Canopy problem with an Airfix Piper Cherokee

Hi Dans, are you talking about the sink marks (where the plastic has shrunk and created hollows in the panes) ? if so i have the same kit with the same problem. as you intend to paint out the windows your method will work and if you use some rough paper (say about 80 to 100 grit) the putty will bond quite well and when dry use 1500 grit to smooth it out. if (like me) you wanted to keep the windows clear you could replace them with clear plastic card. hope this helps.....Greg