Four Color Process Screen Printing How To
Loading the colors of your inks into the Photoshop software program ensures a more accurate representation of what you will see on press. Otherwise, the colors used in Photoshop, SWOP (standard web offset printing standards), may vary from those values displayed with your inks. The film output will not be correct to your ink mixes and the secondary and tertiary colors won't match to your inks; but instead, they will match the SWOP mixes. For Example: An orange according to SWOP may be correct at 75% magenta and 25% yellow (film dot percentages); however, the same orange might read as 60% magenta and 40% yellow according to your inks on press. The orange, therefore, will not appear the same and you will have to adjust the film percentages - which means back to the art room. If the primary colors are entered correctly, you save a tremendous amount of time by avoiding unnecessary film adjustments.
Cool White Fluorescent (light where garments are viewed at point of purchase).
Method of Entering Information
- Open Photoshop.
- Click on File > Color Settings > CMYK Setup
- Check the L*a*b* coordinates box.
- Open Ink Colors and choose Custom (at the very top of the list).
- A custom box appears, like the one below. Click each box and enter the color values in the appropriate box.
- Click Save and create a new file called "Color Values." Label this file as "IC CMYK Values."
Each time you enter Photoshop, you will need to check to see that you are working with the correct values by going into File > Color Settings > CMYK Setup. IC CMYK Values should be displayed. If not, simply click Other > Load > Look under Color Values file and open IC CMYK Values and click OK; and this will automatically reset the values when you need them.
Pro-Brite Process Color Values in Adobe Acrobat's Portable Document Format (PDF). Acrobat reader is available at no charge from Adobe Systems.
305 mesh count. 100% Saturation.
Half tone line. 55
Halftone angle. 22.5
Half tone shape. Either ellipse or round.
Explanation of print format.
Properly known as Tonwertzuwachs (German) that literally means a "tonal value increase" has gotten a bad name for all the wrong reasons. Without dot gain, images would not achieve higher values of tone and color on press producing much less pleasing prints. Dot gain is actually a printer's best friend. Tonal Value Increase should now sound good to you.
There are two forms of dot gain, physical and optical. Physical is the actual spreading and increase in size of ink as it is absorbed and reshaped on press. Optical is the perceived increase in size of a halftone spot due to ink pile up that cast a shadow making the ink spot (halftone) appear to be larger that it is. Most printers only discuss physical dot gain because it is the most obvious result.
Understanding where the fear/misunderstanding of Dot Gain came from:
Once you properly understand all this you will no longer have to work in fear of dot gain. Discussed earlier, the proper effects of printing using the Flemenco style of single angle spot (halftone alignment) is clarified further. This has been known to be proper since the late 1800åÕs, so why do so many printers use rosette patterns? Lack of education is the hard truth. Improper explanation by others is another reason.
Here it is, even CMYK (a subset of RGB light) first conceived in the late 1800's was properly printed in the single angle for accuracy. But, by the turn of the last century (1900) when CMYK printing was gaining popularity presses that could not hold the registration would cause a terrible moiré. Printers decided that at a high line screen (133 and up) they could produce an acceptable MOIRÉ that would be consistent on press. They invented the rosette and target shaped alignment of four screens set at different angles. So you see, even the conversation of printers that claim to have come up with their own special and secret angles when printing to eliminate MOIRÉ are really printing a MOIRÉ anyway, just one they feel is acceptable. Now that you have this straight, forget it and we can all have a good laugh about ourselves.
Printing in the Flemenco style accepts up to 40% press gain without the loss of detail or the corruption of color due to Tonwertzuwachs (dot gain). The reason is that there is a lot more room between each spot (halftone) allowing for the physical gain of the ink that eventually increases tonality and color. With a rosette pattern the space between each spot is greatly reduced due to the angle shifting. Since screen print presses are high saturation devices that top out around 33% Flemenco style printing never over gains allowing for very deep clean runs with little to no downtime. Rosette printing has trouble with as little as 15% dot gain. Presses have for a long time been able to hold tight registration and printers of all fields should have converted back to Flemenco but they followed old thinking with out asking why. The proof that Flemenco is as proper to day as it was back then is that with today's new high-tech digital presses print using single angle (continuous) configurations and not rosettes. Mystery solved, pass it on.
Print your Process and all other separations even CMYK using single angles and improve your prints. It is even advised that you print your color prints for a color LASER printer using Flemenco. A simple test with a CMYK file at 55 lines screen, one as Flemenco and the other with standard rosette angles will prove it all. Now you have the documentation from the SPVR manual telling of the reason for printing using one angle (Flemenco) and that should peak your interest. The benefits from doing it right are numerous. Passing it along to clients is worth a small fortune in time and money, not to mention respect. So many printers suffer because they are flat out doing things wrong and printing CMYK with multiple angles is just the worst thing you can do.
Printing with a single angle.
1. Creates a better wider color spectrum.
2. Sharper Cleaner prints
3. Prevents color casting such as magenta and cyan shifts
4. ELIMINATES screen moiré. Its hard enough to get a single angle to burn perfectly to a mesh no less 4 angles all trying to work together. Since a rosette is a moiré and we use low line screen images suffer terribly from the use of them. Starting out with what you seek to prevent is just wrong.
5. You no longer need to use elliptical dots that create their own disturbance pattern. Use round. Elliptical was invented to address the terrible dot gain issue created by using a rosette pattern. Elliptical dots do not burn better than round, that is false and totally not why they were invented. Round is much better for many reason. Dots don't capture mesh fiber, holes are exposed to the emulsion layer so round works just as well when used with the proper mesh count and coating. Elliptical dots were supposed to reduce "physical" (not optical) dot gain between colors in a rosette. No rosette, no problem.
6. Dot gain is a printers best friend and not the enemy. The proper use of single angle puts dot gain to its proper use of expanding the "printed" color spectrum. Dot gain is only a problem when you use a rosette.
7. Everything about AccuRIP right down to the "lock screens" feature along with only having a single entry field for "angle" is there to enforce what is proper and make people to do the right thing even if they don't know why. Ultimately it would be best to eliminate the "lock screens" option making in mandatory, but people are people and they would "freak" so we don't.
8. Using lower line screens with Flemenco produces better prints then higher line screen with rosettes. This is also a major "benny" for printers.
9. Using a single line screen allow printer to develop tonal under bases much like those in SPVR to print CMYK on darks. Also enables them to make top white screens. Rosettes force printers to lay down heavy "sheets" of white or to discharge.