Rock Guard Cracked on bottom

[Wavery]

Originally Posted by DanSTL

Thanks, I’ve decided to try West GFlex 2 part epoxy with fiberglass cloth instead of 5200

If you use f/G cloth, sand the area well with 80G sand paper. Cut 3-pieces of cloth about 4" long, each overlapping the one before (set aside). Apply a thin coat of resin on the sanded surface. Put a piece of F/G cloth (the smallest one) on the sanded surface (enough to overlap the edge of the guard about 1/4"). Use a cheap paint brush to apply just enough polyester resin to wet the cloth. Lay piece #2 on top of the 1st and wet it out with that brush. Then lay the 3rd over the second. Each layer should overlap the previous buy about 1/2". Just tap the tip of the brush on the third piece to soak up some of the resin from previous layers, then just add enough resin to wet the last layer and and brush down any arrant strands. The key is to not use too much resin. Just enough to wet the cloth. The strength of the F/G is in the cloth, NOT the resin. Too much resin will weaken the patch.

Wait about 15 minutes for the layup to start to set and the resin is still a little tacky. Take a razor blade and trim off the F/G that is overhanging the edge.

Always do F/G work in temps between 65* and 80* F. Never below 60*. The warmer the temps, the shorter the dry time and the less time you have to work. 75* is ideal.

You will only need about 3oz of resin. No need for anything fancy. Bondo makes a small size of repair resin. Be sure to follow the instructions for mixing catalyst. Each type of resin is unique.

https://www.amazon.com/Fiberglass-Ad...0&sr=8-15&th=1

[DanSTL]

Thanks, great info but I applied last night and heated garage to about 55-60 (was operating under g flex min temp of 40) for a couple of hours with low of about 42 last night.

What happens to fiberglass strips I applied at that temp? Garage is 48 this am and heating now to speed up curing so I can proceed to riveting on brass strips .

[Wavery]

Originally Posted by DanSTL

Thanks, great info but I applied last night and heated garage to about 55-60 (was operating under g flex min temp of 40) for a couple of hours with low of about 42 last night.

What happens to fiberglass strips I applied at that temp? Garage is 48 this am and heating now to speed up curing so I can proceed to riveting on brass strips .

As long as the garage, product and panel were above 50* during application, it will cure. It will just take longer. 40* is pretty low but it looks like it has adhesion.

I wouldn't put any stress on it for a few days. Maybe take it in the house.

[DanSTL]

Thanks, great idea will bring it inside and I’ll delay riveting for several days ! Will post results

[DanSTL]

It’s feeling pretty dry but still has a subtle tacky feel. Hopefully over several days it will completely cure, assuming there should be no tackiness at all?

[Wavery]

Originally Posted by DanSTL

It’s feeling pretty dry but still has a subtle tacky feel. Hopefully over several days it will completely cure, assuming there should be no tackiness at all?

Epoxy resin should be sandable in 12hrs if it was kept around 70+*. Were you careful to measure part A and part B?

I doubt that the epoxy will cure at this point. If you can peel it off, I'd do so and start over. If you absolutely can't pull it off, then leave it. If it fails later, redo it then.

Epoxy resin has wax in it. As the resin cures, the wax comes to the surface. If you are going to redo the patch, be sure to wash the area of the repair with soap and water to remove the wax. Then sand well with 80G sandpaper. Try to warm up your work area and supplies to 70*.

[DanSTL]

Project completed and sharing final pics. G flex cured and just needed to be wiped/scrubbed with water (called tech line). Hopefully everything will hold - between small holes at end of cracks, rivets /brass strips and epoxy. Not perfect or pretty but just want it to hold and ready to test it. Thank you to all for pointers and help throughout!