Let me offer a little perspective If I may. I have only shot Stewart Systems; I have not painted or covered with PolyFiber. As such, If I were to try to use Polyfiber I would run into problems; probably the same issues I first encountered with Stewart Systems. It would take me a lot of time and practice to get consistent since I have no idea how to spray a solvent based system. I'm sure my first attempt would have problems. It takes practice to get to the level of the guys who shoot and paint on a daily basis. This is not an excuse for issues some guys have; it's just my perspective as a teacher for 30+ years; there is a learning curve to everything. I am more than happy to help anyone who is having issues.
Let's talk about orange peel; an issue for many users. Orange peel starts with your first fog coat, not your last wet coat. If there is any gloss to your fog coat than too much paint has been applied. Fog coats are quick and light. First should only cover to about 30% color saturation. You should still see your base color as the primary hue after your first fog coat. It should look like wispy clouds way up high against a blue sky. Fog coats need to be so light that the paint sticks and does not move. If it's too heavy, it tries to flow than sticks and starts the orange peel. Each coat will than increases the amount of orange peel. You don't use much paint for the fog coats. On the wing I posted pictures of here, I only used 400 grams of paint for three fog coats, and I had paint left over. That's not a lot of paint. For me, and this is just me, I shoot the three fogs on a wing than stop. I come back 24 hours later and inspect for dirt or any other issues and than scotchbrite and dry sand the surface lightly, blow and wipe, and clean the wing for final coat. That takes me about two hours. I get tired after three fog coat and I need to be fresh for the wet coat. If I messed up and have orange peel I remove it in this sanding process. I figure that time into any estimate I make for a wing. I than mix my paint and do one fog and than one wet coat. Lighting is key and a low angle viewing to see if I have dry places with not enough paint is critical. My mix with the DuPont viscosity cup for the silver metalic was 27 seconds. But, on the metal Ford cup, the same mix was reading 24-25 seconds. Turns out, not all viscosity cups are the same as they are calibrated with mineral oil, not paint .... go figure that one out. The higher numbers have worked well for metallic as it flows different witn all the suspended metal in the paint. Solid paints I run a lower number, but I like 24-25 seconds with my DuPont cup (no longer available). I also upped the pressure from the mfg recommended 23 psi and use 27-28 psi. I find it attomizes the paint better (use the 1.3 tip). I suspect they recommend 23 to get the lower voc's to make the EPA happy vs unhappy paint. I use a material setting of about 1-1/8 turn for foggs; 1-1/2 for wet on the FinishLine 4 gun. I think one of the variables we all have here is compressed air temp and moisture in the air. I use a homemade cooler where all my air passes through an automotive a/c condenser before going into the storage tank so my air is very cool and dry. Does that change my numbers some, I think it might. You will have to experiment with your set up. As stated above, material setting is completely different on different guns so you must figure out your gun. For the final fog and wet coat, I used 900 grams of paint for this wing, over twice the original fog coats. If you are doing the paint in one setting; make sure each coat tacks up so there is no transfer to your knuckle; time will vary with your temp and humidity so be patient or you will get solvent pops (water is the solvent). I typically shoot around 70 degrees and humidity around 60%; I won't shoot over 70%. I also write everything down for the different colors I use to keep track of my numbers for repeatability. Everytime I shoot a new color, I shoot a test panel; cheap insurance.
I wish we could make a paint that is as simple as 1+2 = 3 but there are just too many variables for that to be realistic. Andy usually has "practice paint" in the warehouse available. It's just overstock or wrong color match, etc that he sells at a very reduced cost. Before you give it a go on airworthy parts, try it out on a practice panel first.
Please let me know if you are really stuck and i can help you get through it. For me, eliminating solvents in my shop was the biggest factor in product choice. If the system you are using works and you feel safe using it than stick to it. I suspect it won't be long before solvent based paints are more difficult to purchase, just like the trends for oil based stains and other paints. I hope this helps a bit.
Marty57
