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screen printing => Screen Making => Topic started by: blue moon on September 15, 2015, 10:55:40 AM
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'just took a reading from a non linearized (un-calibrated) RIP. These are pretty much par for the course as I see them several times per year and they pretty much all have very similar numbers. Note that the 1% dot actually comes out as a 5%. This just goes to show that when somebody says they are holding a 1% dot they really are not. They are holding a 5% dot in case like this. Physical limitation of the 305 standard mesh is calibrated 3% (from what I've been told and what our experience backs up).
1 5%
2 7%
3 9%
5 13%
7 16%
9 19%
10 20%
20 35%
30 50%
40 63%
50 72%
60 84%
70 93%
80 98%
90 100%
Go print the test file on top of this section and if your halftones are closing in before 99% your RIP is off. . .
pierre
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Agreed
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Looks about right from my experience here too.
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Good observation there, Pierre.
Steve
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For those using Accurip..
the ability to adjust your tonal curve was removed in the last update.. when asked, they said you don't need it.
this just proves how wrong they are.
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There is also the dot gain that occurs during print which is just about the same. One of the other issues with inkjet imagery below 10% is that older heads can scatter the pico liter dots which are quite transparent and prevent imaging on the screen. True Film with a solid circle/ellipse halftone below 10% is far easier to image, up until the dot size is less than mesh thread diameter. At that point halftones get blocked out anyway. I have a client trying to image 180lpi halftones. This is mathematically impossible in lower percentages. Even pushing 133 has severe limitations on lower percentage values.
180 lpi is 1/180lpi = .0055 inches for a 100% dot.
.0055= 139 microns so a 5% dot would be 6.95 microns. (.05 x 139), a 10% halftone: 13.90, 20% 27.80 microns. The smallest thread we make is 27 and 30 microns in diameter which will block some of the dots no matter what angle is used.
Has anyone out there used Wasatch's hybrid option of halftones that transition to stochaistic below a 15 to 20% tonal value? Curious if it prints the transition smoothly and fades well into the shirt.
Al
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The Accurip linearization never worked anyhow, for what it's worth. I learned to clip dots off and pull back channels to accommodate. Looking to change this soon by using a better RIP (been "working" on this forever it seems) so we at least know our high/low % that can be held on various meshes.
Also curious about wasatch's stochastic. It adds up to me on paper and seems like a no brainer for one of the screens in a 4CP run but I wonder how easy it is to actually implement day to day as well.
Alan, using your math and smallest thread rule, the lowest %age dot one could consistently hold @ 55lpi on a 350/30 or 330/30 or 310/30 mesh would be 7% but I'm guessing open area comes into play here as well?
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I ditched Accurip long ago after I was told that I did not have to linearize by the owner of it and have been with Wasatch ever since. I will have to see if my version will allow me to print stochastic dots at a certain percentage. I am pretty sure that is only available in the next level above what we have. The only times we run into any issues are around the 4-7% linearized dots. Most of the time though we are killing the 3-5% dots off anyways so not too many problems arise. We do a lot of halftones at 55 lpi as that is our go to with water base and most plastisol.
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The Accurip linearization never worked anyhow, for what it's worth.
It worked perfectly fine for me when I linearized my R1800 and then the 4800.
Once I dialed in my curve, I was able to hold and print a 3% dot on my 280 mesh.
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Pierre,
Just curious if you are measuring the films or the actual print? If measuring the actual print what is the standard benchmark? I know even a two week old squeegee will print differently than a new one and a harder squeegee different again. Or even a different screen for that matter.
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The lowest percentage math I gave would require all the dots to land completely on the thread so they couldn't print. It only takes part of the halftone to be over open area to print. So at a good angle it is possible to image in the 4% range with a high enough mesh count. Also dot shape comes in to play here. Ellipse dots can span the thread and hit the open area more often than other dot shapes. Regardless, I have seen round dots curved to print 10-90 with prints that are incredible as well as pushing the envelop to capture the lowest percentage possible. Capturing the highest percentage possible and printing it well is often harder and may impart more tonal quality than being able to print the low percentages. The tonal fade of over print to dark fabric is often the wow factor in sim process and can be dependent on how well the base plate captures the finer halftones than the high mesh overprint colors. Sim process has so many other factors as well that contribute to the overall quality of print that the recipe for one printer may be different for another. Subjective viewing at typical viewing distances often hides what we think is needed when viewed with a loupe or microscopoe. From pre-press curves to the type of film/imaging solution there is a world of difference in what is printed from one printer to another. We view Wastatch as a great solution to controlling linearization, plus this transition to stochastic is something to play with and I would see it as a good method to print a gradation that faded out into the shirt to avoid vignette moire and get the fade into black fabric smoother with no moire developing from a low halftone percentage. I'm testing a new emulsion today with 0-100% tonal ramps and I'll see how this halftone to stochaistic looks on screen.
We received a Starlight for testing today, thanks Mr. Hoffman, so I will test an inkjet output and see what a 300/34 and 330/30 can hold percentage wise.
Al
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Al~
What output device are you using?
Thx
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jsheridan- I think I had a thread on this long ago. I can't remember all the issues but after working with Charlie, who always provided great AR support, it just wasn't happening. We were losing data on output v. linearizing the output and I did troubleshoot the heck out of it but never resolved. 4800 as well.
Abuffington- thanks for that, I had the same thoughts on halftone shape/angle. I like nerding out on this even though you're correct that the finished print viewed at normal distance is the real test, not so much the technical details we tend to focus on. Let us know what you find on your Starlight resolution v. MH testing! We still have our MH still setup to test this but haven't been able to for lack of time. For textiles up to 60lpi the Starlight has easily been "good enough" for us.
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For those using Accurip..
the ability to adjust your tonal curve was removed in the last update.. when asked, they said you don't need it.
this just proves how wrong they are.
Well, that's just not right. Thanks, I'll have to remember to not upgrade...
Steve
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Gary, we have an older 9800 with Wasatch RIP that doesn't have a lot of mileage on it. The Epson is mostly for testing and custom screens. Inkjet in any form simply doesn't compare to real film for dot quality. I will agree with john that it is possible to lose data with linearizations. But linearization can be repeated after the initial linearization. I have linearized the Epson printer, output the tonal ramp again, linearized again. It did correct some of the tonal values that lost dots, or were below the densitometer reading. In Wasatch you do have 2 calibration curves as well. Press Curves and Calibration curves that can still be tweaked similarly to how we do it in Photoshop. this helps fine tune quarter tone values and can help open up the 60-95 range better. It takes all of 20 minutes to print, read and enter the values from a densitometer and improves print quality but then it goes on press and a ton of variables there often mess with good intentions.
Al
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For those using Accurip..
the ability to adjust your tonal curve was removed in the last update.. when asked, they said you don't need it.
this just proves how wrong they are.
Well, that's just not right. Thanks, I'll have to remember to not upgrade...
Steve
Thanks for the info.
When I get print error, I have to turn off the Dot Gain Control in setup. After printing a job, I turn it back on.
I think they just don't want to admit they could not fix a bug in the software.
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Abuffington- thanks for that, I had the same thoughts on halftone shape/angle. I like nerding out on this even though you're correct that the finished print viewed at normal distance is the real test, not so much the technical details we tend to focus on. Let us know what you find on your Starlight resolution v. MH testing! We still have our MH still setup to test this but haven't been able to for lack of time. For textiles up to 60lpi the Starlight has easily been "good enough" for us.
We often refer back to the idea that there is a standard or "typical" viewing distance to judge a print) and that usually falls back to a purchasing decision distance or (in a store) when you walk by and say, that looks good. This is said to be the 3 seconds at 3' rule. These numbers change, depending on who you talk to. Some call it the 5 second and 5' rule and 5 seconds at 7' LOL.
What I think is more important is to mention the print approval distance is different than the store purchase distance. A print savvy customer will view the shirt much closer, (12" to 24" away) when they pic it up and judge your print. So print detail (for you) is more important than the varying store purchasing distance.
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Abuffington- thanks for that, I had the same thoughts on halftone shape/angle. I like nerding out on this even though you're correct that the finished print viewed at normal distance is the real test, not so much the technical details we tend to focus on. Let us know what you find on your Starlight resolution v. MH testing! We still have our MH still setup to test this but haven't been able to for lack of time. For textiles up to 60lpi the Starlight has easily been "good enough" for us.
We often refer back to the idea that there is a standard or "typical" viewing distance to judge a print) and that usually falls back to a purchasing decision distance or (in a store) when you walk by and say, that looks good. This is said to be the 3 seconds at 3' rule. These numbers change, depending on who you talk to. Some call it the 5 second and 5' rule and 5 seconds at 7' LOL.
What I think is more important is to mention the print approval distance is different than the store purchase distance. A print savvy customer will view the shirt much closer, (12" to 24" away) when they pic it up and judge your print. So print detail (for you) is more important than the varying store purchasing distance.
An excellent point. It's really about the end user. We print primarily for retail sales with much of it online but a good chunk going onto racks in brick and mortar stores and each market has it's own requirements for sure.
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I also forgot to say thanks to Pierre for this post. I'm saving those numbers in a doc for a very loose example/reference to use when training others here on pre press of where their output on the film will be compared to the PS channels when using a non-linearized inkjet to film.
Sadly, we don't linearize with AR as it resulted in data loss and simply didn't work for us and instead will adjust values in seps to accommodate. I know where we're at with gain pretty well but it's all stored "up top". It works for us but when you take the head containing that information out of pre-press it's not going to work anymore and we of course will be investing in a better RIP very soon. Saying this because I know we aren't the only ones out there who work this way and still produce good, consistent prints.
This one is much more variable but a general gain example onto a printed garment, both coe cotton and ringspun would be verrrrry interesting to have as a loose reference but not sure how you can obtain that data.
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The bottom example is why I will suggest using the method of dividing your mesh by 5 to give you the line screen halftone you should be near (to hold the most amount) of the smallest detail halftones. (e.g 305 mesh divided by 5 = 60 lpi MAXIMUM rounded). If you were to use the 4 or 4.5 that most people use, it gives you an even higher lpi, making it all that much harder to get the smaller dots. 305 divided by 4 = 76.25 (rounded) = 75 lpi. To me, on a tee shirt, a 60 lpi versus a 75 lpi is not that big of a visual benefit, but I can hold all of my information printed onto the tee at 60lpi much easier.
To add to that, I make it even easier and prefer 50 on 305 and sometimes just 45lpi. People say, well, I don't want to try and hold the 1% dots anyhow...but I say, you can get closer. For most of us, we can't hold the 5% let alone the 1% so your position is, Blah! Never gonna happen.
Pierre's stance is that the mesh diameter and open area of a 305 does not enable you physically to hold a 1% dot. Obviously, he's right...and he's wrong. It's all in how you look at it. I say yes, it does...if you are printing a lpi that works to hold that 1% such as a 50lpi on a 305. The higher the lpi, the less chance you have, but you can get closer. Why not hold as much information in the art that you can? After all, it's about reproducing the image accurately, it's not about holding a specific lpi on a specific mesh.
Why use such a high lpi like 60-75lpi that it reduces your ability to hold fine detail information?
When you look at the actual size of a linerized 1% dot in a 50lpi, as a guess, it is going to be somewhere near the size of a 5% dot in a 65lpi. You all can hold a 5% dot much easier in a 65lpi right. Some yes, some no, but for the most part (it's easier). So, why would you think you have no chance at holding a 1% dot....in lower lpi?
Why do you want to? because there is art image information there. Sure, it's not always needed. Note very job requires you hold down to 5-3% dots. Some jobs have halftones in it that only go down as low as 20% tone. This then, is another example of the fact that you need to focus more on holding a certain SIZE and not a certain LPI. You see, you can actually hold all of the dots in some jobs at 55lpi (on a 110 mesh). Wow's that? Because the size of the 20% dot in a 55lpi may be very similar to or equivalent to the size of your 1% dot in a 25lpi.
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Add on,
You are seeing some people say they print 70-90lpi on very low or common mesh like 65lpi on a 230 or 90lpi on a 250 etc. Those people are looking at SIZE of dots. Not focusing on staying within the traditional expected LPI on a specific mesh. They look at the 90lpi and compare to the mesh thread, then determine (at what % can I go down to? What LPI is going to give me awesome mifddle tone image resolution? So some determine it might be 90lpi and still hold that dot on this mesh.
So lets say in a 90pi, (on a 250 mesh), they see that they can hold the 25% dot well and nothing less. Then, then look at their shadow tones and see that they should be somewhere in the same area (70% tone) that will still hold a dot with some gain. NOW, they just don't use the same art that came out of photoshop or a sep program. They have to tweak beyond what most have ever seen or imagined. Dodge, burn, levels, curves, selections with additional fills, additional cut backs, heavier underbases, lighter top colors, adding colors where color is not, etc. all to get a great print with this scenario.
It's all about the size. "Size does matter". These people pushing the limits are not looking at trying to hold the 1% in a 75lpi nor the 1% in a 50lpi. The commonality between these examples is that they are focusing on printable SIZE and not LPI.
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Getting back to this after some time off. Great stuff Dan and good advice, however for me the art and customer determines the lpi I would need. Lots of small elements with tonal change? Higher LPI. The need to print a detailed guitar?, about all I print anymore, and get the wood grain perfect, higher LPI again. I have seen 60lpi with good curves to eliminate anything below 5% on 135S that exceeded the quality of a 65 line:
(http://murakamiscreen.com/wp-content/uploads/2012/10/Home-Field-Advantage.jpg)
As well as 85 line to capture stunning detail in a guitar(http://murakamiscreen.com/wp-content/uploads/2013/09/Team-Mucom-Rocks-Bobs-guitar.gif) printed with 225S baseplate and 350S on the colors.
All depends on the customer and subject matter. I have discovered that Wasatch will break off halftones and print stochaistic below X% that pretty much fixes the moire with 2-20% dots. The hybrid screen is accessible through Wasatch Precision Rosette and clicking on halftone properties. There you can set the micron size of the dot and also control the % it changes at.
Al
Alan
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Pierre,
Please email me your test file.
mdhlexp@aol.com
Mark