1st I will say that I just took the HP-AH off the display shelf in my studio, and did nothing to prepare using it. I grabbed an old bottle of Createx illustration color out of a drawer, gave it a good shake, and added two drops straight from the bottle into the brush. It was THICK, and gooey, for sure. I tested the spray initiation on a piece of scrap paper after working the trigger back and forth a couple times to prime the paint channel. I did have to up the air pressure to between 35-40psi to get and keep a spray. I don't think I took more than about a minute and half to get to this point after sitting at my desk. I only mention this to assure you that I was taking no special care to create a result - just looking for what the combo would do -
At 100% concentration the brush will spray Illustration color pretty reliably, albeit a bit grainy in pattern. It also won't pull the finest of lines without chocking off, but it will work OK for general purpose work. I then cut the Createx 50/50 with 4011. I could obviously get a finer line, but found that paint initiation was actually harder than the non-reduced sample. I eventually settled on basically keeping the air on to produce the sample sheet included in the photo. I started and stopped the lines by pulling back and moving forward on the trigger while keeping the air flowing almost continuously. I then added several more drops of 4011 to the mix to get to @20/80 paint/reducer. One would think it would work easier, but I found I had the same sort of issue overcoming paint initiation - once flowing, it worked fine.
I then switched to my go-to E'tac with Condition-air and their 2050 added to the mix - I also dropped the air pressure to about 20psi - easy peasy, could do lines all day long.
Next was Higgins ink 5 drops ink to 10 water (with 1% flow release added). Super easy paint initiation and no sign of tip dry on the scrap paper.
On both these test sheets (Higgins and E'tac) I was able to start and stop paint flow by either increasing or decreasing trigger pressure to regulate air flow without having to move forward or back on the trigger. If you've ever read about my dots, well, this is why I do it.
I did all of these about as fast as I could without taking any special care, or testing between runs. Just for giggles, I sat back down and added my E'tac mix back to the brush, and reduced pressure to @15 psi, and took my time with a sheet to see what I thought I could really get out of the mix in use -
I've mentioned before, I have a love/hate relationship with Createx. I use it. I use it probably more than anything else - but, I am always fighting it compared to other brands that I also use. By comparison, E'tac is a dream - it's drawback is it does not allow the same sorts of after application manipulation I seem to find myself drawn to in the work... for practice, and testing, I use it before anything else.
Just keep going! The more time you put in, the more you will begin to recognize what and when the brush will do what it does. It is just like putting money in the bank - it all adds up.
to confirm, it's Createx Illustration Color. 
