Body shop experts, I need your help

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Body shop experts, I need your help

June 25, 2013, 03:59:37 PM

I just started doing body work again after a ten year break. My first project is a semi with a busted fiberglass fender unfortunately. For whatever reason I can not get the fiberglass filler to stick to the fiberglass fender, it is sticking to the paint however.

Fiberglass never was something I worked with much ( I was a technician at a Chevy/Cadillac dealership). I'm completely confused as to why it is sticking to the paint but not the fiberglass fender, I've prepped them both the same so I must be missing something......

Thanks in advance for your help.

Body shop experts, I need your help

Reply #1 – June 25, 2013, 04:16:02 PM

What kind of 'glass are you using? The mat resin and hardener, that bondo glass in a can? Try widening the crack a touch use a good tape on the back side and fill it in nicely.

Edit totally didnt see the screwdriver thought it was a crack.
use a little heavier grit sandpaper for a better adhesion

Body shop experts, I need your help

Reply #2 – June 25, 2013, 04:31:41 PM

Product type would be helpful. Looks like fibre hair in a can to me, and looks like your doing things right. There may have been a large air pocket there, happens with fibre hair. 36 grit, blow everything clean, mix very well, reapply and let cure longer before sanding. Also 3M 8115 metal bond with pulled apart fiberglass mat added works very well for repairing fiberglass.

Body shop experts, I need your help

Reply #3 – June 25, 2013, 05:46:54 PM

It's short hair in a can, I don't know the brand but it did come from E&M.

I had initially roughed the entire area with 36 grit.

Body shop experts, I need your help

Reply #4 – August 14, 2013, 10:22:16 AM

I finally figured out what happened.

Freightliner hoods are made from SMC. Which is similar to fiberglass but filler epoxies will not stick to it.

The next struggle will be trying to find a reasonable priced filler that will work with SMC.

Thanks to everyone for the input.

Body shop experts, I need your help

Reply #5 – August 14, 2013, 11:18:42 AM

Look into the UPOL brand products. I have UP7061, Stronghold, High density filler for the Repair of most Plastics including SMC and Fiber glass. It's good stuff :D easy to work with. I would also use the bumper repair screen like stuff (can't remember exact name) :( and I (like bodyman suggested) use some pulled apart fiberglass mat mixed in (of course before adding hardner;))
Hope that helps a little