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screen printing => General Screen Printing => Topic started by: Shanarchy on December 01, 2013, 12:26:44 PM
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From time to time I still have trouble with underbases. Printing manually, I lay down a pretty white/smooth first print. Sometimes I have a lot of trouble getting the top color to sit nice on it. Where you can still see tons of white dots, or the color isn't consistent (high and low shades). If I p-f-p the top color, the color is solid, but the print becomes too thick and shiny. Can the ink I'm using for the top color make a big difference? Last week I printed pink over a white underbase and it looked perfect. It was a Miami Ink HO color. It wasn't a super opaque that you could p-f-p without an underbase, but more so had better opacity. The ink I'm using now is a WM Plastics royal blue type shade. I'm not sure what it is (special mix), but I'm guessing it is an AP ink.
Are AP inks not ideal for printing over an underbase? Am I missing something obvious here?
Thoughts? Suggestions?
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This is a heat issue. The first example of white dots is too much heat. The second is not enough heat. A "flashed" ink should feel like paper not sticky. Also look at stroke speed and pressure. Ink pushed into the garment competes with said garment for heat in flashing and curing. The object is to lay the ink "on" top of the garment. This is done with proper mesh, squeegee, and ink selection among other parameters like press level, off contact, etc.
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Sonny, do you think I'm over flashing my underbase? I don't think it's under flashed. I can touch the ink with my finger and it won't come up.
I should add that I'm printing these on a manual.
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Off contact of your top colours is a big factor in how they go down too. Printing on a flashed base should be easy-peasy and clear in one stroke nicely, even on higher mesh counts.
Flash just enough so the base isn't tacky. Overflashing can cause fish-eye in the top colors during the trip through the oven.
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Sonny, do you think I'm over flashing my underbase? I don't think it's under flashed. I can touch the ink with my finger and it won't come up.
I should add that I'm printing these on a manual.
If it is tacky or sticky to the touch, then yes.
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Sonny, do you think I'm over flashing my underbase? I don't think it's under flashed. I can touch the ink with my finger and it won't come up.
I should add that I'm printing these on a manual.
If it is tacky or sticky to the touch, then yes.
I'm going to disagree with Sonny on this one and I don't have much time to go into what I think the issue is right now but when I get a chance to sit down and type it out I will come back to this. I don't see those characteristics, especially the UB poking through the top color, being caused by excessive flashing, just my opinion. Other things cause those problems here at our shop, starting at the foundation/underbase. Any imperfections in your underbase will be seen with your top colors.
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It is because you are printing. Again you should not be worrying about that
Sam
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I imagine it like this. The base is on a pretty low mesh and your underbase white ink is thick. Add to that, the top blue ink (sounds thin). This could make your white halftones protrude thru the blue. With big dots on underbase and low mesh(causing a raised edge) and a over flashed base, cause it to really show even thinner since only a very thin layer of blue ink sits on top...and your blue ink falls to the shirt color on the outside of those dots. This makes the white dots seem to stand out even more. Your squeegee is scraping the blue ink coverage off of the mostly cured white dots.
Remember that a white underbase is only intended to be intense enough to help that blue maintain is true hue. If the blue overprints everything...you do not need a bright white lay down. For example, sometimes I use a 305 mesh as a white underbase with no halftone. Less ink, fast flash.
That's how I see it in me Lil head.
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I underbase with a 110. I print stroke followed by a dry stroke to make sure the print is flat and smooth. Then I flash. Top coat through a 160.
I know my mesh counts are on the low side, but I honestly do no know how people are (manually) printing white ink through high mesh counts and clearing the screen without killing their bodies.
The area in question is pretty much a solid 7"x 7" square. I'm sure that is not helping.
The underbase is not halftoned, but the topcoat has tons of white speckles still showing through the ink.
I tested and made sure the underbase was just brought to a proper flash. Not over flashed, and not anything being picked up on your fingers. I waited 2 minutes to make sure that pallet was nice and cool. Still having the same issue.
Obviously it must be something I'm doing, but not sure exactly what.
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Post up a pic of the art. Do you have higher mesh? What are the tensions like?
Your troubles printing on a manual are connected with your mesh, the inks and squeegee blade type.
Thick inks and low mesh make for clearing g the screen well.
Thin inks and high mesh make for clearing the mesh easier but you do need tight screens and the right inks. Hard squeegees help cut the ink. Softer squeegees wi sort of "mash" the inks thru to put it in basic terms
Higher tension, higher mesh, low off contact, thiner inks (inks designed fir high mesh) and sharp hard duro squeegees (like a 70, 70/90/70 an 80 or even a 90 with an almost verical angle to start...make for good manual printing ( for my recipe). I don't print in house yet, but that's what I suggest to many and they end up with great prints.
I know I'm reaching outside my bounds since I don't print yet myself, but for what it's worth, it works for others I've suggested to.
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I'd hedge to bet the 110 may seem smooth, but either of these can be happening:
-Any blowing agent (puff) in the white? The knuckles of a coarse 110 are making peaks,
with or without raising of UB.
-Not enough pressure on the blue. I've seen specks showing if not enough pressure,
or hit it twice without flashing, just to cover smooth.
Try a 125 or 156 to let the UB be smoother.
It will still print easy on a manual.
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I always use a 156 to 160 for underbase.
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Dan,
I just checked the tension of the screens in question. The underbase is at 20 and the top ink is at 24. Both way lower than I'd like to admit. Looks like it may be a good time to go trough all of my screens and retension them real soon.
Squeegees are triple duro 70/90/70.
I'll get you a pic of the artwork in a bit.
Gary,
I'm using Miami Superior white. I don't know if there is a blowing agent in there, but it's not very noticeable if there is.
I don't think there is a pressure issue with the blue. The ink is clearing the screen. But I can always try to give it more pressure to see if it makes a difference.
I may get some 125 mesh to try with white and see how that differs from the 110. I also need to try underbasing with gray at some point.
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I always use a 156 to 160 for underbase.
Wayne,
You print manually, do you find it a struggle getting the white through a 160?
Something I've wondered recently is the rubber top Vastex pallets. It seems to be a different type of rubber than other pallets use. It seems softer (could be my imagination). Could my printing surface be softer than other presses (hard wood, standard rubber coated aluminum pallets)?
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Shane, I am old and weak and print manually (push stroke on full size) and have almost eliminated 110's (at least for regular opaques)
I do not use retensionables.
I did switch to almost all 160's, and most cotton or low bleed inks print pretty well. These are not your father's inks nowadays.
That said, I did recently get some frames re-meshed with 140 and 125 for when I need a little more ooomph.
(a fleece only job will probably see the 125's)
Now, if you are having trouble with your white through a 160, you may want to put the whack on it (in it)
It will be smoother, easier to clear, and as an underbase, a slight reduction in opacity probably won't matter
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I hate the idea of adding a reducer to my inks. Ideally, I'd rather find an ink that just needs a good stir. What are you using for your white? And are you adding anything to it? Also, what squeegee duro are you using?
I've tried a handful and find it hard to believe there is going to be something dramatically easier to work with than the Miami (which isn't dramatically different than others).
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I always use a 156 to 160 for underbase.
Wayne,
You print manually, do you find it a struggle getting the white through a 160?
Something I've wondered recently is the rubber top Vastex pallets. It seems to be a different type of rubber than other pallets use. It seems softer (could be my imagination). Could my printing surface be softer than other presses (hard wood, standard rubber coated aluminum pallets)?
I'm manual and have the typical melamine pallets. I use QCM Glacier White which is pretty creamy and no, don't really have a problem clearing the ink. I'm also using a triple durometer (90/70/90) flood and then push stroke. My off-contact is 1/8 inch and I have retensionables at about 27-30 newtons.
That's an interesting thought on the rubber top pallets on a manual. Don't know the answer, but I would think since plastisol is supposed to lay for the most part on top of the shirt, I'd be surprised if the rubber topped pallets are an issue.
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I hate the idea of adding a reducer to my inks. Ideally, I'd rather find an ink that just needs a good stir. What are you using for your white? And are you adding anything to it? Also, what squeegee duro are you using?
I've tried a handful and find it hard to believe there is going to be something dramatically easier to work with than the Miami (which isn't dramatically different than others).
First off, before whites were as friendly as they are now, a Union tech addressed the issue of "Won't reducers or bases affect the opacity of my whites?" with this bit of advice," Not if that's what it takes to clear the screen."
As it is, I only find myself adding base or reducer to the occasional "climbers"
My old IC low viscosity, and then eventually Zenon, Wilflex Artist, and my present Streetfighters all clear a 160 just fine.
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What really helped us a lot was changing from a 128N RollerMesh for example to a 150S Murakami Mesh. We get a much better base white with a higher mesh count that costs the fraction of the Roller Mesh. Of course I don`t doubt at all that you can get as well a good base white with the Roller Mesh but overall our print quality has improved using Smartmesh.
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or Shane you can start listening to me and start making money vs. worrying about screen tension, mesh count and what it looks like!
hahahahah
enjoy Monday!
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or Shane you can start listening to me and start making money vs. worrying about screen tension, mesh count and what it looks like!
hahahahah
enjoy Monday!
You talked me into it Sam. I'm closing the business immediately.
Seriously though. I do this because I truly enjoy it.
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What really helped us a lot was changing from a 128N RollerMesh for example to a 150S Murakami Mesh. We get a much better base white with a higher mesh count that costs the fraction of the Roller Mesh. Of course I don`t doubt at all that you can get as well a good base white with the Roller Mesh but overall our print quality has improved using Smartmesh.
I was thinking about switching my screens to Smartmesh. I heard that I would want to bounce up to higher mesh counts because the higher mesh counts will give you more open area due to thinner threads. I have a sample at the shop I need to test out so I can figure which mesh counts I should get. I'm also trying to determine if I want to go blot or panel. I love the panels, but to do a lot of screens at once I think it may get too expensive.
Do you use bolt or sur-loc's?
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First off, before whites were as friendly as they are now, a Union tech addressed the issue of "Won't reducers or bases affect the opacity of my whites?" with this bit of advice," Not if that's what it takes to clear the screen."
As it is, I only find myself adding base or reducer to the occasional "climbers"
My old IC low viscosity, and then eventually Zenon, Wilflex Artist, and my present Streetfighters all clear a 160 just fine.
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I get what you are saying, and it is completely true. But, if other people are clearing their white through a 160, then I should be able to as well. I think I have a different underlying problem I need to figure out before hitting the reducer.
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We use S mesh and will never go back. 150 is what we use for UB or spot colors, often going to 180's. get the chart, it will show you all the data you need right along side of their T mesh.
We have also fallen out of love with Miami smooth (we print manual as well.) We got some samples of arctic white by Excalibur and have a new mistress in the shop.
We also had a UB speckle issue with a blue top coat. This was on 100% poly with Rutland poly white and it was due to the blowing agent (we assume).
Good luck man.
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Ok, I've finally got a chance to give my take on this. I've been printing sample prints on the manual the last month, testing all kinds of inks, mesh, substrates using a six color job so I've seen the things you're talking about. I've also seen these things on the auto when I was printing but much less often than on the manual. The peaks and valleys in the underbase are likely the cause of your spots and they are showing up due to the top color not filling in the valleys or the peaks are poking up through a thin layer of top color. There are several things you can do but the best long term solution would be to move to thin thread mesh. We still use lower mesh counts with the thin thread mesh unlike most. Printing with a 123/55 will put a little more ink down than a 156/64 (not noticeable) but with so much less effort and faster print stroke. That will make your UB much smoother since it's on top of the shirt and has virtually no peaks or valleys in the ink deposit.
Let's use the 156/64 sefar and 150/48 murakami as an example. The 150/48 will deposit a very similar amount of ink as the 156/64, but the percentage open area of the 150 is about 20% more than the 156/64. You'll need very little pressure to clear a thick white ink from the 150. The 150/48 also is about 40 microns thinner overall giving you a much flatter ink surface to print on top of.
Completely changing out your mesh counts doesn't really help you short term so you'll have to do something in the meantime to get you through. I'd suggest moving to a higher mesh count for your underbase so you'll get a slightly smoother surface to print on, but you'll lose opacity by doing so. Since you're manually printing, double stroking a 156/64 won't be that big of a deal and you'll probably get rid of the white specs showing through your top colors with a smoother UB. You can lower your top color mesh count to gain some opacity and that will for sure get rid of the UB showing through cause your top color will really fill in any inconsistencies in your UB if it deposits a thicker layer of ink. If you don't matte down the fibers with the higher mesh count then you'll have issues just like you did before so I can't guarantee you won't be trading in one problem for another. You might have to adjust your ink like Frog said to clear the ink with less pressure.
We normally don't use higher mesh counts for UB because of the higher print pressure needed and the ink going into the shirt. It creates more problems if you can't get the ink to clear a 156/64 with two light strokes. If you can clear the UB through the 156/64 without driving the ink into the shirt you'll solve some of your issues until you get your hands on some thin thread mesh.
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small suggestion. after we print bases - or even stand alone white for that matter, we use a teflon/smoother screen..it will knock down those peaks/valleys Al is speaking of. we use it on almost every job we run. expose a blank screen, tape a teflon sheet to the bottom, toss some ink in it for a "lube" and print it right after your flash.
we found this material works very well.
http://www.stahls.com/heat-press-cover-sheet (http://www.stahls.com/heat-press-cover-sheet)
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i use wilflex epic sprint white.....156 mesh....60 or 70 durometer (yellow blade)
I have to pull 2 to 3 times to clean the screen
I'm going to see if there is a 156 S-mesh....i think that will require 1 to 2 pulls to clean the screen...the next screes I buy for underbasing will be 156 S-Meshes.
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i use wilflex epic sprint white.....156 mesh....60 or 70 durometer (yellow blade)
I have to pull 2 to 3 times to clean the screen
I'm going to see if there is a 156 S-mesh....i think that will require 1 to 2 pulls to clean the screen...the next screes I buy for underbasing will be 156 S-Meshes.
CHeck mesh tension. Use tight screens and harder squeegee. You get closer off contact with tighter screens. Try using a harder squeegee like an 80 or 90. Keep angle more vertical.
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small suggestion. after we print bases - or even stand alone white for that matter, we use a teflon/smoother screen..it will knock down those peaks/valleys Al is speaking of. we use it on almost every job we run. expose a blank screen, tape a teflon sheet to the bottom, toss some ink in it for a "lube" and print it right after your flash.
we found this material works very well.
[url]http://www.stahls.com/heat-press-cover-sheet[/url] ([url]http://www.stahls.com/heat-press-cover-sheet[/url])
I'm manually printing right now, but auto shopping. I was thinking of investing in the action roller screen thing to use as a smoothing station after the flash. This may really help to confirm me doing this. Seems like a great step to throw in that really won't change production time.
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I had problems like this for a while until did all the following together for my whites:
2/2 coating round side, drying squeegee side up
using a 70/90/70 squeegee
High angled, slow flood (just fill the stencil, no bulging out of it, which will cause blur
Quick, lower angled pull (or more recently push) stroke
triangle poly excel white (this stuff is expensive, but far and away the best white I've printed manually. I even use it on 100% cotton because it just blows everything else out of the water)
I no longer have to do a clearing stroke, and a p/f/p with a 110 or 160 static with normal mesh is literally 100% opaque with no fibration and perfectly smooth finish. The 160 requires a bit more pressure though. A lot of shops would probably let the first stroke out the door, but I won't. I do all the same as above with 160 or even 230 for strictly underbasing and just one shot it, but I prefer to simply p/f/p instead of doing a highlight white screen and print the colors on top of the thick deposit for most jobs.