What is used to fill in the deep scratches in fiberglass in order to get it ready for paint. Bondo, epoxy, what. I only want to do this once, and want to come out with a good long lasting job. Therefore I do not want to use the wrong product that my just vibrate out. This is for saddle bags on motorcycles.

And when priming fiberglass is their a special type primer used or is it basically the same as metal priming.

Thanks

 

I've used fiberglass in automotive applications but don't know if there would need to be any extra precautions for your application. Generally, bondo is used to finish the repair [lightly sand the fiberglass first]. Another coat of fiberglass/mat can be applied before the bondo if extra strenght is needed.

Most primers will adhere well to fiberglass/bondo so I would let whatever topcoat is to be used, dictate which primer to use.

 

small scratches can be filled with bondo, but I would prefer fiberglass resin. it will bond to the glass and become part of the fender/door, etc.. sand first and clean with a good fiberglass cleaning agent to remove dirt and fingerprints.

the primer needs to have a flex agent in it if it is a moveable part that will flex in use.