Using Spot Colours in Photoshop

Channels > New Spot Channel

Can overlap colour like 'multiply mode' - if want it to be solid colour put in 100% in solidify option when choosing colours.

Can get tints of colour when you change the brush colour to gray.

Save as .psd or .tiff (make sure spot colours is ticked)

Document ink all about halftones - can print positives for screen printing.

Freq 50-65 lpi - as good as you can get with screen printing (finest)

Angle (if ink contains tints) - 15, 75, 105, 155 (for full CYMK)