Fiberglass saddlebags shrink and bubbling

Anything goes in the world of fiberglass and plastic



Non-Lurker
Posts: 2
Joined: Thu Apr 21, 2016 5:28 pm

Country:
USA
PostPosted: Thu Apr 21, 2016 7:52 pm
Hi everyone....this is my first post and I will try to be as brief as possible. First off I own a small collision and restoration shop so I consider myself fairly experienced with body and paintwork but fiberglass is always a different animal. I've done a few vettes including panel replacement with no problems I also always look for new things to learn and try new ideas. Ok here's the issue. In the winter a customer brought me fiberglass saddlebags for a show bike and I straightened them out a bit after sanding with 180 and doing a little icing work then I epoxied them and spray polyed them blocked that out and 2k primer and a coat of sealer then paint. Oh and it is black... Assembled bike and he took it to Florida for a week and when he came back there was a little shrink which I expected (I don't have a baking booth). But it all wet sanded out and looks sweet but the problem area is where it looks like the bags were seamed together in the middle. There is a line in both bags same spot and the only thing I can think is that's where the were molded together and when it got in the heat with the black paint it finally cured. Now I want to re spray the bags and my questions are does anyone have any idea if I could safely bet that they are cured now. The bike has been down to Florida quite a few times since and the weather is decent up here now. There is also a bubble in one bag that I haven't seen yet and the only thing I can think is an air pocket between the gel coat and fiberglass which seems common on fiberglass parts no matter how good they claim to be built. I tried to take pics but you can't see the lines in the photo. Sorry for the long post and thanks for looking. Dan

User avatar

Board Moderator
Posts: 6672
Joined: Tue Feb 24, 2004 7:00 pm
Location: central Ohio
Country:
USA
PostPosted: Thu Apr 21, 2016 10:34 pm
Hi, Dan,
Yeah, not so much air bubble but probably the remains of trapped solvents residing in an old flash seem "pocket." Cycling of hot and cold back and forth does drive the liquid back to gas on the hot side and it has to pressurize/escape. Only thing I can think of is....opening the seams up somewhat and using liquid epoxy resin to seal the seams before moving on with the rest of the paint work. That resin would act as somewhat of a thermal barrier as well as solid barrier against any little bit of gas coming up. Hopefully the resin would also sink in and fill out any remaining voids.
Flashing seams like this are always the worst to deal with and have become much more common in kit car bodies, body styling kits, motorcycle accessories, etc. I always recommend just biting the bullet and grinding them completely open for more epoxy or compatible fiberglass.
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!



Non-Lurker
Posts: 2
Joined: Thu Apr 21, 2016 5:28 pm

Country:
USA
PostPosted: Fri Apr 22, 2016 10:23 am
Thank you for the input. I spoke to my areas Ppg rep this morning and he said basically the same thing as far as grinding it back out and doing body work on the seams. As far as the bubble that was my other thought that maybe it was from the release agent or from the resin or gel coat itself who knows.....ill have a better idea tonite when I get my hands on it and cut the bubble open and see what's up. I will update. Thanks again

Return to Fiberglass and Plastic

Who is online

Users browsing this forum: No registered users and 33 guests

cron