Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
Of course ANY ink can be made to look better than another if the printer so desires. The 2 or 3 inks in a screen method is designed to give an ACCURATE comparison of bleed resistance/opacity of 2 or more inks under the same printing conditions. If a printer wants an ink to fail a comparison test, ( and some do) there are a million ways to manipulate a comparison test be it on an automatic or manual press. More often than not, if an ink shines in a side by side comparison, it will on an automatic press. And as for thick sticky Polyester white inks that require slow squeegee speeds with lots of pressure,,, we do not make any of those Rocky
I guess I am biased towards developing high performance low bleed inks for polyester. You need not get quite so technical just to measure bleed resistance/ opacity of one ink against another especially for 100% polyester garments! If a white inks has crappy bleed resistance, a basic print test is all it takes for that to become apparent. Not every printer on this board runs 15 automatics!!Now if you want to talk big printers,,, we have developed several new ink series working with some of the largest printers in the USA that are bleed resistant enough for 100% poly, but soft enough and safe for 100% cotton. Saves a lot of ink room space if you can use the same ink series on everything! Oh yeah they print like a dream on a manual or automatic.
In most circumstances dry white pigment will run roughly 1/3 of an inks formulation. But just as important as pigment loading is the type of viscosity an ink formulation has. The push to make screen printing inks non-phthalate really hurt plastisol ink rheology(viscosity) especially for inks designed for low bleed applications. Believe me, after exhaustive research, I have finally hit on combinations of ingredients that give excellent viscosity, printability, opacity, and the best bleed resistance available. You can formulate a white ink that has considerably more white pigment, but if the rheology is not right, the lesser pigmented white will always have better opacity. As for most black inks the actual dry pigment loading is roughly 2 percent.
Your right Rob, I should have been more precise. I bet most screen printers print on lots of poly,, be it 50/50 or 100% so I just assumed when printers test a white ink, that is the first thing that crosses their minds. After all anyone can make a white that works on 100% cotton. There is a reason though that there are tons of screen printers out there switching to our white inks and using OTHER ink manufacturers colors..... You can make a marginal color line work if you have an excellent white ink to go with it. Of course I am sure you knew that already! By the way I thought one of the few good points silicone ink sellers used to justify all of the mixing,, refrigerating, using before it cures headaches was that it was BLEED-PROOF.... So whats up with the RFU Gray underbase for bad bleeders,,,? thought that didn't happen