Author Topic: Halftone Printing  (Read 261 times)

Offline scottyjr

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Halftone Printing
« on: February 11, 2010, 06:29:31 AM »
Something I've always wondered about, having an idea about the correct way to do it, is printing halftones over a white halftone base. This seems very difficult to accomplish because, in my mind, the extremely small halftone dots of the top color must sit precisely on top of the underbase halftone dots. I can imagine attaining very good registration but underbasing a halftone leaves no room for any misregistration; no peeking allowed. The same concept has always made me wonder about how four color process being precisely lined up? Am I missing soemthing?

Not only something that must be accomplished with an underbases but also with a blend. This is I suppose what my problem is here. The first picture is what I wanted the print to look like. It was accomplished by printing an 80% underbase of white, highlight white, blue and red last. What I wanted to do was to print the underbasse, then blue, then red and the highlight white last to make sure the outlines were top dog (smell a trap?). The second picture is what I got when I did it that way. I think what happened was that a good percentage of the halftone dots ended up being printed on top of the blue and red dots and not where there was no red or blue ink like it should have. The scan I took (3rd picture) seems to confirm that.

Is it all a matter of registraion? Or do all things that I can think of that matter, very tight screens, perfect positives, tight press, and perfect registration all be requirements for any precision printing. Did I just answer my own question? I think I did. Precision printing requires precision. But then again, it's hard for me to imagine that all the successful halftone prints out there are only done by printers that use those requirements. So do the others use some kind of work around? That's my plan. I 'm gonna use a fifth screen with just the outlines on it. I'll get the results I want but probably not the proper way.

- Scotty







Online Homer

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Re: Halftone Printing
« Reply #1 on: February 11, 2010, 07:19:53 AM »
from the close up view, it looks like you used some sort of separation software? - you are doing this with 5 screens? insert holy shit whistling sound here - what are you printing on, a <g> . . ? haha . . looks furry...
 In my opinion, this isn't a design to use a halftone base. We usually do that on larger fill images, I'm sure it can be done here, but it's a small area of coverage. .

Offline mk162

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Re: Halftone Printing
« Reply #2 on: February 11, 2010, 07:34:28 AM »
Homer, it's called a pellon, or test square. :>i

I agree with Homer, I would have printed it the way you did the top one. Also, you should choke your base bask if you want to print halftones on halftones. Or, if you have problems lining that up, just do each as a spot color and print flash print each color on top of itself with high opacity inks. It doesn't solve your problem of not lining dots up, but it will make it easier in a pinch on a short run.

Your underbase looks larger than your overprint.

Offline Ripcord

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Re: Halftone Printing
« Reply #3 on: February 11, 2010, 09:13:23 AM »
The problem I've had when I try and do a graduated halftone underbase is that it gives the print a grainy look, due to the coarse dot pattern (I normally use 30 lpi for the underbase and 42 lpi for the color, with 156 and 230 screens)

I do sometimes use a solid underbase but give it a uniform dot pattern of about 60-70%, which causes it to appear on the shirt as a solid print but lays down less ink for a softer hand. Often I'll use a combination- solid white for the white areas of the design and dark halftone for the areas to be overprinted.

One thing I'd like to try but haven't yet is to do a solid underbase, but tone curve it so the shadow areas don't print (invert the positive), then a second underbase with a 230 screen and 42 lpi halftone, angled to prevent a moire, to give it that feathered look...then the color halftone on top. It's an extra screen, but I'll bet you can get some nice effects that way...

Offline Duke of York

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Re: Halftone Printing
« Reply #4 on: February 11, 2010, 10:15:58 AM »
I'd have print it using a solid white underbase and process color using 55LPI with traditional angles and an elliptical dot.

The would i use to describe what is happening in the image is "strobing", this is where the registration of the press either aligns or doesn't align to other halftone dots. Traditional screens counteract this issue by the rossette being a controlled point of moire. Shift the screens around and the moire will shift with it, rather than strobing.

fred


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Re: Halftone Printing
« Reply #5 on: February 11, 2010, 10:20:48 AM »
fred - why would you do this in process? you would need 4 screens vs 3? just curious. . .my 1st guess is that's the only ink you have haha. .

Offline screenxpress

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Re: Halftone Printing
« Reply #6 on: February 11, 2010, 10:38:02 AM »
Looks to me like you used the same screen (or film) for the highlight white that you did for the underbase. True?

If so, that, of course, won't work. If you're really going to use a highlight white, it has to be just for the areas to pop.

I still get good results by doing a P/F/P/F on the underbase white and wet on wet from there. No Highlight white.

Is the white supposed to show as an outline? If not, need to choke it back so the color lays just outside the white where the overlap splash will not show near as much as white does.

Just my 2c.
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Offline Duke of York

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Re: Halftone Printing
« Reply #7 on: February 11, 2010, 10:51:54 AM »
fred - why would you do this in process? you would need 4 screens vs 3? just curious. . .my 1st guess is that's the only ink you have haha. .


You sir, are CORRECT!

Logos use specific hues of color, which typically the nearest blue and the nearest red, just aren't close enough. An ink mixing system could handle this, but i don't have one. The nearest ink store is a 2 hour round trip.

3 screens verses 5 screens is just simpler and quicker than dealing with special order ink.

fred

Offline mk162

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Re: Halftone Printing
« Reply #8 on: February 11, 2010, 10:57:33 AM »
That is why I have damn near every color of wilflex ink. Most logos use the same colors, most reds are either national or dallas scarlet. Most navys are bears or regular navy.

The problem with process is if you have to reprint a color that ran out of ink or somehow didn't print right, you end up with a funky shade.

This is a spot job all the way.

Do ink shops not ship to Dahlonega?

Offline scottyjr

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Re: Halftone Printing
« Reply #9 on: February 11, 2010, 11:19:56 AM »
from the close up view, it looks like you used some sort of separation software? - you are doing this with 5 screens? insert holy shit whistling sound here - what are you printing on, a <g> . . ? haha . . looks furry...
 In my opinion, this isn't a design to use a halftone base. We usually do that on larger fill images, I'm sure it can be done here, but it's a small area of coverage. .


Nope, didin't use any separation software. Draw separated it.
Well, it would have to be at least 4 screens using an underbase to get bright colors. The 5th screen is a means to get what I couldn't accomplish with4 screens.
This was printed on a pellon.

Offline scottyjr

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Re: Halftone Printing
« Reply #10 on: February 11, 2010, 04:08:59 PM »
Looks to me like you used the same screen (or film) for the highlight white that you did for the underbase. True?

If so, that, of course, won't work. If you're really going to use a highlight white, it has to be just for the areas to pop.

I still get good results by doing a P/F/P/F on the underbase white and wet on wet from there. No Highlight white.

Is the white supposed to show as an outline? If not, need to choke it back so the color lays just outside the white where the overlap splash will not show near as much as white does.

Just my 2c.


No, the underbase is not the white you see. It was a separate white screen.
Yes the white outline is important since these will be printed on navy shirts.

Offline screenxpress

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Re: Halftone Printing
« Reply #11 on: February 11, 2010, 05:09:42 PM »
I understood it's a separate screen, but was the same film source used to make both screens (based on looking at image #2).

I would do that in 4 screens without a highlight white and P/F/P/F the underbase. The white from the second hit is usually bright enough to not need a highlight. Probably going to take a hit from some on saying that.  :D

Scotty, your email is not in your profile. If you wish, can (would) you send me the original artwork?
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Offline scottyjr

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Re: Halftone Printing
« Reply #12 on: February 11, 2010, 05:30:03 PM »
Two completely different films were used for the underbase and the highlight white. The underbase all 80% halftone. The highlight white is the halftone blends and the outline.

Thanks for all the responses but I am still looking for an answer as to whether or not a nice blend can be done without the parameters I mentioned before. Imagine blending white into red. The halftone dots of each color will have to precisely fit into 'holes' not filled when printing the other color. Can this be done without very tight screens, perfect registration, an accurate press, and perfect positives? And if you don't have these conditions then should a printer come up with a different way to print it? And what about four color process? If you don't have the conditions is it even possible? - Scotty

Hold the phone! Evidently I am not correct in my understanding of how these colors merge. As I explained before, I imagined holes left by one color being filled in by the other. If this were the way it worked then layering a positive of one color on top of the other should result in the object of the blend being completely black with printer ink, assuming the colors of the blend started out as 100% at their non blend ends. So I got a surprise when I lined up the blue positive over the white positive. All the dots of the blue lined up right on top of the dots of the white. Now I'm thinkin' that there is no way to get a decent blend other than printing a halftone fade over a solid color. What do you all think? - Scotty

Offline Duke of York

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Re: Halftone Printing
« Reply #13 on: February 11, 2010, 06:46:08 PM »
That is why I have damn near every color of wilflex ink. Most logos use the same colors, most reds are either national or dallas scarlet. Most navys are bears or regular navy.

The problem with process is if you have to reprint a color that ran out of ink or somehow didn't print right, you end up with a funky shade.

This is a spot job all the way.

Do ink shops not ship to Dahlonega?



Process printing is all about consistency and repeatability. While re-orders might not match exactly, it must be close enough to the original to be accepted by the customer. Even ordering ink is no guarantee the color will be correct, but as stated, most customers are happy with a limited selection of colors. Pepsi is Pantone 2945 c.



If i wanted to print a spot color pepsi job, i'd have my employee leave work 1/2 early and pick it up on his way home or have him pick it up on his way in. UPS ground can be as fast as 1 day, but typically 2 day. I've got process color ink sitting in house. By the time i can get a custom ink, i could have the job done.

By using ink on hand, i don't need to charge an "ink fee". Every bucket of ink sitting on the shelf cost money. Either the entire bucket must be paid for by the first job needing it or they are sitting waiting for another job to help pay it off.

If the job was setup for spot color and didn't use halftones, i'd be more for printing the job with spot color than one which has halftones. Printing halftones well, is best done with low pigment inks intended to print with halftones. Printing spot color is best done by high pigment inks. While bucket may say, Pantone 2945 c, that is the characteristic of the ink? Is it appropriate for printing halftones?

I'm still trying to wrap my head around printing the white with a halftone. The whites i use are so thick, i'm lucky to get them to print with a 156 mesh.

For orders over 500 pieces, printing with simulated process would likely make more sense, but at orders of that size, my manual press could not compete against automatics. The market i'm after is in the 36-500 piece range, which are generally too small for art actually designed to be screen printed and where ink charges are offset with less units.

fred


Offline screenxpress

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Re: Halftone Printing
« Reply #14 on: February 11, 2010, 07:14:26 PM »
Two completely different films were used for the underbase and the highlight white. The underbase all 80% halftone. The highlight white is the halftone blends and the outline.

Thanks for all the responses but I am still looking for an answer as to whether or not a nice blend can be done without the parameters I mentioned before. Imagine blending white into red. The halftone dots of each color will have to precisely fit into 'holes' not filled when printing the other color. Can this be done without very tight screens, perfect registration, an accurate press, and perfect positives? And if you don't have these conditions then should a printer come up with a different way to print it? And what about four color process? If you don't have the conditions is it even possible? - Scotty

Hold the phone! Evidently I am not correct in my understanding of how these colors merge. As I explained before, I imagined holes left by one color being filled in by the other. If this were the way it worked then layering a positive of one color on top of the other should result in the object of the blend being completely black with printer ink, assuming the colors of the blend started out as 100% at their non blend ends. So I got a surprise when I lined up the blue positive over the white positive. All the dots of the blue lined up right on top of the dots of the white. Now I'm thinkin' that there is no way to get a decent blend other than printing a halftone fade over a solid color. What do you all think? - Scotty


I think not. All my underbases (under colors) on halftone prints are halftones themselves. Solid white (not underbase) is solid white.
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