Emulsion number of screens vs - solids content

[Prosperi-Tees]

So I am trying not to spend the 4K in upgrading our blacklight exposure unit to LED so I am looking at emulsion choices to speed up the process with what we have. Currently using Murakami SP1400 (42% solids) exposing at approximately 5-7 minutes. I am going to change emulsion but wanted to know what is the most cost effective choice. I know to get the fastest exposure I need a pure photo-polymer. Do higher solids content emulsions equate to more screens coated per gallon? Seems logical to me that it would. I also would like to have an emulsion with good exposure latitude. I am currently looking at Ulano Orange (44-46% solids) and Murakami HVP (42% solids) which are about $65 per gallon versus the $34 per gallon of SP-1400. Anything else I should look at out there?

[tonypep]

CCI VPR........my shop we were at 5 secs @ app $46 per gal

[Frog]

I don't know about the relationship of high solids and yield of number of screens coated, as I merely prefer the feel and coating results I get from high solids.
For the last few years, it's been PFX-HV from CCI and its 47% solids.
Price can vary, but I generally get it from them at about $65. With a rep, there is a little room for them to fudge.

[ericheartsu]

vpn is great!

[mimosatexas]

Not sure about solids count and screen quantity per gallon, but slightingly off topic...

I used HVP for a long time and was very happy with it, but seeing the how well it holds detail and it's durability, SP1400 blows it away in my opinion and is worth the longer exposure time.  I was losing the smallest dots and having fine lines blow out on higher meshes with the hvp during washout after exposure (on occasion), while with the sp1400 I have literally no issues and with my setup it has allowed me to use 55 lpi and do much finer detail work. 

Is there a PP emulsion that holds significantly better detail than HVP?  Price doesn't matter as much as regaining the quick exposure without worrying about durability etc.

[Dottonedan]

Do higher solids content emulsions equate to more screens coated per gallon?

I would say no, that makes no difference. One can use the highest solid content, yet coat heavier or lighter than another person...and faster or slow...or more times on a side or overall...than another shop. So that "high content" alone, doesn't equate to more screens.




I am not nor claim to be an emulsion or screen coating expert nor extremely experienced at it. I just seem to understand some basic principles. Thats my disclaimer.



From what I understand, the basic or most commonly used factors in the decision of Pure Photopolymer or Dual Cure are three things.


1, Typical job quantity. For example, do you print an average of 50 shirts or 5000. The 50 quantity shops may choose PP for economical reasons since the DC can be more costly due to it's quality properties (higher solids) etc. The higher quality from Dual Cure also produces longer production runs without break down, justifying the slightly higher cost over PP.


2, Image/edge definition quality. The higher the solid content among other things, the better the edge definition. Your DC emulsion will typically be sturdier, as well as provide a more cleaner, more crisp image edge. These differences can be miniscule and the benefits to me, may not be the whole reason I choose one or the other.


3, Water base inks or Plastisol.  I don't know much about the differences other than the basic info that Pure Photopolymer breaks down faster on press when using water based inks.




mimosatexas,  Again, I am no screen rm expert. But I would imagine that if you are able to blow thru small areas of your emulsion then (those high mesh counts) you had issues with... may not be at (the most optimum) exposure time yet.  Any truly cured emulsion will hold up very well to water pressure (unless it is excessive) such as using a high pressure sprayer at needle point precision (not that this is what you were doing). Even the properly cured emulsion has a limit as to how much pressure it can hold up to. These are basics and may not be your issue in that case. I'm just stating the obvious and reaching, but over all, I imagine that no matter the emulsion type, (if it's cured), it's cured.  If you are able to break it down...with common fan pressure in your thin lines and fine halftones, then it may not have reached an exact exposure.


Using art for testing exposure (that falls into an extreme area), can be the best gauge.  Recently, I used a sheet of 3% dots at 45lpi, covering my entire print area. With this, any imperfections in the process can be more easily revealed. For example, at 3% dot, covering the max print area, you can start to see the imperfections of your mesh stretching. These dots are all at a specific angle across the board. So when they lay on mesh that has distortion...it shows itself easily. You might see large patterns of rainbows in different areas of your mesh. If using your typical situation, e.g. larger dots (and in smaller areas) as typically seen in art, you may not be able to see that your mesh is actually interfering with your smallest dots.


In addition, the larger field of view of (3% dots across the entire print area) makes it easier to see where you are holding and where is blowing out when doing exposure step test.  If you reach a point of great dots, no slime, fully washed out, and can't blow these out, THAT then, is your optimum exposure and it's your exposure for every other type of art (solid letters, thin line work) as well.  Many people try to use steps of 10,20,30 etc. for an exposure gauge but often complain they can't hold smaller dots later on. This is why. They haven't yet set themselves up to expose the smaller dots as the target for proper exposure.

[Printficient]

Not sure about solids count and screen quantity per gallon, but slightingly off topic...

I used HVP for a long time and was very happy with it, but seeing the how well it holds detail and it's durability, SP1400 blows it away in my opinion and is worth the longer exposure time.  I was losing the smallest dots and having fine lines blow out on higher meshes with the hvp during washout after exposure (on occasion), while with the sp1400 I have literally no issues and with my setup it has allowed me to use 55 lpi and do much finer detail work. 

Is there a PP emulsion that holds significantly better detail than HVP?  Price doesn't matter as much as regaining the quick exposure without worrying about durability etc.

Xenon Nova holds more detail than I have ever seen.  It was designed as a high detail emulsion.  57% solids.  Designed to print installation instructions on pace makers.

[mimosatexas]

And how does the exposure time compare to something like HVP?

[mimosatexas]

Great post Dan.  I have tested the exposure in a number of ways and I'm confident it is correct or as close to correct as I can get with my setup.  I am still using a 1k MH though, and it isn't a screen printing exposure specific bulb.  Definitely not ideal, but hopefully that will be fixed shortly with an upgrade to a 5k olec.  The issues I see are strange.  It isn't an issue of detail loss or undercutting when using HVP, and the emulsion isn't simply getting blown out.  Instead, what happens with some regularity is the point of a long thin spike in some text for example will separate from the mesh.  The emulsion is still one piece, but the end has come off and is sort of hanging off the mesh in a way.  This is at a very very small level.  The same film/screen mesh/etc with the SP1400 and that point is solidly stuck to the mesh, no issues.  It's like the emulsion binds to itself fine but not the mesh.

[ABuffington]

For HVp and SP1400 users.  If you see details peeling away you need a little more exposure time.  This actually is my test to know during the development process how complete the exposure was.  I have converging thin spikes on my emulsion exposure calculator that I try to rub off.  If they don't rub off or peel away at the tips I know I have decent exposure on the squeegee side.

Resolution can be controlled on both emulsions with EOM.  If you are printing halftones try a 1:1 dull edge coating. Still not seeing the resolution you think should be there? Switch to the sharp edge and coat 1:2 to lower EOM, or on the 1:1 perform a clean coat on the print side to reduce EOM.  If you see pinholes during automatic production you may want to increase EOM slightly.  This is where auto coating machines pay off.  You can fine tune the EOM by mesh and coat the exact same thickness everytime.

Like Dan says, a lot depends on who is coating, and speed, edge of coater, angle and temp at coating time will affect the EOM.
We sell thickness gauges to dial this in.

Typically for Discharge and HSA I shoot for 10-12% EOM.
For Plastisol I can lower this to 8% on the base and 5-6% on overprints.  A lot depends on the art, solid areas vs halftones.

Which is more important?  How many screens you can coat? or the quality of your print and non-stop performance.  I was in a shop yesterday who shall remain nameless where they had called me in for breakdown issues.  I find out its not my emulsion, but I do notice that in a span of 30 minutes all three presses needed to be stopped for pinholes to be taped out and maybe 20 shirts were printed while the staff used this opportunity for a break while the press op was under the press on all screens adding tape.  So for clients like this I always ask, which is more important?  running non stop or constantly repairing pin holes?  Needless to say they are back on SP1400.  If it aint broke don't fix it.  Cost vs Price, you can pay me now or pay later, but you will pay.

[Printficient]

I would put Nova and QXL up against anybody.  When I ran a shop and was using Nova I ran 5000 pieces with no breakdown at all.  The screens were coated with 1 pass only on the substrate side.  The press was an MHM 4000.  The point I am making is it can be done if you know what you are doing.  I do agree with Al though in that most times better safe than sorry and do some research as to the cause.  Most of the time it is not in the emulsion but the processes that come before.

[Prosperi-Tees]

Surprisingly I have little issues with pinholes seeing that I have no darkroom and no real enclosed place to keep my screens.

[ABuffington]

Insta light safe screen room: Coat at night, stack in clean area, put them in black trash bags before sun up.
Sure gets you to work on time to make the coffee.

Al