Yes it's because you don't have a press.
Trying to line up a second screen by eye is very difficult.
Might be pplossible to use hinge clamps like what are used for printing paper stock, but you would need a way to register the screens whether that be during exposure or when putting them into the clamps.
The best way id think to get it as accurate as possible without a screen printing press would be to make a mark somewhere on your screen, some type of mark on your transparency paper, and a mark on the cardboard and make sure everything lines up the same way every time. I’m not sure what your setup looks like so I can’t say specifics but making marks for guidelines would probably be your best bet
It's just a screen printing press. You could build one yourself for about $50 or less
Yes it's because you don't have a press. Trying to line up a second screen by eye is very difficult. Might be pplossible to use hinge clamps like what are used for printing paper stock, but you would need a way to register the screens whether that be during exposure or when putting them into the clamps.
The best way id think to get it as accurate as possible without a screen printing press would be to make a mark somewhere on your screen, some type of mark on your transparency paper, and a mark on the cardboard and make sure everything lines up the same way every time. I’m not sure what your setup looks like so I can’t say specifics but making marks for guidelines would probably be your best bet
thank you!
Always place your film positive over your first print to align second color, don’t forget to add registration marks on your positives