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screen printing => Screen Making => Topic started by: Frog on July 05, 2011, 10:00:30 PM
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This just got mentioned in the tape thread.
Have you even heard of it? Do you use it? Which one?
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Well I'm not so sure "permanent" is adviseable but here's the cliff notes for an article I wrote for Printwear about 100 ys ago:
First this method was developed for a company that prints discharge every day on rigid aluminium screens. We stretched our own frames and used painters tape to block out the print area of the screen; leaving app 3/4" of open mesh all around the frame. Screen glue was carefully applied along that open mesh (we used the 2 part cyanoacrilate). Carefully because any dings or imperfections can interfere with the coating procedure. The emulsion overlapped this "perimeter blockout" by 1/2" all around. After imaging the screen was temporarily blocked out using watered down leftover emulsion. Finally rubber tape was used all around the inside perimeter.
So its not for everyone but when perfected it can be a superior and less expensive procedure.
tp
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We have one. It is called Fastener. Cost is $40 per qt. and $78 per gal. I have a couple of customers that are using it. As Tony says you can only use it on static frames.
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I have some here frogger if you want it, it's yours. I didn't care for it.
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I experimented with this very thing not too long ago. I bought some Kiwo Estalan B Lacquer and applied to the screen where our scoop coater would overlap it by about 1/2" on each side. I did 2 screens like this, in about an hour. I'm sure we could knock the times down of application to a reasonable amount if we did it enough, but the entire process was an ass whipping for me and I gave up after 2 screens. It's nice not to have to tape those 2 screens and I'd like to maybe revisit this again in the future if I can find a better or easier product to use.
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And theres the wonderful odor the Estalan B emits. Hope you were well ventilated. The product works however.
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Well, as I said, I started this thread when it popped up in the tape discussion. I'm hoping that Squeegee, the guy who mentioned it, hits us up a little more info.
Yep, pretty much limited to static glued frames, at least from my experience. Back those 100 years of Tony's, I used an expensive, rubbery two part product called Pro-Seal, which I understand was developed as a fuel tank sealant.
Years later, I tried using screen glue, though it was the one part type.
I found that it got brittle, but I seem to remember in a discussion a year or so back, someone said that the present stuff flexes enough to hold up.
Alan, when I was introduced to this stuff, I was printing flat stock, and many of the screens were more than four times the size of our auto screens. Masking tape and a cardboard squeegee, and I don't think that even a six foot screen took a half hour.
What I do do now, is try to tape semi-permanently by taping with my regular rubber adhesive tape inside and out, trying to line up the edges nicely, and only replacing it when it needs it, often many jobs down the line.
I don't use a dip tank right now, so that may be a factor in its success.
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I have some pictures I took of the method we use that I'll put up later but basically it's called liquid tape primecoat sealer, a 2 part system, the sealer and the catalyst though we use very little catalyst, less than recommended. It holds up really well, only rarely do we have to touch up a screen. I have screens that I'd estimate have been reclaimed at least 50-100 times and the blockout is still there and good.
Good application is key, when I get more time I'll put up a better explaination along with pictures.
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So here's the way we apply the liquid tape, first we use a piece of cardboard and a sharpie to outline the border area to be covered, we leave 1/2" of overlap for the scoops. We've used this stuff on EZ frames mostly and some statics.
(http://img96.imageshack.us/img96/940/liquidtape003.jpg)
(http://img215.imageshack.us/img215/6448/liquidtape005.jpg)
We use cheap sponge applicators to apply it, with a headlamp to really see what you're doing. The blockout has to be applied smoothly with no bumps that can interfere with coating. What we do now not in this picture is seal off the edges with blue painter's tape where the panel's locking strip engages the tensioning bar. We do this to keep the blockout from getting into that channel which can make removing the locking strips difficult if it gets in there during application, we then remove the tape after application and before putting the fabric protectors on. We also put a small piece of painters tape on the corners of the mesh to keep the mesh from sticking to the corners during application.
(http://img29.imageshack.us/img29/9643/liquidtape006.jpg)
When we coat, the overlap allows the emulsion to completely seal the screen, so we no longer tape up screens before going to production. We also use an auto coater.
(http://img268.imageshack.us/img268/6141/liquidtape007.jpg)
(http://img810.imageshack.us/img810/2818/liquidtape008.jpg)
It takes practice to get good at this, but my people can do about 6 an hour I'd estimate. I'd say a gallon of this stuff can do about 200 23 x 31 frames. When we started, we did a marathon effort on a Sat and finished all of our frames between 3 people. We have about 150 frames. Just to give an idea of the environment, we do use a dip tank (stencil remover only) and CCI CG4 ink degradent, Liquid Renuit haze remover. We use plastisol, WB and discharge inks. I mention this because I know this blockout will hold up maybe even indefinately to these conditions.
For those interested, it's available at Nazdar, B53504 sealer, C5368OZ catalyst.
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Thats exactly how we did it minus the cardboard.....we used painters tape. Don't rely on some Schlomo to do this. It takes finesse and care but once its done its permanent. Most recommended for those who print waterbase on a daily basis.
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I did ours much the same way squeegee did, but I used a painters brush and it was sloppy, therefore the abnormal amount of time I spent doing it. I wonder if the estalan is as good as the product squeegee uses, Tony? I'd buy something else to do this if it were easier to work with. It's such a damn good idea I want it to work. We spend a lot of time and money on tape.
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The sealer/catalyst squeegee is using sounds similar to a frame adhesive. Works for him so why not try it. Stay away from two part cyanoacrylate frame adhesive thats the stuff that gets brittle. A laquer base frame adhesive should also work.
tp
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It is actually a dual purpose product Tony, a frame adhesive as well. Here's a tech sheet on it. We use like 1/4 the recommended amount of catalyst for our blockout and that keeps it from gelling up.
Alan, definately the sponge applicators work better than brushes, brushes didn't work at all for us. The sponge applicators are cheap tho, we just throw them away after using. I buy them in bulk from McMaster for about $.50 each.
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Squeegee,
That is the way we recommend applying Fastener. It is however a 1 part solution. No need to activate it. Will not come out. In fact when we remesh screens for customers who use it we just mesh over it.
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Sonny,
Send me the MSDS on the Fastner.
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What about "locking" some emulsion on the screen in that area? I know that's taboo in normal situations but could these be a lower priced, readily available alternative or would it be more expensive?
I will be doing this VERY soon to my screens as I have no desire to mess with tape. :)
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Though there are some hardeners that make emulsions permanent, I am not at all sure if they will seal the inside of the screen where the mesh hits the frame.
You could perhaps look into RTV silicone for that part of the equation though. Good for squeegees too!
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The RTV caused more problems than it was worth for me. It would start to come off and get int ink. Really annoying. Depends on your ink clean/reclaim chemistry though.
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I don't know how I missed this thread- it's awesome. I wish all our screens looked like squeegee's. Not only time and waste saving but what a nice clean flow for the screens not having to pull that tape off and put it back on every time. I can see this being a major benefit for wb jobs and will definitely be trying out the liquid tape on our big diamond chase screens for the flatstock presses.
For years now I've tried to find some way to achieve this with roller frames but it just ain't happening. Now that I'm all into the low tension, thin thread mesh, roller frames seem like much less of a necessity. I'll have to think about that for the future, I'd probably rather have blocked out screens like this than the control of a roller frame.
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Get yourself a larger coater. Problem solved. We dont block out or tape edges anymore.