Hey Garry.......
I seal the fuselage formers with catalized primer such as PPG K-36 or PCL poly-primer. It is impervious to jet fuel and is easily applied by brush. I do not recommend sealing the formers until installed. After all the fuse work is done, then go in with a long handled brush and paint the formers and all areas that you can reach. This helps to protect your investment, and gives the jet a clean appearance inside.

Oh, by the way, I have never dropped and broke anything in the shop. I hav'nt dropped any small screws and had them roll away to god-knows-where. I've never CA'd my finger to a part, or accidentily touch a hot soldering iron......I did it on purpose to see how hot it was.....