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Gradients and Halftones in Screen Printing
There’s some good conversation on Blake’s post about how to take your t-shirt artwork from good to great.
Jake asked: “What is the best way to blend colors using half-tone patterns that will translate well to screen-printing? Any common mistakes or things designers should be aware of?”
Well Jake, here’s the (really long) answer to that.
Let’s start with a brief explanation of what exactly halftones are:
Basically, halftones are regular patterns of tiny shapes (dots, ellipses, squares are common) that taper out to create the appearance of a color fading (or graduating) to white or another color at the edges.
Take a gradient (like the above left) and render it as a halftone pattern, zoom in a bunch, and it would look something like the above right.
When a screen printer outputs a graphic that contains gradients onto films (which are used to burn screens – which is what the ink goes in), what they’re really outputting are these halftones. If you look closely at a screen printed tee that has gradients, you can actually make out these patterns:
But seen from a distance, it makes a perfect blend. You can see it best on shirts that only have a few colors and are especially ones printed on white:
Printers can adjust the angle, frequency and shape of these dots to increase or decrease the dot size of the halftones. Larger dots = more space in between them, more visible gradient appearance; Smaller dots = less space between them, tighter, smoother gradient appearance.
A lot of this is technical stuff that you never need to worry about as a designer (your screen printing will do all the work with setting up the correct halftones to make your gradients print well) but you can make their life easier by prepping your artwork correctly and understanding a little bit about the process.
Here’s some things you should know about printing gradients:
- Understand Mesh Size
The screens used for printing come in different mesh sizes ranging anywhere from 40 to 230. The lower the mesh size, the larger the holes in the screen and the more ink is pushed through to the shirt.Gradients require the opposite end of the spectrum: high meshes that don’t let a lot of ink through (otherwise the little dots all blur together and look like a blob). Not all screen printers have these higher mesh screens required to do gradients, which is why many of them don’t.
- Be aware of the trade-offs of mixing large solid areas and gradients in the same color
If you have a color in your design that covers a large of area and has gradients, the printer is suddenly faced a dilemma. Do they chose the high mesh screen that will print the gradient without blurring (but lay down less ink in the places the color has large coverage)? Or do they chose a lower mesh that will give good coverage to the large areas but potentially blur the halftones.Generally, there’s a decent in-between option, but most printers will opt to preserve the halftones. So you may notice some lighter/sketchy coverage on the large solids.
- Halftones and Underbases don’t mix well
An underbase is used when printing on dark shirts to provide, you guessed it, a base for the design to keep the colors from getting absorbed into the fibers of the shirt, and preserve vibrancy. It’s usually a white or light gray, and underlays the entire design (or most of it, depending on the color of the shirt and colors of ink being used). Because you’re covering such a wide area with ink, underbases are generally on a lower mesh screen, which almost never agrees well with gradients… which brings me to our next item: - Sometimes your solids and gradients can (and should) be printed separately This generally adds to the cost of printing your design (because most printers charge per screen), but it can be a good solution if you have issues with coverage, or a design that’s going to have a white underbase and gradients that fade from color to the shirt.The solids are outputted on one screen with a lower mesh, and the gradients are printed with the required higher mesh.
And here’s some things you should do with your artwork to make outputting your gradients easier:
- If you’re working in a vector program, make sure all your colors (including gradients) are in PANTONE colors.
This includes using a PANTONE white for gradients that go from a color to white. When prepping your artwork, the printer needs to convert all RGB/CYMK colors to PANTONE for output, and they’ll hate you less if they don’t need to go through and replace colors in the 200 objects of your design that have gradients. - Don’t flatten your image if you’re designing in Photoshop or another bitmap editor
This is good advice for any design regardless of whether it includes gradients or not, but it’s significantly easier to split apart the colors of a gradient when they haven’t been combined together. - And finally… don’t try and use gradients on highly detailed, small areas of your design
Remember the dots from the up close picture of a halftone? These dots can only go so small, and in smaller areas of your design it can be hard to concentrate enough of them to visually see any time of transition.
Wow, thanks for the long but thorough answer. I’m sure this will be a valuable reference for many designers, including myself!
cheers!
Yeah, you’ll be careful what you ask next time, won’t you? ;)
Hello Liz, wow, you are a veritable font of information on t-shirt printing, and articles like this prove it. I’ve considered getting into it myself in the past but never had the guts lol.
Anyhoo, please keep these articles flowing; I’ve added your site to my daily reads and also linked to it from my own blog!
Sion, thanks!
Funny thing is… I just ran across your site a few days ago. It’s like my new favorite place to visit.
It’s pretty ‘awesome’ isn’t it ;) Sion also has some pretty sweet prints over at ubiki.com. I have one of those green monsters staring at me right now.
Liz,
Way to bring it with this one! Talk about getting down to it. :)
Blake
Do you have a guide for how to convert gradients into half tones?
[...] you may enjoy. In my opinion, the best part of her blog are the descriptive/tutorial posts like Gradients and Halftones in Screen Printing (which I’ve already read three times) and So You Wanna Design T-Shirts? Part 1: There are [...]
I have such a beginner question. I have been working with mainly vector images BUT if I do some effects in 300dpi and separate my colors in photoshop can this be translated by a screen printer? Or should I always use vector for screening?
Hi Mija, it’s actually a great question – Photoshop is equally adept at processing images for screen printing, as long as you prep the file right.
Definitely make sure you do all you effects at 300dpi AND the size that you want them to be when they’re printed (because photoshop bitmap graphics can’t be sized up.)
Also make sure you don’t flatten your image (so keep all the layers) – it’ll make the screen printer’s job much easier.
Hope that helps!
[...] tons of tutorials online for what you’re trying to do. This is a blog that popped up on Google: Gradients and Halftones in Screen Printing | Pop Culture Tees Be sure to post pictures of your [...]
[...] Gradients and Halftones in Screen Printing [...]
Hi there just a quick question regarding the Pantone White you described in the article: I recently had to supply artwork for a screen printed CD (on-body artwork). One of the inks was to be white and I was told to mix a new spot color (I used a light grey) and rename that plate “white Ink”. Would this be the same for t-shirts, or is there a better way to do this? Like is there a “Pantone white” in one of the Pantone colour libraries?
Thanks!
Hey Michael –
Same way for t-shirts!
CorelDraw (in newer versions) actually has a “transparent PANTONE white” in their palettes. I’m not sure if the same goes for Illustrator.
You’re definitely right about using another spot color for “white” if you don’t have a PANTONE white swatch available.
When I was the in-house artist at a screen printing shop we always used a lovely shade of bright blue.
The other benefit to using an actual color (as opposed to a white) is that you can actually see the white areas on the design when you’re working on a white canvas.
Thanks Liz :) I’ll have another look in Illustrator, maybe the newest version has a Transparent Pantone White in the palette.
[...] http://www.popculturetees.com/2008/09/17/gradients-and-halftones-in-screen-printing/ http://www.10e20.com/blog/2007/02/16/halftone-and-bitmap-effects-photoshop-tutorial/ http://theartofapparel.com/index.php/designing-with-halftones/ [...]
[...] and thats it ?" 4- you will need halftones for a gradient. this link explains it a bit… Gradients and Halftones in Screen Printing | Pop Culture Tees are you asking about how to color separate gradients? __________________ [...]
This is a great reference Liz. It is such a complex issue for anyone who does not have a screen printing background. I think you have covered everything here in a very clear way. If designers are creating images in illustrator or photoshop they do not have to create the actual halftones, the screen printer will print out the gradients using a RIP, if designers want to get an idea of how the half tone will look they create a bitmap of there gradients in photoshop, the most common settings used by screen printers on textiles are 55lpi eliptical or round. Thanks for the great blog.
Hi Mija
I find illustrator the best for originating the artwork, you can then take it into photoshop for further effects including using plug-ins.
I am trying to find a chart that gives the appropriate mesh count to haltone lpi.
can you help
thanks
Gil
Hi Liz,
Talk to me about LPI verses screen mesh to avoid morea (SP) patterns. I can’t seem to get it right and the guy burning my screens is getting sick of re-burning cause I’m not happy with the new design
I agree with you! Great job!
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