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tpitman · October 20th, 2007

Quote:

Originally Posted by ImageIt


	I'm currently in the process of perfecting my ability to print process color. So far things have been going well. It has taken at least 6 sets of 5 screens to get me to where i'm at now and expect to go though more screens in the future. I'm glad to share whatever knowledge i have. fred

These samples are process on black tees? Not to sound skeptical, because all I've printed is process on white with a white underbase to help hold down fibrillation, but many say process on black is tough or next to impossible because the white underbase necessary to block out the black renders the process inks pastel. I'm using Union's process inks also. Is the transfer function you show here the one you used for this prints? I already have to double-stroke some stuff to get a good, rich print, so maybe I'll try these, since they're a little more aggressive on the ends. By the way, the samples you are showing look pretty damn good, especially for someone just venturing into process work. Process on black would be a hell of a lot easier than simulated on black if it works as well as these samples indicate.

Thanks for your input.

ImageIt · October 20th, 2007

Quote:

Originally Posted by Solmu


	That simply doesn't make any sense. If you qualify for an academic copy you should buy it whether you can afford the full version or not (why not save the money?), and if you don't qualify for an academic copy, you shouldn't buy it, as you wouldn't have a legal copy of the software. Paying money to break the law is just twice stupid.

There is nothing "illegal" about academic software. In order to purchase it, it must be purchased with a valid school ID. College, high school, middle school... it doesn't matter. Anyone with a student ID is legal to purchase the software. Once purchased, no limit exists on how the software can be used nor any prohibition on commercial usage.

For an individual new to photoshop, an academic copy is there to tempt this individual to purchase and learn by offering a discount price.
Once an individual has learned photoshop and has grown a successful business which requires multiple copies of photoshop, full commercial packages should be purchased.

I'd suggest anyone who has never used photoshop to sign up for classes and use their own student ID!

fred

Solmu · October 20th, 2007

Quote:

Originally Posted by ImageIt


	There is nothing "illegal" about academic software.

If it's purchased lawfully (i.e. not obtained by deception) by a qualified user; it can't be bought and used by just anyone as you seem to be implying.

ImageIt · October 20th, 2007

Quote:

Originally Posted by tpitman


	These samples are process on black tees?

Yes, 100% cotton black Jerzees t-shirts.

Quote:

Originally Posted by tpitman


	Not to sound skeptical, because all I've printed is process on white with a white underbase to help hold down fibrillation, but many say process on black is tough or next to impossible because the white underbase necessary to block out the black renders the process inks pastel. I'm using Union's process inks also.

The white underbase must be very good, but it isn't really any different than trying to print a good white onto black. Last week we tested several different whites and switched to cotton white.

For black i don't use unions process black, but have typically used a high opacity spot black and print the black first. I'm also testing unions triple pigment process black. I've also posted details on what i call "super black", which is where is flood the other process color channels to 100% whenever the black channel is at 100%

Quote:

Originally Posted by tpitman


	Is the transfer function you show here the one you used for this prints? I already have to double-stroke some stuff to get a good, rich print, so maybe I'll try these, since they're a little more aggressive on the ends.

Yes, that is my transfer function. In separate post i describe a calibrated double stroke. With a single stroke i was getting a lot of snowflaking, so i adjusted the transfer function back about 40% and always double stroke the screen. The light end of the transfer curve is bumped up to where the screen can actually produce a dot. The dark end makes a rapid jump to 100% coverage over 90% because i want full coverage to be as full as possible. Where the art has 95%-100% coverage, the double squeegee will put nearly 150% ink.

By using a calibrated double stroke, the shirt to shirt repeatability is very good.

Quote:

Originally Posted by tpitman


	By the way, the samples you are showing look pretty damn good, especially for someone just venturing into process work. Process on black would be a hell of a lot easier than simulated on black if it works as well as these samples indicate.

I'm new to screen printing, but not new to printing. I'm glad my experience is transferring so well. The transfer function i posted would be nearly identical for a chemically etched gravure cylinder, except gravure uses a cross hatch spot function.

For jobs designed using full color, printing them is process color should be very easy. I've got a 6 color press, so simulated process really isn't an option for most designs.

Next week i'm planning to make a banded color test and tune the transfer function.

fred

ImageIt · October 20th, 2007

Quote:

Originally Posted by Solmu


	If it's purchased lawfully (i.e. not obtained by deception) by a qualified user; it can't be bought and used by just anyone as you seem to be implying.

The software companies lost the case which restricted the resale of software by the person who purchased it. If a person lawfully buy a copy of software, the software company can not prevent the private resale of the purchaser.

For example, if i choose to sell my business, i will sell it including the software. If my business goes bankrupt, the software could be sold to the highest bidder.

fred

ImageIt · October 20th, 2007

Quote:

Originally Posted by rrc62


	Would I still need the white underbase? How would an average photo look after pressing with no white underbase? My guess is that the white makes the colors pop.

Process colors are transparent colors, so they need to be printed over white. This either means a white shirt of a white base.

fred

rrc62 · October 22nd, 2007

I see. I think your idea about printing the underbase last using pin registration would work fine. I see the need for micro registration printing the 4 colors, but the underbase could be off a whisker and not really effect the print, meaning registration would not be that critical. Since these are transfers, the underbase would in fact be the last printed layer.

ImageIt · October 22nd, 2007

Quote:

Originally Posted by rrc62


	but the underbase could be off a whisker and not really effect the print, meaning registration would not be that critical.

This is why the white needs to be slightly choked to allow the process colors to trap over the white.

With a pin registration system, there would be no difference between registering the first 4 colors with the next 4 color and the next 4 colors. As long as you leave up 1 screen at screen change. the job can be registered using the one screen still in register to the new screens which need to be registered simply my unmasking the crop marks and printing them on a sample to register the next. Of course samples could be printed and the registered plate removed to allow a 4 color change.

Each transfer will be keyed to the platen it was first printed on. If you want to print 10 rounds of printing, each transfer would need to be marked as to which platen it was first printed, then re-printed on the same platen. This way platen registration would not effect final output.

I'm still new to screen printing, so my skills are still rather low. Even so, i've not had any real issues with registration. Due to my laser output, the crop marks do not always match up on all 4 corners, but i try to register the top 2 exactly, while still making the best compromise at the other side. Because i'm only printing a 55 LPI screen, the width of a crop mark is much thinner than the width of a halftone cell. What is key is how much trap there is between the process color and the white.

fred

Ken Styles · October 23rd, 2007

Wow, this thread is jam packed with great info.
I think I'm gonna bookmark it.

rrc62 · October 23rd, 2007

I need to think about this in reverse, since I'll be printing transfers. If I understand correctly, the process colors should overlap the white slightly so no white is seen around the edges. In my case, since I'm printing the white last, I would choke the white slightly so it falls inside the outline of the process colors. Am I on the right track?

ImageIt · October 23rd, 2007

The white needs to be the last thing printed on the transfer, so that when it is flipped, it will be the lowest level on the shirt. The white should be printed on the transfer smaller than the process colors such that a halo of process color could be visible around the edges of the white.

Not to confuse you, but the white could also be printed 1/16 or 1/8" larger than the process color, so that no color would be visible around the white. This would result in a white halo around the image. If the artwork depends on the outline of the art being black and you also want to place the art on a black shirt, the white needs to be spread.

The bird image has the white spread to form a halo. The Dali Lama has the white choked slightly to keep it under the process colors.

fred

rrc62 · October 23rd, 2007

Thanks Fred...I'm waiting on supplies to give this a try. Is there any particular order that the color layers should be layed down?

ImageIt · October 23rd, 2007

Quote:

Originally Posted by rrc62


	Thanks Fred...I'm waiting on supplies to give this a try. Is there any particular order that the color layers should be layed down?

Since i like to use a pigment black instead of the process black, my black must be the one next to the white. Other than that, I don't have any firm rules.

What are you using for transfer paper?

fred

rrc62 · October 23rd, 2007

I ordered this paper...

Transal Premium HOT PEEL Heat Transfer Paper 15x15"

I also just noticed "adhesion powder" on their website. I wonder if that is required or just an additive to make it better. It says to apply it to the last layer then do a final cure. I was under the impression that when printing to transfers, you you cured just enough so it is dry to the touch, then final cure takes place under the heat press.

I'll probably also use pigment black since I already have it, so my black would be the last layer before the white. C,M,Y,K then White.

rrc62 · October 23rd, 2007

What would you guys recommend for angle and dot shape for the CMYK layers. Working with each channel in PS worked, but I think I get a better quality halftone in X3 then printing in Ghostscript. I used an output resolution of 800dpi and the "halftone screen" method. I may not be using the proper angles, shape and lpi settings.

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