screen printing > Separations

Why 600ppi instead of 300?

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Dottonedan:
People have read about my use of 600ppi for files and a few members here are also using 600 as well.  Below, sort of explains why this higher resolution works for these specific types of files for screen print more so than 300. Especially when needing to choke an underbase or very thin line work.

The 300 letter T doesn’t really show the benefits in this example. By the time I had to resample down to 72ppi, for uploading here, it doesn’t show how thin the top serifs are. This would be all that much harder to burn and hold in the screen. Often it is broken up, not exposing the thin lines at top. Even more so with smaller type. This type is done at about .5” tall.

The 72ppi is not something that any of us would ever use for screen printing (I don’t think), but sometimes some people might try to use what was given to them without adding more "art rebuild time” and can look horrible on press. But it makes for a good example of one extreme to the other.

For screen printing, the only real benefit of higher than 600ppi like 1200, is that it would help to create the smaller dots (1-10% dots) to look more round versus pixels. But the reality is, that you can’t tell at that range, by the naked eye, if it’s a nice round 3% dot or if it’s a 3 pixel shape.
Once printed with wet ink, smashed onto a tee shirt, another 1-5 screens smashed over top of that, it’s hard to know if that was a nice round dot, or a 3 pixel shape. Therefore, I don’t see much more benefit coming from a 1200dpi printer than a 600dpi printer.

Now Laser to screen. That, is a whole other beast...and does make perfectly round small dots (or as near as you can get). The SATTI laser has an option to do an equivalent to 2540 dpi.  What this does...for me, (since I said that anything over 1200 is not really that beneficial in the end result) is that the Laser, with that ability, would enable you to do exceptionally high lpi such as 85-100 lpi and maintain the desired tonal range you are looking for across the board. With 1200 and 600, it’s a bit harder and you have to fake it.

ZooCity:
Sing it brother.

600ppi/dpi is the min. for quality screen printing work imho and should be the starting point, the baseline.   

How are things going along with the Saati laser?  (don't mean to derail)

Dottonedan:

--- Quote from: ZooCity on November 23, 2020, 07:18:56 PM ---Sing it brother.

600ppi/dpi is the min. for quality screen printing work imho and should be the starting point, the baseline.   

How are things going along with the Saati laser?  (don't mean to derail)

--- End quote ---

Funny you should ask. I just had a conversation with Ben Petsy today.

I’ve read that the LED Lasers last over 10,000 hours with 100% efficiency. That’s roughly 5 years. It’s advertised that there are no consumables with Laser, as there is no INK or WAX to be used. LED laser light does ware out after time. A Wet ink print head, can last 3-6 years on average. I’m not sure what a Wax print head will do these days but it’s better than it used to be in older models due to excessive heat on the heads over along period of time. I think that could be said to last near or as well as the wet ink. So print heads last 3-6 years “typically”. and Laser lights last 5 years. How much is it to replace all laser lights. If you do one, should you also do all of them since they will eventually all go out some time soon at that point?  Did I misrepresent anything?

Ben replied:
"at any given time there are roughly 60-75 of the lasers that are actually in use depending on which unit you choose and the size of the image. That said, and out of say 96 lasers (with the 6080 horizontal) you have roughly 20 lasers as “spares” before you actually have to purchase a laser, which costs about $200 each. It isn’t necessary to replace the entire array when one burns out."

It comes with a 2 Yr warranty.  I don't want anyone to think that the answer, was a ding against the SAATI LTS in any manor.

The reason being, that this LASER REPLACEMENT expense alone, is about the same as you would have with WAX or WET ink consumables in the long run. Then the print head cost is another factor that you will eventually have to work in there also. So the total cost of (if you did) replace all of the lasers, it would not be anything more than you would over time with the other options.

Wet ink cost per Ltr. $177.00 x 1 Ltr every 2 Months (guess). x 12 = $1062 Pr Year. x 5 Yrs = $5310.00  (consumption changes per shop). Could be half that over 5 years or could be double for some.

Cost Pr M&R Wet ink heads should be in the area of $1300 per print head. Not sure what the WAX print heads cost. Anyone? So for the I-Image S, you only have 1 print head to worry about while the other models can have as many as 3.

I just googled and the Kiwo XTS Wax, 1kgPrice: $354.00. Again, I don't know what you get out of that...but I had seen posted a couple times that the cost of Print heads and cost of wax were pretty close between Wax and Wet ink with wet ink just a tad less.

Actual usage and expenses for each shop will be different than others.Now, ONE more thing about the SAATI.  With that LASER, and those TOP level screens you can get from them, They are (to me personally), the BEST so far. This is a result past any 600 or 1200 DPI wax or wet ink machine. I just don't see yet, how anything can compare.

Dmax?  Nailed it. No issue obviously.

Dot shape? Nailed it.
Exposure time? Nailed it (while imaging).
For dot gain control (as it pertains to all of the other factors for dot gain), that is something that needs looked into more carefully. I think I heard some mention from SAATI representatives at some point that they were looking into options, but as far as I remember, there were no quick or easy methods to adjust at output. All gain compensation would rely on the separator providing the file to the machine for the gain control. That means your artist need to be able to do that well in the art. They can, and should, but not every production artist does that well.
Total imaging and exposure time? Iffy for a single imager, but having it print two screens at the same time, Well now, that's another story and to my mind, now puts that in the running with the more economical machines.
Laser certainly is something to really consider hard. Don't just pass it by on price alone. The price is worth it to you.

inkman996:
I am not a fan of using an arbitrary number such as years for guesstimating the life of a print head. Years does not mean anything if one shop barely uses the machine or another shop uses it 8 hours straight every day. Just like in commercial equipment they use hours not miles or years, the hours are based on actually running time, excluding the time the machine is not running. I would prefer to see a counter system that counts the actual amount of time the print head itself is firing, that would give a far more accurate life expectancy to then be able to better compare the life of a print head from one shop to the next.

A salesman could easily tell a potential customer that he knows of one shop that got 7 years out of his print head but neglect to tell you that shop used the machine a couple times a week. What he will not tell you is that another shop he knows that uses the machine 8 hours a day only gets one year out of each print head.

GraphicDisorder:
Knock on wood, our i-Image is still on its original print head. 2014 Model.

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