Emulsion To Mesh Adhesion Issue???

[LacedUp73]

First of all, this is the first time I've EVER posted ANYTHING, on one of these forums, so please bare with me, huh???

I had commented about a problem I'm having with my screens, on one of your YouTube videos, and was told to post it here on your forum. So, without further delay:

OK, the issue I'm having is I keep getting these splotchy spots of emulsion, after I spray the screen down. It looks as if the emulsion is peeling off the screen. As a matter of fact, I WAS actually ABLE to peel the emulsion off, one time!?!?!? Stencil and all!?!?!? Once I let the screen dry, those splotchy spots crust up on the screen, which makes reclaiming the screen very difficult. What am I doing wrong??? How can I keep this from happening, in the future??? Luckily, the images I've been printing, haven't required using the entire screen, as it wouldn't work out all that well, with these splotches popping up along the sides of the screen. Oh, that's another thing, it seems to only happen on the SIDES of the screens. Any help I could get, would GREATLY be appreciated. Thanks, so very much, for your time. Cheers \m/

[Shamax]

I could hazard some guesses, but first, a little more info would be helpful:

What emulsion are you using? (Reminds me of the Ryonet WBP that comes with the starter kit)
How are you coating the screen? One pass on each side (substrate side, then ink side), and are you using the sharper edge of the scoop coater, or the more rounded edge?
How are you storing and drying the screens (horizontally, I hope)?
What's your light source for exposure?
And how are you doing your post-exposure washout, and for how long do you typical need to wash?

There's a lot of little factors that could contribute to it, but it looks like excess (possibly uneven) emulsion that's not totally exposing and not totally washing out either. When you sees these spots develop, are you able to continue washing them completely, or rub them lightly to speed it along?

[Catspit Productions]

Andy is right; more detail will help but let me suggest a few basic things. First make sure to prep the screens well. If they are new screens you need to abrade the mesh some so the emulsion has something to bite onto. Use an abrader made for mesh prepping screens for screen printing. You can use other b=abraders but they may be too rough on the polyester mesh. Make sure to thoroughly degrease the mesh as well. Rinse thoroughly and let dry in a clean area where no debris may get back onto it.







Once it’s dry coat the screen with room temperature emulsion 1/1. Do one pass on the substrate side and one final pass on the inkwell side. Put the screen in a place where it can dry in the pitch black while sitting with the substrate side facing and parallel to the ground. A humidifier in this room can help with drying but use it only if you are experiencing humidity well above 50%. Emulsion is over 50% water so you want the drying area to be able to “absorb” the water easily and not dwell in the emulsion.



Now, once it’s dry and you do you exposure this is critical. You ideally should be able to washout a screen in 5 minutes or less. The more time you spend in the water washing out the more likely the cured or semi cured emulsion can get saturated with water and begin to separate from the mesh.

The wrinkling you see there looks like a combination of poor mesh adhesion and too much time in the washout booth. If you are finding that you need more than 5 minutes or so you may want to switch to a better emulsion or perhaps use more dense film positives.

But if you fill in some info as Andy suggests we could perhaps help more. I would ask in addition:

What are you using for film positives?
How are you coating the screens with emulsion as far as passes as well as scoop coater used?
Are you getting a nice even looking coat of emulsion when dry?
Is this new mesh and how do you prep the mesh for coating with emulsion?

Thanks for posting; I appreciate the support in doing so. I t helps us help everyone and build resources on the forum. Thank you!

[Catspit Productions]

This article may help too:

http://www.catspitproductionsllc.com/me ... ation.html

I'm thinking of doing a quick tips video on this for tomorrow. A few people seem to possibly have the same issue so maybe it needs some attention

[LacedUp73]

I could hazard some guesses, but first, a little more info would be helpful:

What emulsion are you using? (Reminds me of the Ryonet WBP that comes with the starter kit)
How are you coating the screen? One pass on each side (substrate side, then ink side), and are you using the sharper edge of the scoop coater, or the more rounded edge?
How are you storing and drying the screens (horizontally, I hope)?
What's your light source for exposure?
And how are you doing your post-exposure washout, and for how long do you typical need to wash?

There's a lot of little factors that could contribute to it, but it looks like excess (possibly uneven) emulsion that's not totally exposing and not totally washing out either. When you sees these spots develop, are you able to continue washing them completely, or rub them lightly to speed it along?

OK, again, bare with me, for I know not what the heck I'm doing, when it comes to these forums!?!?!?

First of all, thanks, so much, Andy, for taking the time out to help me out with this issue, that's been costing me money, and a lot of time. I just looked on your website briefly, and saw that you had done some printing for Njiqahdda, huh??? Very cool band. I own a few things by them. Anyways, on to the matter at hand. I'm using Ryonet's ProChem DXP Pink Emulsion, and yes, it did come with one of their kits (I bought the 4-color, 2-station silver press, with all the trimmings.) When I coat the screen, I usually just give each side one run over with the emulsion, and then I run the screen coater over again, but without the emulsion touching the screen, as just a means of scraping/spreading the emulsion out evenly, on each side. And, I really couldn't tell you which side of the coater I've been using, as I wasn't aware that there was a difference??? Pardon my ignorance, on such matters, but I still have a LOT to learn. Now, when I store my screens, I do store them horizontally, with the substrate side facing down. I've started employing the use of a small oscillating fan, to speed the drying process up, a bit. Now, I should also add that when I first started inquiring others about this issue, I was told that I was probably getting these splotches, because I'm preparing my screens in a room that is heavy with humidity. But, upon further inspection, I found out that my dark room, typically keeps a 40% humidity level, naturally, so I'm thinking that high humidity is NOT the cause, after all??? Now, as for my light source, I'm using Ryonet's 20x24 Aluminum UV Screen Exposure Unit, which holds 8 - 15 watt unfiltered UV black lights. I've been going with 3 minutes, and 45 seconds, for exposure time, on 110 - 156 white mesh screens. Now, when it comes to the washout, I used to use a high powered nozzle, but was told by another very successful screen printer, that I don't want to use such a high powered stream, for this (does that sound right to you???) So, now I've just been using whatever pressure that's been coming out of my water hose, with no attachments, at all. Sometimes I use the ol' thumb over the end of the hose technique, but now that I type it, it doesn't sound all that effective!?!?!? HAHAHA!!! Anyways, I'm thinking that's not my problem, solely, but hopefully, with the info. I've provided you with, you'll be able to shed a little more light on the situation, for me??? In any case, again, I thank you, for taking the time out of your busy schedule, to help me out. I REALLY appreciate it!!! If there's any more info. you need, feel free to ask. Cheers \m/

[LacedUp73]

[quote="Catspit Productions"]Andy is right; more detail will help but let me suggest a few basic things. First make sure to prep the screens well. If they are new screens you need to abrade the mesh some so the emulsion has something to bite onto. Use an abrader made for mesh prepping screens for screen printing. You can use other b=abraders but they may be too rough on the polyester mesh. Make sure to thoroughly degrease the mesh as well. Rinse thoroughly and let dry in a clean area where no debris may get back onto it.

(VIDEOS)

Once it’s dry coat the screen with room temperature emulsion 1/1. Do one pass on the substrate side and one final pass on the inkwell side. Put the screen in a place where it can dry in the pitch black while sitting with the substrate side facing and parallel to the ground. A humidifier in this room can help with drying but use it only if you are experiencing humidity well above 50%. Emulsion is over 50% water so you want the drying area to be able to “absorb” the water easily and not dwell in the emulsion.

(VIDEOS)

Now, once it’s dry and you do you exposure this is critical. You ideally should be able to washout a screen in 5 minutes or less. The more time you spend in the water washing out the more likely the cured or semi cured emulsion can get saturated with water and begin to separate from the mesh.

The wrinkling you see there looks like a combination of poor mesh adhesion and too much time in the washout booth. If you are finding that you need more than 5 minutes or so you may want to switch to a better emulsion or perhaps use more dense film positives.

But if you fill in some info as Andy suggests we could perhaps help more. I would ask in addition:

What are you using for film positives?
How are you coating the screens with emulsion as far as passes as well as scoop coater used?
Are you getting a nice even looking coat of emulsion when dry?
Is this new mesh and how do you prep the mesh for coating with emulsion?

Thanks for posting; I appreciate the support in doing so. I t helps us help everyone and build resources on the forum. Thank you! [/quote


OK, I'm going to ATTEMPT to answer your questions, but, first, I really have to thank you for the plethora of invaluable info. you've made available to the screen printing community. I really enjoy the videos, as they're EXTREMELY helpful to laymen, like myself, and seasoned vet's, alike. Countless thanks. Now, onto the nitty AND the gritty. I'm not exactly sure what kind of film I'm using, as far as manufacturer and model # goes??? I can tell you that it came along with the particular kit that I bought from Ryonet, including a reorder form with the name "R-FILM" big and bold at the top, if that's of any help??? Again, as I said to Andy, you have to pardon my ignorance in such matters, as I'm totally just starting out, on my own, with a LOT yet to learn. Now, I typically use a 1 and 1 coating, but also do a follow up run on each side of the screen, without letting the emulsion touch, as a way to rid both sides of any possible excess emulsion. The coater I have is made by Ryonet, which I really don't care for, as the end caps are not only removable, but are wont to fall off, of their own accord!?!?!? Not only that, but the emulsion runs through the cracks quite easily, creating those "RUNNIES" you mentioned in your videos. When I do encounter those infernal "RUNNIES", I simply take a little ink scooper card, and spread it out towards the edges of the screen. Now, keep in mind, that's where I tend to experience those splotches, towards the edges of the screen/mesh. I believe the coater used in your videos is different from the one that I have, and I'm going to look into getting one similar. OK, now, when all's said and done, and the emulsion is freshly coated on the screen, it would definitely appear that I have a nice and even, pretty coat of emulsion. That's to say that nothing stands out, anyways. But, once it starts to dry, a bit, I can start to see certain parts have turned a darker shade of pink, and as it would happen, those are the spots that inevitably become those splotchy spots?!?!?! And, yes, this has happened on new mesh, or mesh that's been used once before. I do degrease my screens with Ryonets Degreaser formula, as well as scrub it down with an abrasive scrub pad. But, I haven't used any type of abrader solution, as I wasn't aware that one was needed??? I was under the impression that the abrading part, was being taken care of during the degreasing process. Now, let me say that from what you've said about the emulsion not adhering to the screen, sounds EXACTLY like what's going on here. I thought the same thing, I just didn't know the HOW'S, and WHY's of the issue. What's more, I'm completely in the dark, as to how to fix it??? So, if you have any ideas on how to solve this enigma, I'd LOVE to hear them, plus be very appreciative!!! Again, I can't thank you enough, for taking the time out, to help me out with this problem. I can't tell you how stressful it is, to see those splotches pop up again, and again, and again, and...........Well, you get the picture. But, yeah, if there's any more info. you need from me, please, don't hesitate to ask. Countless thanks and cheers \m/

[Shamax]

Good to hear bar from ya, Laced, and cool to hear from someone else that's actually heard of Njiqahdda

Looking over what you've posted, there's a couple things I'd recommend:

1) Continue to degrease your screens using Ryonet's degreaser, but also look into a decent abrader solution. I've currently been using "The Green Stuff" from Ryonet (got a bottle free with an order last year) and it's a combination abrader, dehazer, and degreaser which I use for 1-step mesh preparation. Listening to Jonathan, I now know that I probably *shouldn't* be abrading each and every time, but this stuff works well, and it smells great so it's a good fit for me.

2) When coating your screens, don't go back over them to take off the excess. Invest in a better scoop coater if you'd like, and take note of the two edges on it. One should be slightly more round than the other. The rounder edge will leave a thicker coat of emulsion, which means a thicker stencil, which means more ink will be laid down on each print. Do a single coating pass on each side of the screen and try that.

3) For washout, you shouldn't have to use too much water pressure. Again, I just use the faucet on my tub and use my hand to block the flow when I need or want a slightly higher power spray.

If I had to hazard a guess, I'd say coating process is probably what's contributing the most. A scoop coater you're more comfortable with and doing a single pass with no scraping off would be ideal, I'd think.

[Catspit Productions]

I’m going to lean toward agreeing with Andy I think he made excellent points there but you’re in luck.

I think these two new videos form this week will do the trick for you. Especially if you agree it may be an emulsion to mesh adhesion issue.





Abrading the mesh can only be done with a mesh abrader. It’s a micro grit formulated for screen printing. The first video above explains that more. As for the splotchy spots that stay discolored I am unsure what that could be unless it is something from a previous use. If these are news screens then you should post an image of those discolorations. I don't know why you would get this on new mesh.

Most of the time issues with humidity during drying will cause dwelling. I don’t see dwelling on your screens. Dwelling is when the emulsion forms a buildup in one spot like a droplet and creates an emulsion dimple on the substrate side.

Most scoop coaters have two “blades.” There is a thicker one and a thinner one. Use the thinner looking edge of the scoop coater. What mesh count is this?

Lower mesh counts hold more emulsion. I might try a better emulsion as well.

[OffsetnScreen]

What around the household can be used as a micro abrasive that will degrease and abrade mildly before imaging a new screen? Soft scrub?...Lava soap with micro pumice and a soft nylon brush perhaps? The screen will be used for the rhino method, yes, I got a nice halftone image, cant wait to put it on the screen n try it out...peace

[Catspit Productions]

Yes, maybe something with the smallest grit particle possible. Perhaps Softscrub would be best as it is designed to abrade but not damage or scratch. Then you’ll need to use a pure soap without additives like conditioners or oils. So you can abrade but you will need to soap the screen to make sure no Softscrub is left anywhere.