Molding dash plastic

I have been doing alot of plastic molding on numerous cars and having problems with chemical reaction and paint bubbling. what products do you guys use to work with interior plastic?

clean everything its probably just a little dust and it will bubble i wipe everything down with paint thinner and spray an adhesion promoter

Im using 3M brand 4040 and 4058 right now and having problems being able to paint it without bubbles. Most of the reation is happing when the vehicle is outside (im in AZ) were it is hot. I need some type of body filler or glazing putty that will bond to plastic.
I am cleaning everything I dont think that

fibertec works pretty swell

Is fibertec acutual filler or is it an addative for fillers. Were can I buy it from and does it have any flex?
Thanks alot for all the help