21-step-sensitivity-guide.html (https://www.totalinksolutions.com/saati-21-step-sensitivity-guide.html)
I've used this whenever I've switched emulsion, thin to thick thread mesh, exposure units, etc. It takes the bulk of the guess work out. As far as post exposure goes, I just put the screens in the sun for at least 15 minutes. I do a lot of discharge and I see very little breakdown on orders below 300pcs. Haven't ever run a discharge job larger than that, so I have no idea how durable the screen is in the long run.
Hopefully this gives a little bit of insight. If you let the board know what coating method you are using and what kind of thread (s mesh or regular) your screens are, I'm sure someone will have a good answer for you!
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Sweet. Thanks for the info guys. Murakami just reached out to me to give me some more insight, but this is a great start.
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Here's a way that has worked for me, using a Saati 21-step Stouffer strip. It allows you to test several times on a single screen.
-measure the strip
-using black construction paper (or other opaque material), cut 8-10 pieces that are about 3" wider in each direction than the strip. (I actually cut 16-20 pieces, and double stack to ensure opacity.)
-Tape these to the film side of your screen so that they are hinged. Use a smaller piece of tape across from hinge to keep it "closed" when moving the screen.
Then
-fold back one of these "doors," and position the Stouffer strip in the area that the door normally covers.
-Expose the screen at your first test time.
-Pull the screen, removed the strip, close the "door."
-Open the next door, and repeat the process, using your next test time
Repeat until you've tried a different test time behind each door. Work in a pattern, and keep note of your times per door. (I make a sketch of the door layout, and write times on the sketch.)
All open area of your screen will of course be exposed every time - doesn't matter. Wash out the screen, examine each test area, and note which test time got you closest to proper exposure. You may determine the correct time on this screen alone. If not, you should be able to use the closest times to set up a 2nd test to zero in on the proper time.
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Andy....................WHERE IS STEP WEDGE MAN???????
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Andy....................WHERE IS STEP WEDGE MAN???????
He was watching the A's!
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And, here's a link to the pdf that Murakami has prepared about the step wedge exposure 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)
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Ya, I had to snicker a bit.
The Step Wedge process had been discussed for many many years (here and previous places) even though I had not seen mention of it recently until this post. So had to call out for the Super Hero, lol.
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All good info. Thanks everyone. I mainly wanted to see if anyone had a good recommendation of where to start our time for the step calculator. We got a lot of great tips from Al over at Murakami. We are primarily a waterbased shop so emulsion strength is a big factor. My main take aways from the conversation:
Use 4g Diazo for T9 (versus the 8g that usually comes packaged with ours)
Coat 1/1 sharp
Dry screens squeegee side down
With those considerations and all else taken in to account with screen room humidity, etc. we were able to get our 225s exposed at 84 seconds on the Workhorse LED + 50 second post expose. I know it's not as fast as a lot of shops claim, but using the Diazo slows it down a bit. On our fluorescent we were at 17 minute exposure with 15 minute post expose, so it's an amazing improvement. The halftones were really impressive on the LED as well, with almost zero drop out. I did a test run of an equivalent of 200 shirts on the press to make sure we didn't lose any halftones and the screen held up tremendously. Hopefully we're all dialed in for Monday when production starts up again.
Thanks again for all the input!
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Ya, I had to snicker a bit.
The Step Wedge process had been discussed for many many years (here and previous places) even though I had not seen mention of it recently until this post. So had to call out for the Super Hero, lol.
If you're one of us that used a process camera and tray developed film, the Stouffer Step Wedge was an everyday tool. And it worked for screens too!
Steve
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Naw, was kidding from the many posts for Step Wedge posted on the previous sites we used to visit. I never used a camera for film.
However, my dad was a Lithographer and I remember the times he used to tray develop film from a really large camera and do the set up and taping to burn plates.
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Naw, was kidding from the many posts for Step Wedge posted on the previous sites we used to visit. I never used a camera for film.
However, my dad was a Lithographer and I remember the times he used to tray develop film from a really large camera and do the set up and taping to burn plates.
I ran offset for a short while in between real jobs. Little guys, (the small presses were technically called duplicators I seem to recall. They were just starting to use a combo camera and plate maker. I think it was Itek.
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This is what I remember my father running. A Multilith 1250 with a T head to run 2 colors and a one color press. He came from a background of the really big 4 color Harris (I think that was the name) presses before he opened a small Quick Copy 'style' mom and pop store.
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This is what I remember my father running. A Multilith 1250 with a T head to run 2 colors and a one color press. He came from a background of the really big 4 color Harris (I think that was the name) presses before he opened a small Quick Copy 'style' mom and pop store.
I wish I had video. My dad used to print balloons on something like this with the offset roller fully exposed. We (even as kids) would have to time the print and manually spin a balloon at the same speed as roller to get a pretty crappy print. It was awesome at the time though. He started in the late 60's with a deconstructed AB Dick (I think).
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*first actual forum post* WOOO!!
I recently got a sample of T9 and I'm currently calculating burn times. I have PM'd a couple rad dudes on here and I have learned some stuff, so thanks to you guys.
I have a Workhorse Lumitron LED as well so this is like the perfect thread. All I use is waterbase and discharge and I don't the fancy S meshes which seem to be pretty popular among some of yas. Just regular aluminum frames and some newman rollers with white and yellow meshes 86 up to 305.
I was able to find a free exposure calculator on Anthem's site. Do you guys know of anymore free step wedge/exposure calculator vector images I could use with the one I have? I still use films and obviously have the glass on the unit.
I successfully calculated my first 160 (white) mesh the other day and if anyone is familiar with the Anthem calculator (https://www.anthemprintingsf.com/Screen-Exposure-Calculator-s/216.htm (https://www.anthemprintingsf.com/Screen-Exposure-Calculator-s/216.htm)). The last 3 rows looked decent so I got a range of 38-48 seconds. That may seem long to some of you but keep in mind I am still currently using KIWO 300 WR and those burn times are nothing less than 3 solid minutes.
I will still be doing calculations for: 86, 110, 196/200, 230, 280, 305, and maybe 355. Again, NOT s-mesh.
What are your burn times for some of these if you have a Workhorse LED unit?
This T9 is probably going to be a permanent thing once I figure it out especially because of it's durability. I usually have to go through 2 or 3 screens if I'm doing a 1000 pc run. Having been browsing this forum the last week or two, I'm starting to get that I was half-assing some stuff or just plain not doing it right.
I'm fairly new to the screen making process as my forte is just keeping the auto spinning. I recently got a new gig in which I do everything instead of just setting up and printing. I'll probably think of something else I wanted to ask after I post this but...oh well. Thanks in advance for any replies!
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*first actual forum post* WOOO!!
I recently got a sample of T9 and I'm currently calculating burn times. I have PM'd a couple rad dudes on here and I have learned some stuff, so thanks to you guys.
I have a Workhorse Lumitron LED as well so this is like the perfect thread. All I use is waterbase and discharge and I don't the fancy S meshes which seem to be pretty popular among some of yas. Just regular aluminum frames and some newman rollers with white and yellow meshes 86 up to 305.
I was able to find a free exposure calculator on Anthem's site. Do you guys know of anymore free step wedge/exposure calculator vector images I could use with the one I have? I still use films and obviously have the glass on the unit.
I successfully calculated my first 160 (white) mesh the other day and if anyone is familiar with the Anthem calculator ([url]https://www.anthemprintingsf.com/Screen-Exposure-Calculator-s/216.htm[/url] ([url]https://www.anthemprintingsf.com/Screen-Exposure-Calculator-s/216.htm[/url])). The last 3 rows looked decent so I got a range of 38-48 seconds. That may seem long to some of you but keep in mind I am still currently using KIWO 300 WR and those burn times are nothing less than 3 solid minutes.
I will still be doing calculations for: 86, 110, 196/200, 230, 280, 305, and maybe 355. Again, NOT s-mesh.
What are your burn times for some of these if you have a Workhorse LED unit?
This T9 is probably going to be a permanent thing once I figure it out especially because of it's durability. I usually have to go through 2 or 3 screens if I'm doing a 1000 pc run. Having been browsing this forum the last week or two, I'm starting to get that I was half-assing some stuff or just plain not doing it right.
I'm fairly new to the screen making process as my forte is just keeping the auto spinning. I recently got a new gig in which I do everything instead of just setting up and printing. I'll probably think of something else I wanted to ask after I post this but...oh well. Thanks in advance for any replies!
1. Welcome to the board.
2. Though not totally inappropriate, this is far from being "the perfect thread" as it does not address your fluorescent exposure unit, but rather LED.
3. Fortunately for you though, the thread contains links to the Saati step calculator (though not free, as the best rarely is) The industry standard Stoufer version is available here at a good price, but I have no idea what shipping is.http://www.pcbsupplies.com/servlet/the-564/Stouffer-21-Step-Sensitivity/Detail (http://www.pcbsupplies.com/servlet/the-564/Stouffer-21-Step-Sensitivity/Detail)
4, Step Wedge Man also linked you to Murakami's instructions on how to do a manual test (which should be done on each and every emulsion/mech/color variety of screen you have.
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Here are the times Murakami arrived at when testing the Lumitron for T9:
Coated 1:1 sharp EOM 7%
86w 30 seconds 100-thread diameter T White
110w 25 seconds 80- thread diameter T White
150w 22 seconds 48LX - thread diameter S White
150Y 50 seconds 48 - thread diameter S Yellow
225Y 40 seconds 40 - thread diameter S Yellow
330Y 39 seconds 30 - thread diameter S Yellow
If you add the 4 grams of diazo for more water resistance then these times would go up approx 25%
The best test is using your own film. Clear film has a dmax reading, it does block some light, (so does the glass). So a step test is really the best way to find out your exposure time. Shops vary in humidity, drying time, coating technique, and all are unique. So it is not uncommon for 2 shops in the same area to vary in time a little due to variance in coating, film (or CTS), and humidity. If you add diazo, as mentioned, times increase a little since diazo is a slower sensitizer. Coating technique can also create different Emulsion Over Mesh ratios. A 7% EOM will expose faster than a 12% EOM screen of the same mesh count.
Calculators we have found aren't completely accurate on LED units. You are layering 2 pieces of film, which will have a doubled film dmax reading. The film 'shadow' in the emulsion shows that film does block a significant amount of UV energy. A step test on the other hand uses your film and images, so your times will be a bit more accurate.
https://murakamiscreen.com/step-test-to-determine-proper-exposure-times/
pm me if anyone needs more info or trouble shooting of their exposure times.
Alan
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2. Though not totally inappropriate, this is far from being "the perfect thread" as it does not address your fluorescent exposure unit, but rather LED.
My Lumitron is LED, I definitely do not have those flo bulbs.
A couple other techy questions: the coating ratio 1:1, 1:2, or 2:2; is the squeegee side on the left and the substrate side on the right?
I was under the impression this emulsion (Murakami T9) didn't need diazo and it was pre-mixed and ready to go. How and when would I know I need to get it? Is it sold separately? I'm hoping I won't need it but we'll see..
Where does the 7% or 12% EOM come from? So, a 1:1 sharp will be 7% EOM and something like a 1:2 or a 2:2 will be 12% EOM? Would "coverage" suffice as a synonym for EOM?
You are layering 2 pieces of film, which will have a doubled film dmax reading.
I'm pretty sure I'm layering one single film because that's all I'm taping to the screen, unless something here is going over my head lol. And I'm not quite sure what 'dmax' is.
Bare with me fellas. Thank you for the responses! I really appreciate anyone's words of wisdom or correction.
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2. Though not totally inappropriate, this is far from being "the perfect thread" as it does not address your fluorescent exposure unit, but rather LED.
My Lumitron is LED, I definitely do not have those flo bulbs.
:-[
Sorry about that! I had no idea that they kept the same name :o
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OK:
EOM: Emulsion over mesh - This is measured in microns with a thickness gauge. Emulsion thickness minus Mesh thickness = Microns of emulsion more than the mesh thickness. Take this result and divide by emulsion thickness. To make it easy: Mesh = 100 microns Emulsion = 110 microns = `10 more microns of emulsion.
10 divided by 110 = .09 or 9% more emulsion than mesh. This creates durability to resist squeegee abrasion and forms a better ink gasket that controls ink deposit and limits dot gain which will occur if mesh and emulsion are the same thickness and EOM = 0%.
Coating: T9 is thick and can be coated with the sharp edge once on print side followed by once on squeegee side with a firm slow pressure. Go fast = bubbles = pinholes. 1:1 sharp yields about 7%. Scoop coaters have different edge thicknesses, so this is a general advice tip. Two people coating a screen with the same coater may vary by 2-4% depending on speed, angle of coater, and pressure. Generally 1:1 sharp = 5-7% Great for halftones and details. 1:2 sharp = 12% and is better for spot color or discharge.
Diazo - T9 is ready to go right out of the bucket. If you want more water resistance for long runs, adding diazo helps. So do hardeners. If you set up an auto press with 90 duro squeegees and no angle to the squeegee the screen will break down sooner than if you used a 65-70 duro squeegee with 5 degrees more angle and a slightly slower squeegee speed. Art needs can change what you will use for durometer, mesh, and color, just know hard, sharp squeegees at a vertical angle ruin mesh and emulsion by scraping away at the image area. OK for plastisol, but waterbase discharge need a bit of angle, less sharp squeegees, and speed and squeegee pressure controls (which can vary from job to job depending on art). The reason S mesh is so good is you need very little squeegee pressure to transfer ink. This keeps the screen from breaking down as soon as it would with tons of pressure and a vertical angle needed on mesh that does not transfer ink well. If you have to use tons of pressure to print plastisol its time to look at mesh choices.
So diazo adds water resistance, also increases your exposure time a bit. +25% to 50% depending on your unit. Diazo is an additive for T9 to increase resolution and water resistance if needed.
Exposure Calculators - they use 2 pieces of film, a detailed image to expose, and density strips to block the light in ever increasing amounts. You double the estimated time for the exposure calculator test, then there are factor numbers at the bottom. So if T9 exposes at 25 seconds on a 110W on a Lumitron then with a calculator test it would be a 50 second exposure (double the estimated time). If the panel with .5 looks the best, good details, they don't rub off, then .5 times 50 equals 25 saeconds. But the reality is that the calculator uses 2 films. Dmax refers to light blocking ability. Even clear film has some ability to block light, especially ink jet film, image setter not so much. So 2 layers of film in a calculator will block enough light to skew the results since LED has a low wattage. They expose by being closer to the screen. Calculators work better on Metal Halide lamps that are a bit stronger, but LED is faster due to lamps being closer and give decent exposures. thick stencils for gels, puffs and hi density I lean toward Metal Halide.
In any event, I highly recommend a step test. It uses your film, your image, (this is where Dmax is super important, the black image should be in the 3.0 or higher range. A comparison would be sun glasses, dark enough that you could not walk around safely if the black image were sunglasses. You may still see through the black, but wouldn't use it for sun glasses. This saves me from explaining densitometers which is the tool to measure dmax. If your image is really, really transparent you will never be able to expose your screen fully since enough exposure light will get through the image area to lock in the emulsion and make washing the image out impossible.
An imaged screen may have an image, but not be fully exposed. You can underexpose and get an image, but will that be a durable screen? Only full exposure so that there is no slime on the inside of the screen, and no film shadow (a lighter area you can see where the film was when you are washing out.) I have an easy phrase; "Bake the Cake" No baker under cooks his bread or cakes, they would be gooey on the inside. Emulsion is the same. It needs all the quality UV light you give it and still hold the details or it will have many un cross linked molecules inside that creates a weak screen.
Coat a screen once on print side, once on the squeegee side. Dry it well. Make sure you have good black imagery on your film, then do a step test. Each mesh will have its own time.
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That was a super thorough explanation. I really like the t9 especially after getting the trilight 6k. It has the best edge definition of any I’ve used.