if you add transparent base to regular speedball colors and over print them, will it make different colors, or does it have to be process colors? like could i do a yellow over blue and get a greenish color or vice versa?
yup. you can use the trans or extender base for process or non-process speedball inks no problem. i do it all of the time. the non-process inks tend to be more opaque, so you might have to use more trans/extender base then you would with process inks. and water if you want.
oh cool thanks. so what would be the proper way to use a blue and yellow to get green? thin both the blue and yellow out and print yellow on blue? or do you even have to thin the blue out? or do you thin the blue and print it on the yellow?
i usually do light over darker for real overprints where i am definitely trying to get another color, (but that's not always always the case, just a basic guide/premise) and andy is right, yellow over blue will be a brighter green.
you can thin the bottom color out, and sometimes i do if i want a nice light color, but more often i just make sure that the top/overprinting color is transy enough.
i've printed process /transed out inks over non-process ink too, and that usually works great. though once i had some weird waxy resist action in a corner of a poster. that was weird. didn't happen all over the print and has not happened since.
heh, i hear you. when i have a print or a poster to do with good, heavy-duty overprints action i get excited too. the last 2 posters that i've printed (the joggers/scout niblett & tegan & sara) had big overprints that cheated out a 4th color. i love 'em.