Over the last couple of months, a weird new problem has arisen in my screens. Often when I reclaim a screen using reclaimer chemical in my sink and my spray hose, there is anywhere from one to a dozen tiny spots of emulsion left, usually just the size of one opening in the mesh. I end up having to powerspray them out, which takes up too much time. If I don't get them out and reclaim the screen perfectly, I run the risk of having one of those stubborn little dots show up in a stencil, which means I have to do it again. Sometimes during reclaiming or washing out, blasting the blockage with my spray hose will knock it.
Has anyone had a similar problem? Anyone have a solution, or an idea of what causes this? I've cleaned my exposure unit, thinking that little bits of junk are creating pinholes, which don't get washed out, and harden, but I would think that washing out the screen would give pinholes a chance to wash out as well.
Thanks in advance to anyone who can help me solve this problem!
I think you'd benefit from using a haze remover in your reclaim process. This should remove emulsion and/or ink residue from the screen and also act as a degreaser for you too.
I saw Sveldge somewhere defined as a single hole in the mesh. I'm not sure where I saw it, maybe Screen Printing Magazine. It's pretty obscure, even for a screen printing term.
Bernard- I just reclaim in a utility sink with emulsion remover and a wash out hose. That's what I've been doing for two years and this problem of blocked sveldges has only started in the last couple months, so something must be different, I just can't figure out what. I just took 10 screens out back to powerspray to blow out all those little bits. And as for haze remover, I just do that occasionally when the screens get real ugly. I try to not to do it to screens very often because occasionally it kills a screen. But anyway, I want to nail down the cause of these tiny dots so I will be able to just reclaim like I used to, then dry and coat, instead of reclaim, drag out the power sprayer, power spray, dry, coat... If I didn't have this problem then I wouldn't have had to spend 45 minutes today outside in the sun sweating and spraying...
Bernard- I just reclaim in a utility sink with emulsion remover and a wash out hose. That's what I've been doing for two years and this problem of blocked sveldges has only started in the last couple months, so something must be different, I just can't figure out what. I just took 10 screens out back to powerspray to blow out all those little bits. And as for haze remover, I just do that occasionally when the screens get real ugly. I try to not to do it to screens very often because occasionally it kills a screen. But anyway, I want to nail down the cause of these tiny dots so I will be able to just reclaim like I used to, then dry and coat, instead of reclaim, drag out the power sprayer, power spray, dry, coat... If I didn't have this problem then I wouldn't have had to spend 45 minutes today outside in the sun sweating and spraying...
You've gotta love this profession A least it's better than doing it in snow in winter. Has your emulsion or exposure changed?
No, same emulsion (Ulano qt-discharge) and same exposure time/unit.... I windex'ed the glass on my exposure unit a couple of weeks ago and now I keep a big shirt on top of the glass when it's not in use so that the rubber blanket isn't touching the glass.
And I have reclaimed screens kneeling in the snow, wearing a full winter outfit, shoes getting wet and toes getting real cold.... Ah, the old days. How I don't miss them. Working in a laundry room with a terrible table, constant problems, crappy ink, heat gun to dry shirts...
Maybe it is the emulsion. I'm not sure when exactly these dots started appearing and giving me trouble, but it feels like it has been a couple of months. I opened and mixed this gallon of emulsion almost exactly two months ago. Does anyone think that the emulsion could be funky and causing sveldges to be blocked during washout and reclaiming? I don't know the science of emulsion well enough to have an idea if it could be related. Hopefully Greaves will pop in and tell me...
I still have about half of that gallon left because it's been slow and I haven't been making as many screens as I used to, but it's past its six week shelf life, so if there is something funky with the emulsion, I'll order a new gallon then toss it...
I've experienced this type of problem in the past and it was a diazo emulsion and only occurred in summer, so it was somehow heat related. Try a pure photopolymer and see if that occurs then.
I actually have a sample quart of that emulsion that the nice guys at http://westixonline.com Westix sent to me a while ago. I should try it since this emulsion is acting funny and getting past its shelf life anyway. My only concern with the Murakami is the need to harden or overburn screens. But overburning a screen for a couple minutes is better than spending five minutes fruitlessly trying to get the little dots out of the stencil.
That must be to increase water resistance? Try exposing as normal, wash out and dry then post harden, if you have to. They also have a hardener that can be post exposure applied, but I think that makes the stencil permanent. As is is good for plastisol.
ok, thanks for all your help, Bernard. It's interesting that you had the same little blockage/dot problem in the summer time. Maybe it's the heat but I don't understand the dynamics of it. But tomorrow I'll open up that Murakami and coat some screens and see how I like it. I haven't been busy enough to go through a gallon of the Ulano within the specified six weeks, so it's better to use something that has a longer shelf life.
Single blocked mesh holes ("sveldges") 
Re: Single blocked mesh holes ("sveldges") 
A least it's better than doing it in snow in winter. Has your emulsion or exposure changed?
