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screen printing => Screen Making => Topic started by: blue moon on May 03, 2013, 07:26:33 PM

Title: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 03, 2013, 07:26:33 PM
attached is the halftone test file for the screens and films.
This is what we use to calibrate the film output and see what we can hold on the screen.

Anybody interested in getting their RIP output calibrated can send the films to me for readings. I check it out and email the values to be entered in the RIP to produce calibrated output. My time is limited, so I can commit to one or maybe two of these per week. Films will go in the queue and will be checked on first come, first served bases.

If using it to check the screens, see what is the smallest percentage that opens. It is OK to spend a little bit more time washing those out, as we work harder in those areas too. What matters is that you can repeat the results.

For anybody sending the films to us, I very strongly suggest printing two copies and saving one as a reference. It is also a good idea to actually fill out the information on the top (instead of leaving our info) so you know the settings used. I've found that over the years we switch this and that and I have reference films that I don't know what's on them. Gradient and opacity should look the same. If there is any variation, there is a problem with your software.

45lpi is a good place to start as it is in my opinion a minimum needed to produce good prints (7-85% should be good). At 45lpi those numbers should be achieved pretty easily. Step up is 55lpi in 5-90% range and to get really good anything at 55 or smaller in 3%-95%. 230 mesh for 45lpi and 305 for 55lpi. These are guidelines, not rules, so feel free to experiment.

Let me know if there are any issues with the file. I have it as an ai and eps if needed.

pierre
Title: Re: Halftone test file for the films and screen
Post by: blue moon on May 03, 2013, 07:30:08 PM
few things to look for is any banding in the gradient strip, jaggy transition from halftone to solid on top of the strip and closed in dots at 90% or more. Your film output device should be producing very small holes at 99% whereas 100% should be solid.

traditionally, ghostrip produced 60%+ at 50% and AR is usually above 70%. This is based on tests with our equipment and other ppl sending films for reading.

pierre
Title: Re: Halftone test file for the films and screen
Post by: blue moon on May 03, 2013, 07:42:49 PM
and here is ball park what a 50% image should look like. The rows should be slightly closer together, but the distance (end to end) between the dots is about right.

If your dots are joining before 70%, the dot size is too big.

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 03, 2013, 07:54:54 PM
Pierre,

I applaud your willingness to help here. You my friend get 10 respect points.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 03, 2013, 08:17:45 PM
Well I haven't looked at my printers dots in a while. I think I need to calibrate it a little (not as smooth as they should be)

Here is my 50 and 45% dots. I am off but not as much as i figured. Still need to get my rip set perfect for my new printer. These photos are at 800 percent magnification. I know a little over kill. They are also blurry.

Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 03, 2013, 09:16:51 PM
that looks like a round dot to me . . . do you have it set up as elliptical?

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 04, 2013, 12:45:28 AM
They look square to me. It was set to elliptical. It was done with ghost script.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on May 04, 2013, 08:35:16 AM
Jon,  is your printer using toner or digital ink?  Looks like toner. Pretty undefined edges.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: GaryG on May 04, 2013, 09:59:26 AM
That's on film correct?
What printer?

Looks like --white paper-- and texture of it making edges rough
or inkjet ink splatter... Which is pretty normal at that magnification.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 04, 2013, 11:11:31 AM
the round dots convert to squares around 50%. It is not as prominent with the elliptical dots. Here's a picture of our 50% dots produced at high speed settings (they clean up when printed in one direction only).

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: GaryG on May 04, 2013, 11:42:01 AM
Definitely 2 different output devices. It would be nice to know
which ones?

We have a Epson 1900 with 8 cartridges. Specs mentioned smaller
droplet than say a 1400.

Seems ours spatters in-between Jon's and yours Pierre.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 04, 2013, 11:49:35 AM
the image is from the 4800. Dots on the 1400 are much cleaner than the 4800, but it was just too slow and cumbersome to use. going to printing in one direction cleans the dots up quite a bit. I'll see if I can print a test page and take some pix . .

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 04, 2013, 12:32:34 PM
here's the single direction print, it is a little bit cleaner. output is not calibrated for single pass, so the dot size is a little bit different. One big difference is that there are no stray dots and what is there is just a little less bumpy.

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: GaryG on May 04, 2013, 01:03:42 PM
I know the secret to your success Pierre-
You clean up all your halftone edges with an X-acto knife. lol
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 04, 2013, 01:17:12 PM
and the same dots at 2880x2880 . . .
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Homer on May 04, 2013, 01:29:40 PM
P - do you usually print bidirectional? I always thought that was a no-no. I am going to flip my numbers as you suggested and see if that helps with the gains. I cranked up my resolution to the maximum and it cleaned up all the spatter but it still doesn't have a clean defined edge like yours. I'm using the same printer so I suppose that's the difference between Fm and accurip. I'm still loosing it around 90%, it goes straight to mud.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 04, 2013, 02:08:49 PM
P - do you usually print bidirectional? I always thought that was a no-no. I am going to flip my numbers as you suggested and see if that helps with the gains. I cranked up my resolution to the maximum and it cleaned up all the spatter but it still doesn't have a clean defined edge like yours. I'm using the same printer so I suppose that's the difference between Fm and accurip. I'm still loosing it around 90%, it goes straight to mud.

we switched to bidirectional about a year ago and have not looked back. Seeing the difference now, I might go to 2880 single direction for the super high end prints, but will stay with 1440 bidirectional for rest.

AR starts getting muddy in the 90's, that's the limitation of the software (from what I have seen). It can be cleaned up by calibrating, but at the end FM does look better. The question is, how much better?

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 05, 2013, 01:34:21 AM
The dots I posted were 55 LPI with no improvements or edits to the rip. I am using a canon IPF 650.. I ran that print on silkjet film. I took the picture with a USB microscope at 800 zoom laying the film over white paper. Even with all the stray dots the film come out. With smooth dots. The stray dots are so small they don't come out. I have been using filmmaker and the out put dots are much more like Pierres dots. I just ran Pierre's file on Friday real fast  with ghost script before leaving for the day. Film is an area you really need to put some time in. Good dots and dark films make the biggest noticeable increase in print quality in my opinion.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on May 05, 2013, 01:22:41 PM
The dots I posted were 55 LPI with no improvements or edits to the rip. I am using a canon IPF 650.. I ran that print on silkjet film. I took the picture with a USB microscope at 800 zoom laying the film over white paper. Even with all the stray dots the film come out. With smooth dots. The stray dots are so small they don't come out. I have been using filmmaker and the out put dots are much more like Pierres dots. I just ran Pierre's file on Friday real fast  with ghost script before leaving for the day. Film is an area you really need to put some time in. Good dots and dark films make the biggest noticeable increase in print quality in my opinion.


Hi Jon,  I'm not sure, but my guess is that the fact that your dots look smoother when exposed, is telling us that you essentually are losing detail and burning out our smaller dots. This is going to happen to a degree but should not be excessive. It would be more educational to see a good picture of that halftone are printed as well as your lowers end dots to see where you are ending up.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 05, 2013, 05:26:55 PM
I was just referring to the scattered dots in the film they are so small that you really can't expose
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on May 05, 2013, 06:20:43 PM
I was just referring to the scattered dots in the film they are so small that you really can't expose


Thats what I think you are underestimating. If the industry materials (inks, mesh, emulsions) we have available to us can hold the shape of a correct smooth ellipse dot shape of a 3% in a 65 line screen, it's more than possible to hold the contour shape of your rough edged dot. Another example (to the extreme) is if you have a true high quality (Photo film) imagesetter and you run your films faster at 1200 dpi, that dot shape is not (as well defined) as when using 2400 dpi.  Those who control 4 color process prints to a perfection can see the benefits of this 1st in the stencil and 2ndly in the print. How much, is probably not of a concern to the average printer...and of no concern at all to the purchaser but is a factor that is considered often timed by those who win many many awards. I know your not trying to win awards. It was more of an illustration to show that those small (often considered irrelevant) areas of spray...can play a part in your outcome.


Often, we confuse not being able to hold a dot that small (within the screen) or your light source. Actually we can hold a 1% in a 65 line screen just fine (in the emulsion). It's the ability to put it down on various garment weaves (and to what readable pleasant or acceptable degree to the eye) that people question.


So my point is, (and I'm only mentioning this for the technical discussion/benefit of the forum and just general chat) is to say that a rough edged dot shape like in the photo (in my experience) is also playing a part in your image quality. The rough edges add to your filling in at various parts of your tonal range. The outer (smaller fragments of dots) considered overspray (can also literally be held) if you have all of your other processes fine tuned.


If your intent is to under or overexpose so that you get a smoother dot. They contribute more so, to you not holding an optimal image quality than average. It's like using toner and that outer residue that shows up. Most can agree that toner does not give you a well defined dot shape...and so your mid to shadow range where the dots converge-converge faster. Resulting in more fill in (depending on how you handle the rough edges). Meaning, your FIX might be to either over or under expose...yet you might not know why you have done so, but you know you get a better dot shape as a result. This is probably why, but can also lead to shadows filling in or highlights burning out.


As a result, if you make adjustments in the screen burning process to open that up or fill it in more, (in an effort to get a smoother dot) you are also effecting your lower end dots or your shadow tone tones. One way or another, one side is effected. To what degree?  Well, thats all relative but I would guess that will determine wether you can hold a 5% dot better or worse.


What would be the fix?  I donno.  Maybe a better RIP or a different printer. I didn't read all of those details and I'm also not experienced at printing out from toner or inkjet printers and using those rips. I only can see the possible results of what they dot can or cannot do base don shape and density.  A tonal adjustment or linearization would not fix that issue, only add a band aid...but this is the most common fix.


Dot shape is probably the least considered, but you do hear more of edge definition when discussing the quality of various emulsions. This plays a part in that.


It's all often considered overkill for anyone not interested in controlling dots to perfection like Pierre, Rick Roth, Target graphics, Andy Anderson, Mark Coudrey and the like. I just thought I'd share my thoughts on this thread..and that image... and often times, it's not going to be of a concern or even impact the quality that much to the average shop.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on May 05, 2013, 06:31:29 PM
As a side note, It's not like your current dot quality is poor. It's par for the average shop. Most all are using inkjet printers for films. but take for example, Mark Coudrey. If he were putting in a print for a competition, I'll bet he's going to use 2400dpit on his photo film imagesetter rather than the best inkjet printer.


On a scale of 1-10 regarding dot shapes and density.




Yours is a 6 and most seen in the industry. ( average ink jet set up) various rips.
Pierre's is a 8 and much better of course,    ( fine tuned ink jet set up) with a good rip.
Mark Coudrey's is a 10. (2400 dpi photo films)


I'll also say, for what it's worth, that Mark Coudrey also offers ink jet films of a higher calibre than average but still less than the photo film. So it's not like he will ONLY use photo films.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 06, 2013, 10:29:05 AM
just an FYI, Jon did say he uses FilmMaker the same RIP as we do, but the sample was printed through GhostScript. So my guess is his dot quality is significantly better than what he posted to help keep the conversation going . . .

Jon what kind of microscope did you use to take the pictures? I am in a market for one and that image looks pretty good.

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on May 06, 2013, 11:28:55 AM
Yea, I don't wanna come off as a primadonna dot shape guru,  as in (use what I say or you're wrong). It's not that way at all.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: ebscreen on May 06, 2013, 01:23:43 PM
Glad this thread came up. I had tried out AR and FM awhile back and was sold on AR
for some reason, but can't recall it now. I'll give FM another look.

Is FM networkable like AR is?
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: blue moon on May 06, 2013, 01:28:46 PM
Glad this thread came up. I had tried out AR and FM awhile back and was sold on AR
for some reason, but can't recall it now. I'll give FM another look.

Is FM networkable like AR is?

you can share the printer over the network. There is an option to create hot folders, but I have not used it.

pierre
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 06, 2013, 04:08:46 PM
Pierre,

I got the microscope off of ebay a year or two ago. I just did a search there and there is a ton of them. Mine is 20X-800X some are 40X-800X. Mine looks like the picture below. I think I paid $38 for it. Its cheap and has its issues but does a nice job for the price. Its great for looking at and getting pictures of ink deposit and dot shape. Its just another tool to have around.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: JBLUE on May 06, 2013, 04:35:46 PM
I do not use Ghostrip so if this is a dumb question I apologize. Can you linearize that rip?
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 06, 2013, 05:07:28 PM
I do not use Ghostrip so if this is a dumb question I apologize. Can you linearize that rip?

To be honest with you I have never even looked at the settings. It worked so I just went with it. I just looked over everything and there is no spot to linearize it. I have used both Filmmaker and ghost on my  printer and FM does a ton better. FM has a ton of adjustments you can make that will effect the printer. With FM I can make the films super dark with standard ink. It also cleans up the dots. They are tighter and more refined. I think the part that I was not expecting was the dots are smaller. A 55LPI dot out of Ghost is larger then a 55LPI dot out of FM. Not sure if that's a good thing or not. Come to think about it, that maybe from the linearizing that is standard or preset in the rip.  I have talked to Pierre on this and the more you work with dots and adjusting your out put you realize how crappy your films were before. I still don't think the dot shape matters that much at a 55LPI but the darkness of the films and linearizing is the reason to get a good rip. Darker films wash out easier. They keep smaller dots from being overexposed. The linearizing will open up your gradiants so that your prints have more depth. It will also make printing easier and take less time to get jobs to print right.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Inkworks on May 06, 2013, 08:50:17 PM
Isn't the idea to linearize to the printed ink deposit, not the film? Or is that next to impossible to do on a shirt?
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: mk162 on May 06, 2013, 08:55:05 PM
linearization is for film output, dot gain compensation is for printed garment.  My old RIP (that Dan now has) had both.  That thing was awesome.

I don't know why you would need both since I would think that if you tested your dots at 5% intervals 5%-95% that you could test the printed shirt and work from that.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Inkworks on May 06, 2013, 08:58:04 PM
Gotcha, I knew I must have been missing something. :P
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: JBLUE on May 06, 2013, 11:53:57 PM
Isn't the idea to linearize to the printed ink deposit, not the film? Or is that next to impossible to do on a shirt?

You need to do both. Your inkjet printer is going to have dot gain. There is no way around it. The only way to compensate for it is to linearize the printer. This is the first place to fight dot gain accurately. Correcting it before it even gets to the screen is important.Trying to compensate for it in the art or on press is just going to affect the quality of your print.

If you are getting 15% or more gain on the film add that to the percentage of what's going to happen on press and you end up with a mess. You can only do so much in the art before you start making a negative impact on press.

Most would be surprised at how far off their printers are once they linearize.  I was. That 5% dot that you thought you were holding perfectly now is hard to resolve because it was really a 18% dot the whole time.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Screened Gear on May 10, 2013, 09:43:00 PM
Ok I said I would post my FilmMaker dots. These are the same printer (still have not fixed the out of ajustment nozzels need to get photo paper or somthing better then I have for that.)

These are 55 LPI 50% dots. The dots themselves are super dark. If you hold the film up to a light and put your finger between the light and the ink deposit you can verily see your finger (in a solid black area of the file). The ghost rip ink density was lets say 50 to 60 percent black when looking at the light. The Ink with the adjustments in MF is about 90 to 95 percent.  What does that mean? The dots have a really good chance of not being over exposed by light penetrating the ink. This also means I can burn the screens longer making sure the emultion is fully exposed with out the worry of overexposing my design. The darker film also makes washout really easy.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: ABuffington on March 17, 2014, 02:58:21 PM
Just my 2 cents:

If you want incredible dots get a real film image setter.  Those dots are as crisp as you could ever want them.  They are cost prohibitive in both equipment and film costs, but ask some of your top end printers and they will go with image setters, not ink jet for the ultimate films.  However inkjets are the most common film making method, nothing wrong with them, just need to know how to tweak the output.

The stray dots seen in the ink jet halftones are the pico liter dots, typically 7.5pl to 12 pl that the printer uses to build up the halftones..  These dots are too transparent and too small to image on emulsion.  They will either be undercut, or too transparent to avoid burn through.

For textile printing halftone printing is a balance. For me I get diminishing returns as I increase lines per inch.  At 85 line the ink wants to jump across the negative dot of 70-95% and the tonals disappear. Higher mesh counts an help control this but ink opacity suffers.  Increased squeegee pressure to get the halftones to be more opaque just kills halftones above 80%-90%.  The balancing act: Any halftone print should have the following attributes: Good print opacity, reproduction of as many tonals as possible between 5 and 95%, the least amount of squeegee pressure possible to yield good 100% solids and tonals within the base.  With S mesh there is no need for print/flash/print
to get a base.  I do like a dummy screen after the flash to press the tonals flat to accept other halftones printing on top.  Under a microscope a plastisol base plate halftone is a pointed peak of ink, not a nice flat dot to print on.  Flattening them with a dummy screen after the flash means you can get away with less squeegee pressure on the colored halftones.  Discharge White base avoids this altogether, but does suffer dot gain and dry in of finer dots.

For me the optimum halftone baseplate depends on other factors.  a 14 singles low end T is better off with a coarser halftone.  A 20 singles smooth faced t can handle a 65 line. I like 55 or 65 through a 225S mesh baseplate on smoother knits, or a 45 or 55 line through 150S or 180S on coarse weave or darks.

I also like a linearized output.  No tones below 4%.  You can't see them anyway in most prints!   And it is better to print a base plate with minimal squeegee pressure to control dot gain on press.  For me that is a 150S, 180S or 225S.  Tones below 4% do get blocked by mesh threads, going up on mesh count to print dots you can hardly see kills opacity and causes the 85-95% to print solid.  Rather than trying to image a 2-4% dot, try to print a 90% dot.  This is the tonal area that begins solid art to tonal, a crucial tonal transition that looks better when smooth and not an abrupt transition and where dot gain kills most tonals.   

Attempting to hold less than 4% is not easy.  Threads block some of the halftones, an inkjet 2% is a really ugly dot with the pico liter dots barely forming what we would call a halftone.  Plus the shirt fabric as mentioned often can't image it.  Consider that UV poster printers often eliminate these percentages due to the problems in moire they generate.  They print with 380 and 420 mesh, which are hardly t-shirt friendly base plate meshes, and are really, really expensive.

The key test:  Output 45, 55, 65 line 5-95% tonal steps using the correct angles, (see below) .  Image on your choice of baseplate screen(s).  Set up and print on your typical shirt brand or multiple shirt brands.

Analyze all prints for best opaque tonal output capturing as much of the 5-95% as possible.  From here it can be fine tuned for linearization of the film and print.  For film you need a transmissive densitometer that can read halftones.  x-rite eye one is good for this.  For the print, reflective densitometers can get real pricey.  Comparing the 5-95% film to your print and adjusting squeegee durometer, angle, speed, ink viscosity, ink type can save thousands.  That's the beauty of this industry, sometimes all it takes is just making it look good!  Compare the different line counts visually, use what works best for you.

Here is an article on moire and how to avoid it.  Also pages 4 and 5 have a chart with typical Murakami mesh counts and the angles to use.  Choose from the middle of the green blocks of OK angles.  This will allow your mesh capture to be off be a few degrees and not matter.  For any halftone angle to work the mesh must be straight and square to the frame.  Or you can try biased stretch screens stretched to 22.5 degrees or 61 degrees, two common non moire angles.

http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf (http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf)

Al
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: GaryG on March 17, 2014, 09:38:39 PM
Excellent!
Wow, only 28 posts and a wealth of information!!
Keep it coming.  :)

Yes, I remember that chart with 100 different angles- someone was busy. ???
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on March 17, 2014, 10:26:54 PM
Excellent information.  Very good food for thought and should be book marked. I think this is great info for 100% of the shops. Highly professional, well thought out information.

At the same time, (while not taking one thing away from your contribution), there are those that make up maybe 5% of the industry that do use the 380 and 420 and higher mesh, that do shoot for the 1-2-3% in a 65 line screen and these shops typically have and use 10-14 colors excluding flashes and cool downs. A few shops have more colors than that available if needed. These higher color auto's make use of extra "shades" of color often used to beef up the print saturation. With so many colors going down for sim process, what is a thin coverage is often intended and built into the separation process. For the average good shop, I often provide seps containing 4% dots in a given area x 3,4 or 5 colors to create a shade.

Lastly, I do believe that those small dots (while confined to a pattern) in traditional halftone can produce hit or miss areas, when using the typical 305 on a 65 line screen, but out of 10-14 colors, much of that is hidden anyways. If using the higher mesh (on a 65 line screen), you can hold more of the smaller dots.  So the key for holding those smaller dots...is using that finer mesh higher than the tried and true 300 mesh range.

In addition, the (as was mentioned earlier in another thread), DTG spits out (like you have said), 7-10-15 Picoliters of dot sprays. (THAT) can be seen on the shirts and when combined x 7 other colors/shades, produce a full fledged detailed vibrant print.  So, (these small dots) can be seen, can work and are worth trying to achieve. We will not get (that small of a dot) as seen in a 7 picoliter spray, held in even the finest mesh, but if you do use a mesh that works correctly (with the right sized small dot) they can be held in print. Of course, this is not for everyone, but it can be done. There are customer target audiences who do desire this level and there are people putting it out there. Again, I agree.  95% of the shops don't need to do this or even try, but I do believe that they should be aware of what is possible and what some shops can do.

That said, I do know that, the contribution you provided is indeed true, accurate and 100% right for most all shops. It's invaluable and a gold mine of info.

Thanks for chiming in on the conversations and contributing your obvious vast experience. I know I can sound like I disagree and I really don't. I simply think there is more than that.  I respect you and the info and would encourage you to continue to let this good food (info) flow as I know all of us do.

P.S.  I am aware that I could be wrong on some things and welcome the opportunity to be proven wrong. After all, it's the "correct" info that is the goal. Not the goal to be right.

Thanks
Dan





Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: ABuffington on March 18, 2014, 01:48:49 PM
Hello Everyone,

Yes Dan you bring up a good point about base plates.  They don't have to be white, or opaque.  Sometimes it can take 2 baseplates of differing colors to pull off a design.  Subtle tone on tone printing works better without a super bright white base plate.  We had a client years back that was into vintage rock n roll t-shirts.  They wanted to mimic old worn t's with missing ink and faded colors.  We used a clear base plate for their work.  It gave a vintage soft look to the print making the ink slightly transparent and 'worn'.  Add some stretch additive to the clear base for super soft prints.

On the subject of dots we haven't mentioned stochastic or index printing.  The one area I like to use these dots instead of halftones (or you can combine with halftones) is in a design like a band where the size of the faces is small, or where I have a small area in the print like chrome details of a guitar that are quite small.

A fast method for separation is to take a duplicate file>put art on black background>greyscale>level adjust for image punch>Invert>output in a 55 line halftone.  Then for the color plates take the original art>Mode>Index>choose 2-4 colors more than the press can hold since index will choose the shirt color, clear, and duplicate some colors. With both the original master file open and the index file open you can double click on a color in the color table for the index colors to open up the color picker.  Then take the eyedropper over to the original color file and pick out the primaries, secondaries and get the color table for index to match closer to the original.  I never understood why index mode shifts the color table to darker duller colors.  To be able to know how to combine dots to form secondary colors is not too difficult, but to combine multiple colors is a skill, even harder IMO for halftones, takes lots of practice.  We would clean up stray dots that didn't belong.  Like a erasing blue index dot lightly scattered across a yellow gold to clean up the image.

Separation skills are really an art unto themselves.  It is a never ending quest.  Channels, Masks, offer so many options in combining colors that it is a wonder the job is ever done on time or on budget!  There are some clunky auto sep programs available that can make ok seps, and they do a nice job, but to really capture details and smooth color transitions and predictable prints takes skills. 

Screens: 150S, 180S, or 225S for the baseplate - 350-380T for the over prints.  Mesh callouts for the index method above.

Al
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on March 21, 2014, 07:55:18 AM
These types of discussions are the brain food for people in this industry.
I love this discussion.  I have used index and stochastic on this level and overall, I prefer the stochastic for the blend ability compared to the side by side dots of index printing. Also, as you've mentioned, multiple colors work best.

I'd love to hear more later.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: dahmitdesigns on March 28, 2018, 08:12:37 AM
We run our bases on 173.
Title: Re: Halftone file for DIY films/screen testing and some pointers on calibration
Post by: Dottonedan on March 28, 2018, 02:19:17 PM
That should be printed at about 35lpi then.   You can go a little higher, such as 45, but don't expect to hold saoft fades out to the shirt color with any smoothness. It will drop off. The mesh threads are actually blocking the smaller dots at that point.