Creating custom halftones using Photoshop filters

Here is a tutorial on how to create some more interesting halftones when working with screen printing.

So here is an illustration that is in progress. Currently it is using solid colors and lines, but we want the gas tank of the motorcycle to appear grey. However we will be printing only using black and red ink. By creating a halftone we can get that effect. Photoshop can easily create a standard halftone pattern, but we want something that isn't your normal halftone, and has a little more texture.

So first I painted an area of black with a brush in photoshop using a soft edge.

Next I blurred that layer and cut off the bottom edge to align to the bottom of the tank.

Next I created another layer behind by black layer and filled it with white, I turned down the transparency of the black layer to get more of a grey, and then combined the two layers into one layer. This is necessary because the filters we want to use are not compatible with transparency. I deleted around the solid white shape that I wanted so that pure white didn't fill the entire image.

Now go to Filter > Pixelate > Color Halftone. The default Max Radius is 8 pixels. You may need to play around with this to get the desired size. Because we are creating a single color halftone all the screen angles should be the same number. Otherwise the halftone will be in CMYK. I like a 45 angle.

Now technically we do have a perfectly acceptable and printable halftone. But since we are going for something a little more unique we're going to keep working on it.

Next go to Filter > Pixelate > Mezzotint. You have a few options here, and each can be interesting depending on what look you want. I chose Grainy Dots.

Next I added another Mezzotint fiter to the entire tank, and the cowl behind the seat to give them a light grey look.

Next I painted white over part of the halftone to give some separation and dimension to the tank. 

You can also invert the first halftone layer we created for a different kind of look. 

Next I "painted" some texture behind the engine of the bike, and shadows under the wheels. 

I used a Photoshop brush with a Scatter effect, and combined that with a Mezzotint filter.

 I've been using a set of brushes called the Nagel Series which you can find here. I've modified the settings of most of the brushes to accomodate a more solid spray. Most of these brushes with their default settings will give you results that are too soft, and not solid in color for screen printing.

This is just one method of creating a halftone with more of a texture to it, that will give you some interesting results for screen printing. You can combine these methods with photo textures you already have, multiple layers of grain, or custom brushes to get even more effects.