Fiberglass Repair Help

[CCI]

I think I got the resin to catalyst ratio about right, the resin on the glass mat hardened up fine but the resin around the mat on the original piece is still tacky after five hours. Heat gun seems to help a little but not much.

What's the next step?

 

[Owen Lucas]

I have never done this type of work so take this with a grain of salt. How about letting it air out? Are there any instructions of a customer service support number?

 

[Dave9]

Wait longer and see if it hardens more. How long was it supposed to take? Yes a little heat will accelerate the process which is why (unless you didn't mix it well enough) the thicker portion self-heating more should harden faster.

 

[Wrenchturner44]

I need a little more information to understand what you did. Are you using standard polyester resin and fiberglass mat with acetone based catalyst? Or are you using something like the West system? Polyester resins are pretty lenient on mixing catalyst. You have to be close but not exact. You also have to thoroughly mix the resin and catalyst. Last question, what are you making or repairing?

 

[wpod]

I need a little more information to understand what you did. Are you using standard polyester resin and fiberglass mat with acetone based catalyst? Or are you using something like the West system? Polyester resins are pretty lenient on mixing catalyst. You have to be close but not exact. You also have to thoroughly mix the resin and catalyst. Last question, what are you making or repairing?

The west system is the way to go for a super strong job.

 

[CCI]

I need a little more information to understand what you did. Are you using standard polyester resin and fiberglass mat with acetone based catalyst? Or are you using something like the West system? Polyester resins are pretty lenient on mixing catalyst. You have to be close but not exact. You also have to thoroughly mix the resin and catalyst. Last question, what are you making or repairing?

Standard resin and mat, it's a kit from an auto parts store.

I might not have mixed it well enough, but it hardened up great over the mat, just stayed tacky at the edges.

Fiberglass saddlebag repair.

Heat gun seems to have helped, a few rounds of heating and then being left to cool, NCIR thermometer said surface temperature of 145 to 165 degrees.

 

[Wrenchturner44]

Thank yiou for providing more information. Another thing you can do is put it out in the sun. Sometimes the UV will react to make resin harden faster. I think your assumption of not mixing it thoroughly is probably what happened to cause the issue.

 

[wrcsixeight]

ive had polyester resin refuse to cure atop epoxy, as well as having it cure, but refuse to bond.

both polyester and epoxy generate their own heat, and thinner applications take far longer to get tack free.

Generally the 'fiberglass resin' in parts store containers is a sanding resin vs laminating. it has a wax that rises to surface, encaPsulating the resin allowing it to ure tack free. This wax must be removed before any secondary bonding is attempted.
With cured Laminating resin, the hard but still tacky resin will accept another layer with no prep.

if the resin was worked with a brush after the wax rose and wax was effectively removed, then it will remain tacky forever after. you'll need to remove all the remaining wax, and brush on another layer and FFS, dont overwork it. Once it starts gelling, stop, walk away.
The sandpaper will clog up quickly when prepping for another layer.

Epoxy is a different animal.
West systems has great brand recognition, but is my least favorite to work with.

 

[thastinger]

I think I got the resin to catalyst ratio about right, the resin on the glass mat hardened up fine but the resin around the mat on the original piece is still tacky after five hours. Heat gun seems to help a little but not much.

What's the next step?

Put it in the sun and wait until tomorrow

 

[CCI]

Thank you all for the help.

 

[Donald]

Thorough mixing is key.

I built a Luger fiberglass kit boat in the 1970s. You screwed together the sections and bonded with fiberglass. Making a fiberglass boat in more than two sections (hull and deck) was a dumb idea. The Luger boat was 5 sections.

Glad I have a nice Chaparral boat now.