emulsion

[JBLUE]

I'm fixing to go down this road myself and planned on adding diazo to our Aquasol HV.  It has very good water resistance already and diazo + hardener when needed sounds promising.  Almost all of Murakami's photopolymers are rated for discharge- it sounds like photopolymers are a no-go for discharge from other brands but anyone have actual experience with Murakami's and these inks?

Maybe try adding diazo if you are hell bent on staying with one emulsion.  This will change expo values, give it a shelf life once sensitized and give it a little more latitude in addition to adding water resistance.

Myself, I'm not at all opposed to having two emulsions for the different inks as you can choose different colors and have a fool-proof visual of which screens are for which seeing as the coating methods and overall processes are going to be different for each. 

Most suppliers and mfg's are overly generous with emulsion samples it seems, we still have quite a few qt.'s that I never even asked to trial.

We use Murikami as well. For playing around and testing I just throw hardener straight on our TXR coated screens and it holds fol a pretty good amount of time while testing. I have had good results HVP using Diazo on runs of up to 1k. I have not run any discharge prints over that yet.

[mjrprint]

I'm fixing to go down this road myself and planned on adding diazo to our Aquasol HV.  It has very good water resistance already and diazo + hardener when needed sounds promising.  Almost all of Murakami's photopolymers are rated for discharge- it sounds like photopolymers are a no-go for discharge from other brands but anyone have actual experience with Murakami's and these inks?

Maybe try adding diazo if you are hell bent on staying with one emulsion.  This will change expo values, give it a shelf life once sensitized and give it a little more latitude in addition to adding water resistance.

Myself, I'm not at all opposed to having two emulsions for the different inks as you can choose different colors and have a fool-proof visual of which screens are for which seeing as the coating methods and overall processes are going to be different for each. 

Most suppliers and mfg's are overly generous with emulsion samples it seems, we still have quite a few qt.'s that I never even asked to trial.

I tried discharge with Murakami Photocure Blu and it started to break down after 10 minutes.

[inkman996]

Cant you just add extra diazo to any emulsion to get a harder stencil? I know I have dozens of them little bottles lying around that I havent used.

[chubsetc]

I have use chromablue coated 2/2 and post harened in the sun for a couple hour and been able to print 100 2 color fronts and backs ganged on the same 2 screens without a problem.

Hmm... I have ChromaBlue and I did a post cure in the sun for a couple of hours and then after printing platisol (or on some screens not even printing) I was able to blow out the emulsion with a VERY cheap pressure washer.

Is that normal?  I've been meaning to mention that but have forgotten.

I've been using chromablue for a few years and no issues with a weak stencil with plastisol.  I do feel it washes out much easier after exposure than the other photopolymers i've used but haven't had issues after drying the screens.

[Gilligan]

Yeah, it didn't break down on press or anything.

Just didn't take much to push it out once I put the water to it.

[Prosperi-Tees]

Pure photopolymers in my experience are super easy to reclaim because they have no water resistance so it soaks it up quickly and breaks down quickly.

[Frog]

I've been using them since first introduced by Murakami 20 years ago or so, and have found that some do dissolve more than others. They all blast out fine when properly exposed, for the most part, but some come off more as a solid, while others just melt. Fortunately, most of us are not making the situation worse with solvent inks and petro-chemical cleaners. Those can really lock in an underexposed emulsion, similar to the hardeners sometimes used by choice.

I must say though, that I have never used a tank. This is all with either pouring or spraying on emulsion remover, agitating with a brush, and blasting.
Heck, for many years, I didn't even use my pressure washer with Chromaline PL, but rather just the same garden sprayer type black plastic nozzle that I use for developing. (I have never gotten into using my pressure washer for developing either)

I have used Murakami Aquasol HV on Plastcharge, generally for smallish runs of 72 or less with only post development additional exposure hardening, a feature reserved for photopolymers. I can't imagine that a couple of hours in bright sun would do a lot more than fifteen minutes though. That sun is one powerful lamp! Then again, I am constantly learning.

[Printficient]

Xenon's Nova a photopolymer with hardener and diazo is lasting for 500+ prints with absolutely no sign of break down.  This is also our best detail holding emulsion.

[ebscreen]

I can't imagine that a couple of hours in bright sun would do a lot more than fifteen minutes though. That sun is one powerful lamp! Then again, I am constantly learning.

I realized that yesterday when we had some screens out in the sun. We usually leave 'em out for a few hours, in this case we needed one pretty quickly.
Thought about and realized that even a minute is probably good.

[Gilligan]

Yeah, mine only stayed out for hours because I ran some errands while they were out.

[ZooCity]

They say you don't need much more than 2-3 times the expo value for post exposure but that depends on variables like stencil thickness, etc.  When there's no sun or I don't feel like putting delicate screens in unsafe areas I put them back in the expo unit, squeegee side down for 60-120 ltus.

I agree that pure photopolymers are, on the whole, a little 'softer'.  Yet, Aquasol seems to be formulated a little different and is the only emulsion we've had that allows a pressure washer for resolving, which I greatly prefer.  Like the other pp emulsions, Kiwo One Coat, etc., the Aquasol is very 'on/off' with a narrow latitude but is sort of harder and more brittle than the others.  This can be a pain with thicker stencils and push stroking with sharp blades and higher off contacts as the emulsion tends to crack rather than flex and you need to tape your squeegee corner lines (even on rounded blades) or some ink can get through even with plastisol but I'm sure it's a trade off with these characteristics, nobody meant to formulate a brittle emulsion, they were probably going for the water resistance and that was a side effect, and I can live with the brittleness if it means I can pressure wash to resolve.

I wanted to remind everyone that Murakami has some very in-depth tech material on their site regarding screen making for wb/discharge, pp presentations and even a video.  Check it out:

http://www.murakamiscreen.com/tools_screen_room_designs.html

[ZooCity]

Oh and too much time in the funshine can degrade your mesh threads so no need to go overboard.  Dryness is probably more or equally important. 

[alan802]

I have use chromablue coated 2/2 and post harened in the sun for a couple hour and been able to print 100 2 color fronts and backs ganged on the same 2 screens without a problem.

Hmm... I have ChromaBlue and I did a post cure in the sun for a couple of hours and then after printing platisol (or on some screens not even printing) I was able to blow out the emulsion with a VERY cheap pressure washer.

Is that normal?  I've been meaning to mention that but have forgotten.

Nope, shouldn't be that easy to spray out unless they are underexposed or it's a thin stencil.  On our higher mesh counts with thinner stencils, you can wash the emulsion away without using an emulsion remover but it takes some work.

[Frog]

 ...on our higher mesh counts with thinner stencils, you can wash the emulsion away without using an emulsion remover but it takes some work.

Not a good practice as you may find your mesh losing tension. (Though of course you, with your re-tensionables can crank it up again, not only is that more work, the mesh must have a spot at which it doesn't want to stretch any more. Then, this practice could result in a tear. Remember that those high mesh counts are pretty fragile.