This thread is intended to help you diagnose your own first few problems you might experience while starting out. Typically all this information is available to anyone willing to use the search feature, but this will be a crash course that can be brought up quickly as a reference.
For those who are kind enough to contribute here, try to keep the information as concise as possible, and limit it to the problem and solution.Underactivation
This will be our first topic, as it is the most common. It is characterized by jagged holes, appearing randomly in your print where the base color shows through the print. These holes may not show up until the rinse stage, when you go to clean off the PVA from your dip. The film acting like it is still too solid while trying to dip through it can also be a tell tale sign. Underactivation is caused by not getting enough activator onto your film before you try to dip to it. The ink needs a solvent sprayed on to it to turn it back into a liquid, that can bite into the paint, and adhere correctly.
Some causes of underactivation are:
Your activator gun's material flow set too low
Use of aerosol activators (they don't throw a consistent, or wide enough pattern)
Your activator gun's pattern is not shaped correctly
Your activator passes are too quick
You are not making enough activator passes
You are holding the gun too high
Some solutions to underactivation:
Increase your material flow to your gun
Get a good HVLP or LVLP gun to spray your activator
Watch a video on how to set up your activator gun
Slow down the speed that you apply your activator
Change direction and use the "Tic Tac Toe" pattern when applying activator
Hold your gun at shoulder height, the air from the gun should not move the pattern.
Underactivation showing up after rinse
A film that requires more activator than most
Most of the dip looks good, but just a few spots that are bad
Wood grain patterns use alot of ink, so they need alot of activator