Author Topic: Very very basic question about printing spot colors  (Read 446 times)

Offline 1984solar

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Very very basic question about printing spot colors
« on: February 10, 2019, 10:15:30 PM »
lets say i was printing the image i attached on a black shirt. can you print flash print the white then do the red over it? or is the gerneral method to print the white flash it then print the red then a third screen over the white to get an opaque white? what are your thoughts on which method is better? obviously the first way would save a screen so can it work like that? also i was curious as to flashing the underbase in preparation for printing a color on top of it... what is the temperature your going for of the white ink and for how long?

bonus question.. if i wanted the white text on the right to be green would i have to flash the red after its printed or can i print wet on wet? would i be able to print wet on wet if its a butt registration of two colors on black? thanks for helping a noob  :)


Offline Sbrem

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Re: Very very basic question about printing spot colors
« Reply #1 on: February 11, 2019, 07:53:59 AM »
you got it, don't over flash, and the red will stick much better. If you over flash, the top colors will come off in a few washings.

Steve
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Offline mooseman

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Re: Very very basic question about printing spot colors
« Reply #2 on: February 11, 2019, 09:10:38 AM »
We have done it each way you describe. The long way is (in our experience ) the most successful way and we often go that way.
While a longer process of white under, flash..... red flash...... then white finish will require 3 screens and some extra steps we believe you will get better and more consistent results across your order.

We would white under base with a 230, flash red with a 156 flash, finish white with a 156. Be sure to trap (or choke I never get the term right) your white under a bit. We always add a contour to the choked element, instead of adding an outline that equates to about .5 to .75 points depending on how big the print image actually is. Tight screens help and are always a plus.

Here is some hidden value that you may consider in "taking the long way" in this process. While more work and more time and an extra screen you will see and discover more about screen printing and the way it works best for you.
We are still pretty new to this process but the one thing we have learned is that we all do the exact same thing but in 100 different ways to get to the same result. 
It is all part of learning how you deliver a quality print to your customers.
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Offline Prince Art

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Re: Very very basic question about printing spot colors
« Reply #3 on: February 11, 2019, 10:34:15 AM »
There's more than one way to skin a cat. All of the combinations you mentioned can be done. Which one is best is determined by the specifics of each job.

For example, using your red/white image, I would look at the length of the run. If it was short (a few dozen), I'd probably use 2 screens: white-flash-white-flash-red. I'd probably use 200 mesh for white, 156 for red. Reason = the extra flash doesn't waste as much time as the prep/setup/teardown/reclaim of a 3rd screen. But that's only if I think the printed results will be satisfactory this way when considering the subtrate material, inks used, and specific artwork. In general, the way Mooseman described it is better: base white, flash, red, white.

As for when to flash vs when to print wet on wet, it depends largely on the ink and the design. Not what you asked about, but simulated process & true process are intentionally printed WOW - and the inks used are formulated accordingly, and the designs are created/sepped accordingly. But with spot color, that isn't always the case. The simple answer is: as often as you can get away with it, don't flash between colors; but sometimes its necessary*. Certain butt-registered colors may get muddy where they meet if you don't. (In my experience, yellow is particularly susceptible to this.) Or, your design may include large filled areas which will cause the shirt to stick to the next screen & lift if you don't flash.

(*You may see it argued that flashing between colors shouldn't be necessary if you've got all of your printing parameters precisely dialed in. Perhaps that's technically true. But practically speaking, many of us aren't working with ideal equipment or perfect technique, and flashing is sometimes part of getting the job done.)

As for flashing temp, I don't have a spec. "Gelled, not fully cured" is the rule of thumb. If it is wet to the touch, flash longer; if it is so dry that you can't smudge it even if you try, back of a little. Other folks may have more precise advice!
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Offline tse1990

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Re: Very very basic question about printing spot colors
« Reply #4 on: February 11, 2019, 10:43:51 AM »
lets say i was printing the image i attached on a black shirt. can you print flash print the white then do the red over it? or is the gerneral method to print the white flash it then print the red then a third screen over the white to get an opaque white? what are your thoughts on which method is better? obviously the first way would save a screen so can it work like that? also i was curious as to flashing the underbase in preparation for printing a color on top of it... what is the temperature your going for of the white ink and for how long?

bonus question.. if i wanted the white text on the right to be green would i have to flash the red after its printed or can i print wet on wet? would i be able to print wet on wet if its a butt registration of two colors on black? thanks for helping a noob  :)


In our shop, we would look at how many shirts are in the order and then decide if we wanted to send the white twice around (White *Flash* White *Flash* Red) vs once around (UB *Flash* White Red). At about 40-50 shirts the job prints faster using a top white (for us).


Another factor is if the UB is opaque enough with just one pass for the red to look good. That's on your end, you know what your capabilities are.


Flashing will take some experimenting and perhaps require adjusting halfway through the job as your platens heat up. Quick and dirty test: After the flash, let it cool for 15-20 secs, take your index finger and put 1# of pressure on the print, lift and check. If there is white on your finger you have UNDERFLASHED.

If nothing comes up on your finger, next test: Take your thumb and put #5 of pressure on the print area and twist. If you get a LITTLE/FAINT white you're at a good spot. If nothing comes up you have OVERFLASHED.


There are visual ques that go along with this that you can see while printing. Rough looking print that red shows up on, you're OVERFLASHING. Muddled looking print where red is patchy or pink, you're UNDERFLASHING.

Good luck!






Offline 1984solar

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Re: Very very basic question about printing spot colors
« Reply #5 on: February 12, 2019, 12:04:26 AM »
thanks to everyone who replied. that was helpful