My halftone exposure test results

[Gilligan]

200 mesh coated 3:1 round edge, one set of blocks at 25 LPI 25 degrees and another at 35 LPI 25 degrees.

http://tinyurl.com/6suqnb4

they look pretty good if you ask me.

At first I washed them out with pressure washer but just using regular water pressure (power turned off)... good fine point stream and I got real close.

Then the 90% black could use a little more clearing up (just a tad) on the 35 LPI... so I figured, let me see what happens and turned on the pressure washer.  Oops.

My question about that though is, was I asking too much or should I have been able to hit the screen with the pressure washer all the same?  I'd think that if I'd have left it alone I'd had gotten it washed out to 95%+ perfection and could have tossed it outside for a "post cure" (granted this was at night so that wouldn't work)... and drying/sun UV would have locked in what I had and it would have been good.  Is it possible that he screens were completely dry through and through?  I dried them with a fan for a couple of hours then placed them in a box for the last couple days.  I know this can hold moisture but it's what I got right now.  I could scratch off some of the edge drips after washing out... but it is thicker there.

Sorry that the pics aren't very well labeled or clear so it can be hard to see which is 35 and which is 25.  I will bring home the flip scanner tomorrow and get a better set of images.

It looks like the 25 LPI stuff was REALLY solid and I could PROBABLY use the 35 LPI as well.

What is everyone's thoughts?

Oh, I also neglected to dehaze/degrease the screens... last step was ER2 and a good rinse.

Fixed server issues... should be VERY fast now!

[jsheridan]

What kind of film are you using.. looks like you may be able to expose a little longer for a better burn through.

This reminded me I needed to run some test films myself. Picutres after results.

[Frog]

Now Gilligan, besides learning what you can hold on your screen, when you get a screen that you feel is successful, use it to print as you normally would, and then compare the printed results to your art (or halftone samples) to get a better idea of how much dot gain you get.
In fact, you could even compare your film with a somewhat controlled print on paper to learn how much that adds to the dot gain. Different films, different inks, different settings all can affect dot gain.

[squeegee]

You should be able to hit your halftones with full pressure, in fact I think that is a testament to proper exposure.  That said, with a bunch of variables thrown in it may not always happen (inconsisent eom, humidity in emulsion, light source, film density, quality of emulsion, etc) so use the lower pressure if needed, as long as your image is good for printing afterwards.  The more you eliminate the variables, the easier it gets.  Try 1.5 times the exposure you used and if over exposed work your way back.  I'd be inclined to coat 200 mesh 2/1 sharp edge, you don't need a big EOM for that mesh and will make exposure quicker and easier.

[Gilligan]

Andy, I planned on printing with it... I left it out to dry, need to put it outside but I'm not there... hmm, maybe our maid will go by today and I can get him to do it.

jsheridan, Fixxon's waterproof films printed with Epson WF1100 using heat press pigment inks from inkjetcarts.us... They are pretty dark but I don't have much to compare them with.  I followed some suggested settings from some guys on t-shirtforums.com and they seemed to come out well.  I'll see if I can take some pics of my films also.

Squeegee, absolutely agree...  those are a lot of my variables.  Inconsistent EOM (I'm so new at coating screens... ZERO confidence in what I do... but I try), this is one reason why I went with 3:1... I've coated 3:1 before and have exposure time test... so I had a CLUE of at least a partial part of the variables... trying to eliminate what I could.  Humidity in emulsion, Yep... it's south louisiana!  We got humidity for sure!  That is one downside to a thick EOM harder to get the moisture out.  My buddy coats 1:1 dries with a fan for 10 mins and burns with a tube exposure unit! Light source, that should be good... 400W MH bulb.  My only weakness there is I have no exposure box and I ghetto up things to get the lamp warmed up.  I THINK I'm protecting the screen from UV good enough till it's warmed up... again, doing what I can to remove variables (bulb warm up).  Film density, I'm unsure... it LOOKS good to the naked eye... but with no AB to compare it to it's kind of hard to say. Quality of Emulsion, well, it's a fairly new container of Chromaline Blue.  Should I be stirring this stuff up before I put it in my scoop coater?  It's premixed but it always looks like it's got a bit of swirlyness to it when I pop the lid.  I hate to generate bubbles though.

So I should be able to wash out a screen with FULL pressure washer pressure?  Hmm... obviously that didn't happen here.  I've read about people doing that for stubborn exposures but I always assumed that was a bandaid fix for an improper exposure to start with.  SHOULD I be using that method or SHOULD it washout with regular hose pressure?

I'm exposing for 45-47 seconds with these screens... I was exposing 2.5  mins with 158 mesh with 2:1 round edge.

Those test are on this thread:
http://www.theshirtboard.com/index.php?topic=1748.msg18692#msg18692

Please don't take any of what I said for me knowing anything.  I don't think it sounded like that but I want to make sure everyone understand I was only clarifying what I have DONE, not what I THINK I need to do.  I'm COMPLETELY ignorant and looking for any and all suggestions!

[Gilligan]

Moved the files to my server here at work... obviously the house is having some speed issues I wasn't aware of.

More to do when I get home... YAY! 

[inkman996]

A properly exposed screen can be developed with full pressure. It is the only way I do it. But maybe from the look of your pics you might be lingering with the water jet. When developing always keep the water moving hover on a spot to long and you can bet you will burn right through the emulsion. Also it is good to move closer and farther away with the pressure washer, big wide open areas I get more aggressive, fine halftones i back up a bit.

[squeegee]

Should I be stirring this stuff up before I put it in my scoop coater? 

So I should be able to wash out a screen with FULL pressure washer pressure?  Hmm... obviously that didn't happen here.  I've read about people doing that for stubborn exposures but I always assumed that was a bandaid fix for an improper exposure to start with.  SHOULD I be using that method or SHOULD it washout with regular hose pressure?

Stir, yes I would.

Is full pressure necessary?  No, but whatever works for you, I use full PW pressure all the time (like 12-18" away), I know when details fly off the mesh that the exposure needs a tweak, but I have bulbs designed to harden emulsion (certain UV spectrum output), yours though is what exactly?  Maybe it will never fully expose emulsion without undercutting, who knows?  I say take your exposure times 1.5 or even 2 times what you think will work and see what happens, work at overexposure first and then work backwards, I think you'll find your limitations faster that way.

One way to coat more consistently is to build a wooden stand like an eisel that's on a slant, hold the coater with both hands and flip the screen vertically between front and back sides of the screen.

[Gilligan]

Ok... I brought the screen to the office today (I kept forgetting the scanner.

It's light, but sharper.

Same link:
http://tinyurl.com/6suqnb4

But the ones titled "Scan***"

The first set scanned was the 35LPI so it goes in order up the screen moving bottom left to bottom right (overlapping the middle row) then top set of the 35LPI then it moves on to the 25LPI.

4 scans each.

[Gilligan]

Being realistic should I expect to hold 90%/10% perfectly or do I need SUPER films put out by some killer DTS system or something?

[blue moon]

Being realistic should I expect to hold 90%/10% perfectly or do I need SUPER films put out by some killer DTS system or something?

if you can hold 10%-90% that is an EXCELLENT start!!! Get a 50x or so magnifier and look at the stencil. The edges should be sharp and should span the threads without being blown out. Run the exposure test and find the best time. There might be a range of times that produces good results, I generally go with the shortest, but YMMV. . .

My guess is that you will have to increase your times significantly. I am at almost 2 min with a very fast emulsion and a MH light for similar emulsion thickness as what you seem to be describing (just a guess here). Also, we wash out with the pressure washer without exception! It gives us better consistency and it helps open up the smaller dots. Longer times should help with your dots blowing off during washout.

Your goal should be to get down to about 5% or so. Going any lower is pretty difficult and for the most part not necessary. Anything over 90% is going to be pretty irrelevant considering the dot gain.

good luck, any keep bugging us here. We'll help you sort it out. As it is, you are already doing what a good number of shops can't. . .

pierre

[jsheridan]

I made tonal plates from 5% to 90% using 25 - 30 - 40 -50 LPI all at 22.5 angle with elipse dots.
Stuff for printers film with Dye inks from my R1800 with accurip on more ink with 2 drop density @ 1440x1440

Shot on 205 newman mesh with Ulano WR925 coated 2:2 round and burned for 8 minutes* with High-ouput Blacklight bulbs.

Only the 25 and 30 plates washed out completely from end to end with some funny oval-esk moire in lower tonal ranges.

The 40 lost some dots in the 90% range

The 50 lost detail at both ends with some dots washing off in the 90% and over exposed to the 8% range. This I can change by adding some dot weight in accurip if I know I'm going to be doing this type of 1/2 tone work.

I have to fire up the oooold computer that has Freehand on it and re-print some old test films I made 10 so yrs ago. Every angle and tone % one would need on a film. Just alter the LPI per film and you have the best test plate a printer would ever need.




*note on exposure. Ulano uses syrup for diazo and I mixed my little bottle more than ever before. As a result of that,  my normal exposures of 3-5 minutes increased to 8-10 from the increased diazo in the emulsion. lesson learned for mixing that syrup.

[Prosperi-Tees]

*note on exposure. Ulano uses syrup for diazo and I mixed my little bottle more than ever before. As a result of that,  my normal exposures of 3-5 minutes increased to 8-10 from the increased diazo in the emulsion. lesson learned for mixing that syrup.
[/quote]

What do you mean by this? Mixed more than before? I ask because I just bought a gallon of 925WR so if you have any tips on this emulsion that would be great.

[jsheridan]

Ulano's Diazo is in a liquid syrup form vs others powder form. It's still the same product it just requires warm water thoroughy stirred with the included wooden stick vs just the shake with the powder.

I just happened to notice when I looked in the bottle after pouring it off (habit from powder that liked to cake in the bottom) and I say some syrup left on the bottom. Added a few drops of water and stirred it up and added to the pot. Went from it's purple to a deep shade when mixed. First screen burned I added a minute but was underexposed until I went 8 minutes with a 200. Before I mixed the diazo really well I was shooting at 3 minutes.

[DILLON]

...Stuff for printers film with Dye inks from my R1800 with accurip on more ink with 2 drop density @ 1440x1440...

You have your droplet density @ 2? I have mine @ 12