Coating screens

[Lizard]

With a large portion of our crew at home I’ve been having to fill in doing art proofing and seps, embroidery digitizing, shipping, answering phones, email, screens, heck you name it. And while doing all these rolls I’ve been implementing and creating new work flows and processes to speed things up.

Well, this morning I had to coat screens and I stumbled upon something that saves so much time. I got everything ready, put the first screen up on the coating rack, grabbed the coaster and realized the screen was facing squeegee side towards me. So I looked at it for a minute and asked...  why can’t I just coat from one side?  What could possibly happen?

We use roller frames so I thought since we do get some drips from the occasional loose corner this might help reduce the amount of emulsion on the bottom side dripping through which is bad for the image. Secondly air between the outer and inner layers of emulsion (it happens if you have staff doing this process) would be eliminated since emulsion would be forced through from side. Well I must say, the screens looked as good or better than any screens I have ever coated. I can’t imagine Haworth much time and money this will save over a year.

Does anyone else coat from one side only?

[brandon]

I assume not all of the "knuckles" or where the mesh meets will be coated completely or at all. But I could be wrong. After several print runs please let us know how it goes.

[Maff]

We coat our S-mesh screens 0/1 , only the squeegee side, 1 slow coat, round side of coater. Our regular mesh screens get 1/1 same settings. When we switched most of our screens to S-mesh awhile ago we started tracking our OEM and were getting way to high OEM when coating both sides, so going 0/1 has worked much better for us. 

Id guess different emulsions could have different results depending on solid counts. We also have the vastex semi auto coater and it helps us control it a bit.

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[Atownsend]

Yep. We coat 1/0 on Saati coater, slowish speed, squeegee wise only. S mesh is a must have for good EOM. Our emulsion usage / cost has dropped about 75% since switching to the auto coater and 1/0 method. 1/1 was just too much EOM, and now I only have two troughs to clean.

[3Deep]

Great thing about screen printing is whatever works in your shop is your standard, unless your the type that like to follow the rule of thumb of the experts so to speak.  Just like we all use different types of lights to burn our screens, different mesh counts, different frames and so on, nothing wrong as long as you are happy with what your getting.

[ZooCity]

Toby, same circumstances here for me, I'm really earning my title of Chief Cook & Bottle Washer these days.   The opportunity to tune up departments and workflow is the silver lining to this.  That said, I'd be more than happy to collect my UI and do my part to flatten the curve by going fishing all day instead but I digress.

We coat everything 1/0 here, from the substrate side.   Thin thread "S" meshes stretched over roller frames here.

Thinner coatings are simply easier to manage throughout the process. 

Credit where it's due- Joe Clarke (RIP brother) knew this but had a hard time convincing textile printers of it, myself included.  Sonny McDonald advocated for a 1/0 coat for years and I also brushed that off.

Turns out, a low EOM screen not only makes a great screen at a far faster rate of coating than other methods but also provides downstream benefits galore.  It solved no less than 2 major bottlenecks and technical issues for us.   Our fancy pants LED exposure system had a problem with excessive heat and expo times from day one and it took care of that.  Reclaim felt slow at the emulsion removal stage, solved.   Even image resolving is almost too fast and far more consistent now.  It improves performance on press in a variety of ways.  I could go on.   

[Frog]

Besides the type of mesh, wouldn't ink type also dictate the ideal EOM?

[brandon]

Interesting thread and reading. Will be following and reviewing in house. Thank you everyone

[ZooCity]

Besides the type of mesh, wouldn't ink type also dictate the ideal EOM?

I thought that for years, maybe a decade or more.  Turns out, not so much! 

It does require adjustments downstream if you are used to printing say, plastisol, through high EOM screens.  They are adjustments for the better though, at least on the autos they are.

[farmboygraphics]

Curious, I coat 1/1 but use the sharp side. I did 1/0 when manual but found my screens breaking down at the edges of the squeegee on the manual so switched 1/1. Do most use the rounded edge only?

[Colin]

Whatever method you use to get between 5%-15% eom is what works.

Personally, I do 1x1 but I back off on the applied angle of the coating trough so it lays down less emulsion (monster max coater).

I always got skittish when thinking of the single coat technique for reasons listed above.

Do What Works!

[Sbrem]

Curious, I coat 1/1 but use the sharp side. I did 1/0 when manual but found my screens breaking down at the edges of the squeegee on the manual so switched 1/1. Do most use the rounded edge only?

I didn't use the round edge as I always thought I had more control with the sharp edge, and would generally coat 2/2. As I started introducing S threads, it became 1/1. I can see using the round edge and coating once on the squeegee side, I would automatically be thinking I need the coat on the print side, most likely due to habit. But for saving time, I can coat more quickly on both sides than I can going very slowly on one side, just another take. In the end, are the prints good, and is the screen standing up?

Steve

[tonypep]

Just don't coat on the bathroom floor and you will do much better!

[Lizard]

I’m never going back to coating two sides. After a couple weeks of coating squeegee side only I can say the screens are as good or better than any screens we have ever made. And the process is faster than flipping the screens around. If we used an auto coated then I could see coating both side but not by hand.

[ZooCity]

Last I looked into auto coaters, I liked the Grunig basic model best and it's a one side coater, which means only one trough to clean and that trough has a nice looking design, very compatible with an imaging workflow with multiple stations.

We hammer our screens with WB/DC/you name it and there's no issue.  Our expo isn't ideal either, we have a starlight which is pretty inferior in terms of UV spectral output to our old metal halide units.  No hardeners (maybe for ultra long runs), no post expo, etc.   The thin thread mesh simply doesn't require a coat on both sides, imo.