Screen exposing/wash out problems HELP!

[Shanarchy]

I agree with Colin. The variable that seems most likely is the thin thread.

One thing that jumped out to me was that you said you no longer rinse the inside of the screen bc of this problem.
To me this sounds like classic under exposure.

So a few quick thoughts.

Was the old mesh yellow too? If not maybe try adding some time to exposure.

Is the cap film maybe to thick? If so adding some time should help.
*-we're not using cap film, but we had to make changes to our coating techniques bc of EOM thickness on thin thread.

Murphy

At this point under exposure may be the only thing I feel confident in ruling out. I did a recent re/test with an exposure calculator which says I should be at 55 LTU. For years I exposed at 60ltu with. I issues. I've even brought the exposure time up to 105. (Yellow mesh was being exposed higher but also dialed in the same way).

I don't think it's improper drying. I'm a small shop so my screens are usually allowed at least 24 hours to dry. With cap film you can also tell when you pull the poly backer off of the screen isn't dry enough.

I'm about to coat a few screens. I am going to try a couple with the magic mesh prep (water retainer) and a couple without. I will make sure the screens are thoroughly sprayed with water on the inside to make sure I'm getting maximum capillary action while also pushing harder with the squeegee on the back side of the screen to ensure maximum pressure to push the film in.

I'm going to order a couple of statics today (regular mesh and s mesh) as this may be the best way to determine exactly which new variable is causing the issue (new mesh, thin thread mesh, frame style). Unfortunately I'll have to wait a few days before I can do that testing.

[whitewater]

-EZ frame frame issue. The channels trap dip tank solution which mix with the water during screen wash out and then come into contact with the cap film during wash out causing the film to bubble (or whatever you want to call it). That said I have been spending a lot of extra time trying to make sure the screens are properly rinsed. But I may be leaning towards this.

if you think it may be this, why not let the screen dry throughly, do not apply the film right away, let it totally air dry, then rewet it and apply. Maybe during the reclaim process with the newer presssure washer, maybe the its hitting back of washout booth and spraying back on itself from the wall behind. Just a thought..

[Shanarchy]

I would try a new degreaser.

I stopped using a degreaser years ago and never saw an issue. That said I've recently have tried Franmar degreaser, ulanogel (abraded and degreaser), ulano Magic mesh prep (water retainer and degreaser), and Saati direct prep 3 (degreaser and water retainer).  Not sure if any of them are helping, but none of them have solved the problem.

[Shanarchy]

-EZ frame frame issue. The channels trap dip tank solution which mix with the water during screen wash out and then come into contact with the cap film during wash out causing the film to bubble (or whatever you want to call it). That said I have been spending a lot of extra time trying to make sure the screens are properly rinsed. But I may be leaning towards this.

if you think it may be this, why not let the screen dry throughly, do not apply the film right away, let it totally air dry, then rewet it and apply. Maybe during the reclaim process with the newer presssure washer, maybe the its hitting back of washout booth and spraying back on itself from the wall behind. Just a thought..

The screens I'm going to do today were cleaned Sunday and will be coated with film today. If I see better results than you may be into something.

[mimosatexas]

I soft rinse and flood rinse after pressure washing specifically because if I don't i occasionally end up with little snake eyes from contamination from chemicals that aren't fully washed out the mesh.  Not every screen, and not even bad enough to matter 95% of the time if I were to skip it, but I prefer to do things right instead of end up with an issue out of the blue.  Might try that.

Out of curiosity, what is the reason you use the cap film instead of standard emulsion anyway?  Doesn't it cost a lot more?

[3Deep]

Speaking of thin thread screen's they don't have as much knuckle as regular mesh to hold the emulsion or cap film.

[Shanarchy]

Out of curiosity, what is the reason you use the cap film instead of standard emulsion anyway?  Doesn't it cost a lot more?

I pay $2.10/screen (23x31's).

If I remember correctly, I think emulsion was between $.50-$1/screen depending the brand, etc.

I justify the extra $1/screen with time savings I get for being able to quickly coat immediately after reclaim.

Plus I feel film offers better edge definition, and guarantees you the exact same coating on every screen so one less variable to control, exposure time will always be identical, etc.

I'm just hoping this does not come down to a compatibility issue between thin thread mesh and capillary film. 

[Shanarchy]

Have you started or stopped using a water softener, or perhaps been using a softener and allowed it to run out of salt.  Looking for changes that may have occurred which you have not linked to the issue yet.  Think soapy water in a shower and how the softness of the water affects bubbles, this is a surface tension issue.

Capillary film is dependent on water being held in the mesh via surface tension of the water, the thing which allows bugs to walk on water, and if that surface tension is inadequate your mesh will not hold the water to allow the capillary action to be effective.

On that same theory the thin thread will increase the theoretical open area of the mesh and the surface tension may not allow the cells to hold water for proper capillary adhesion.

Applying cap film to 60 mesh is a problem for the same reason but is much easier to understand when you can see huge holes in the mesh.

GREAT CONVERSATION

The water situation has not changed as far as I know. Old mill building, no water softeners, cold water only, etc. The only real change there would be the power washer.

I just ordered a static with S mesh 150 and another with normal mesh 110. They will be here on Friday. I'm looking to see if I have the problem only occurs on the S mesh/thin thread screen.

[ebscreen]

Along the lines of what Mr Kitson mentioned, we've had oddball issues crop up
when the local water company started adding an algaecide or somesuch during the summer last
year. Probably not your issue but just wanted to mention it in case, some things are out of our control.
I'd reckon a charcoal filter would go a long way for us.

Hat's off to you for being able to use cap film in the first place however. That stuff always
made me want to throw things, no matter how I tried to adhere it.

[Sbrem]

When you rinse, after reclaiming, does the water cascade down the mesh cleanly? Or does it seem to "avoid" certain areas? If it's "avoiding" then the mesh isn't clean, if the mesh is clean, then the water cascades very smoothly. Perhaps some haze remover in that area... it is strange.

Steve

[Shanarchy]

*update*

I exposed two screens today. Both washed out without the issue. I'm not expecting the problem to be solved as I have had screens wash out ok every now and then. But, I only coated a few so I could have a little bit of a better idea of exactly what was done on these in hopes of replicating as I go.

-These two screens were cleaned in the dip tank Sunday night and set to dry.
-Pressure washed this morning. The rinsed with a separate hose with a light spray nozzle on it that I use for screen wash out.
-These were not degreased or had a mesh prep/wetting agent used on them (this is recommended by the film manufacturer but a step I found I did not need to do and stopped years ago).
-I thought for the first time about ENCAPSULATION. I sprayed the inside of the screen with a water bottle a LOT heavier than I usually do. I then used a couple of hard squeegee stroked to really force the film into the screen.
-screens were set to dry for appx 12 hours
-light dusting of powder, then film (same film I've been using the past several failed screens) taped to back
-I increased my exposure time. But I do not feel this issue was underexposure. I had this problem happening to me for a long time using an even higher exposure time than I did today.

Both screens (white 150 mesh and yellow 180 mesh) washed out without showing any signs of the issue I've been having. Both screens (particularly the yellow mesh) was tough to wash out. The screens were definitely overexposed. I do not think the feel of overexposure could be weak films. But I will still explore that option as well.

Going forward (or at least for now), I plan to continue to eliminate degreasing (except new mesh) and using a wetting agent. I did not use them before, and seem like I do not need to do them now. 

I will not yet lower my exposure times. Although I know they are too high. It did work for these screens, and I do not want to change multiple variables at the same time. If I can put together a streak of exposing screens without issue I will slowly work the exposure time down until I either reach the time determined by my exposure calculator or I notice an issue with wash out.

At this moment I am leaning towards improper encapsulation. Possibly caused my thin thread and more open area vs what I used for years. In my mind this makes sense because I can not see how this issue is not being directly related to the use of thin thread mesh. Otherwise how could I never have had this problem before? Keep your fingers crossed for me on this one!

The secondary change would be letting the screens dry after cleaning. But I am not quite sure how this would be any different than coating the screens and some sitting for up to a week before being exposed. IF (big if) I can get a few more screens working with zero issue, this will be the first thing I change to see if the issue immediately pops back up.

Please keep any and all feedback coming. This has been a long road for me. I'll continue to update with my results.

Thank you to all who are trying to help me through this.

[Maff]

Maybe there is a better Cap film specifically for thin thread mesh?

Maybe a thinner Cap film?

We coat directly, but we had a lot of trouble when we first switched to thin thread. It seemed that our emulsion wasn't adhering thoroughly and our images were not exposing well.  We tried a lot of the same ideas you had and nothing changed it off us either.

But after we starting to track our EOM we realized we were coating way to thick and once we got our EOM down we saw much better results.
We also saw notable improvements when we were drying our screens and our humidity was lower than 25% and the temp over 70.

[Underbase37]

I agree with Maff.

Our EOM was thick when first switching to thin mesh.

*not using cap film here, direct deposit. But can't help thinking there's somthing going on in the same way.

Murphy

[ScreenFoo]

-I thought for the first time about ENCAPSULATION. I sprayed the inside of the screen with a water bottle a LOT heavier than I usually do. I then used a couple of hard squeegee stroked to really force the film into the screen.

I actually just popped in to this thread to mention this.  I think you got it right there. 

Thinking about the difference between my 150/48 and a 156/64, you'd have 30%+ more surface area on the thicker threads.
It's certainly not going to be more forgiving with less area for the film to adhere to.

[fishman008]

I was given a sample of Ulano Orange 50 I believe. Had 5 sheets of cap film in it. I applied 2 sheets on brand new 150S thread mesh, and 2 sheets on shut-loc panel frame 158 mesh, econ panel they call it. Both yellow mesh, both degreased and then ulano magic mesh prep. And I got better results applying to the e-con panel, which are thicker thread. For some reason ulano Orange 50 does not adhere well to thin thread S mesh. I got similar results as you did. But, I reclaimed and applied direct emulsion the S mesh, exposed perfect. I recall someone had same problems. Maybe Cap film or at least ulano orange 50 don't agree with thin thread mesh. But there is a Ulano Orange 30 for mesh counts over 200 cap film. That might be the answer to thin thread 150S mesh. But I ordered from tech support the 50, its super convenient and works great on thicker thread mesh. Great for large spot color work. But I sure wish it would adhere to the S mesh because that mesh is amazing, as everyone has stated here. Maybe Al from the mesh manufacture can spread some wisdom on this subject.