No problem on the questions but if your going to pick my brain I can tell you it won't take long!
Not much up there anyway.
After the EPA banned lead PPG reformulated DP epoxy's to DPLF(lead free) The adheasion is not as good as it was before this,still a good product just not like before.Dp had such good bite before the change that if you got it on glass it would stick and be very hard to get off. Using the acid etch(dx 1791) gives it a boost in adhesion.
I don't use any of the rust stop paints on any area that get's finish paint, only on interior panels like inside frames,doors ,drop extensions,ect.
When these products first came out they said you could just paint over it (didn't work),then it was wait until it dried some and paint over it(didn't work), then they said you had to spray a tie coat to paint over it. If you have to do that much work to use it I decided to just clean it very well and go to regular paint system for less hassle.
For example I coat the lower inside area of the door skins (inside the door)on all cars to stop any embedded rust and protect from any rust bleed later.
If it is cleaned enough there is no need for it and it voids the paint manufactures warrenty even if it is not the problem. But it is very useful for hidden rust prone or hard to clean panels.
Hope all that helps.
Dave
PS GREAT KNOWLEDGE.
Remember I'm just a farmboy.