You need to use a white underbase.
A white base is one option, but there are inks are are called opaque, which are thicker and work well on dark colors without a base. We used Union PADM brite red on black shirts, 110 mesh, print, flash, print, and they came out great. Also bear in mind that if you are printing on 50/50 shirts, you may have the black dye gassing into the ink when you run the shirts thru your dryer, so in that case, ask for a low bleed ink. Check out One Stroke Inks, they have some very good inks, and offer a return policy whereas if any ink they sell doesn't work for you, they take it back & either send you another ink, or refund your money. They are very easy to work with.
You could add a stroke to the red so you have a little wiggle room in the print. If you want to try an underbase.A white underbase isn't really an option with the press I have. I just have a 4/1 logos table top press. Getting two prints with two different exactly on top of each other would be inpossible with this press.
You could add a stroke to the red so you have a little wiggle room in the print. If you want to try an underbase.
what kinda press do you have?
I have printed Lawson Rojo Red semi-successfully on black shirts with no white underbase before. Try playing around with your stroke angle/flood method. I think I did a standard stroke, flash, then a pretty heavy flood with a second stroke at a very shallow angle to cut less ink and it turned out acceptable.