4 colour process on black

[Rockers]

We did at first underbase with white plastisol 8Sprint white) and then print Union 4 color process inks - the print looks like a turd. Changed the base to discharge and I could almost convince myself that the result is acceptable. The colors are not as bright as the same print on white tees due to the lack of a fully white background, but it`s not bad and nothing like the turdy print using a plastisol underbase. Then we changed to Magna Colour Aquaflex V2 white and boom the print suddenly looks awesome, actually better then the same image printed on white tees. The colors are nice and bright, the print feels great too, and the details are a lot better too. Now I want to print 4 - c process on black tees all the time. But honestly, why does the plastisol underbase produce such a bad result and a HSA base with plastisol top colors makes the print a show-stopper? I tried the same now on our sim process prints. Much brighter colors. All pretty.

[zanegun08]

Smooth Base vs Sandpaper Base

I always toyed with doing the Virus 4 color process system where they do the separations, and you print with their inks and bases.  However the results always left some to be desired, still took 7 colors, and making any adjustments was very difficult.

Where simulated color process it's easier to adjust ink colors, a single screen, and so the extra couple colors needed becomes a wash as didn't typically have to squint to make the print seem "passable"

Post a picture of your results.

[blue moon]

We did at first underbase with white plastisol 8Sprint white) and then print Union 4 color process inks - the print looks like a turd. Changed the base to discharge and I could almost convince myself that the result is acceptable. The colors are not as bright as the same print on white tees due to the lack of a fully white background, but it`s not bad and nothing like the turdy print using a plastisol underbase. Then we changed to Magna Colour Aquaflex V2 white and boom the print suddenly looks awesome, actually better then the same image printed on white tees. The colors are nice and bright, the print feels great too, and the details are a lot better too. Now I want to print 4 - c process on black tees all the time. But honestly, why does the plastisol underbase produce such a bad result and a HSA base with plastisol top colors makes the print a show-stopper? I tried the same now on our sim process prints. Much brighter colors. All pretty.

your base has to be super bright and white for the 4CP to work. Process inks are translucent and the discoloration of the base will pass through the inks and cause problems. My guess is you PFP the HSA and just a single hit of plastisol. Hit the regular ink twice and make sure it's as clean and bright as a sheet of paper and your results will be significantly better.
It is also possible that your plastisol ink is tinted with blue or yellow and is thus creating some other problems.

pj

p.s. as zane mentioned, post the pictures!