Help Prepress and Production Help You

A halftone test file will help your team learn to ‘hold the dots.’

Experienced color separators often cringe when they get an order from a customer who is new to printing with halftone dots. The giveaway is when the client says they don’t do much halftone printing and don’t own mesh higher than 156. The separator can send over a great set of color separations, but the client won’t be able to hold any halftone dots lower than 15% to 20%. If the separator recommends a 230 to 305 mesh, the client still uses a 156. That means any areas of the separations with subtle details or light shading will be gone. And the client will invariably call and complain that the final print doesn’t match the artwork.

When this happens to me, my polite response is: “Compare each film to the final print. Is every little halftone dot on the film on the print? Did you compare the film to the screen when you were done washing it out? Did you ‘hold the dots’ on the screen?” That means the halftone dots on the films must end up on the screen.

Typically, the client will tell me they don’t make the screens. That happens in a different department. However, as an artist, it’s your job to help your screen-making and production people show you they can burn and print what you give them on the films.

This is an easy one. All you have to do is give them a halftone test file that you can easily make in Adobe Illustrator, Photoshop or Corel Draw. You can make it with squares filled with gray levels of 5% to 90%. If you don’t know how to fill squares with pre-halftoned gray levels, then just make a test file with normal gray levels and output it at a variety of halftone line counts. I like to use 35, 45, 55 and 65. That gives you a good range. If you know how to fill a box with pre-halftoned gray levels, then you can make one test file. You can also download a test file here.

Tell the screen department to burn it, and then pass the screen to production to print it and bring you back the print, NOT on a test square, but on an actual shirt. You’ll find that in many cases they simply expose too long or have their emulsion too thick – or run the squeegee pressure too hard – and that the small 5% dots don’t show up and everything 70% and higher is a solid. You can learn a LOT from a simple test film. If your colleagues can’t hold the dots from the test film on the shirt, then they can’t on a set of separations.

Once you get them to hold those dots on the screen and print without mashing them into the shirt, your seps will look much better. Yes, there is more to this – like proper screen tension, low off-contact and more. But let’s start with the basics of trying to burn down to a 5% dot and having the shadow end of it not close up when printed.

If you’re in a larger shop, be prepared for a little resistance. Screen room and production people generally don’t like the art department to question their jobs. But if you persevere, everyone learns and everyone wins.


Scott Fresener has been in the industry since 1970 and is the co-author of How To Print T-shirts For Fun And Profit. A popular speaker at trade shows, he runs the website www.T-BizNetwork.com. Reach him at scott@tbiznetwork.com.