Fibreglass: when is it dry?

[Spathodus77]

Hi all,

I'm currently having my first experience using fibreglass to effect a minor repair on the inner wing of the TVR. Enjoying it loads, but when is it dry?

The fibreglass seems to harden with the first few hours and a cursory wipe with the finger reveals that the surface is 'tack free', however if I push a little harder and wait a few seconds the resin is still slightly tacky and I can leave a finger print on the surface. I have left the wing for four days since application and it is still in the same state.

Is this normal for glass fibre? I ask because I notice that frosts sell a polyester resin that they advertise as drying tack free. This makes me think that normal glass fibre is slightly tacky when dry.

Can I paint it in this slightly tacky state?

Thanks,

Ralph.

[Justin S]

Do you mix the resin correct, as it should go off and stay off. By what you are saying there is resin that didnt mix properly, which you will not be able to do anything else with, as with heat cycles, will cause the paint to bubble and lift.

[Spathodus77]

Thanks for the response. I mixed the resin adhering to the instructions exactly. I had heard that the resin can go off (in the can before it is mixed) if it is left on the shelf for a long time. I could n't find an expiry date on the box...is this likely to be a possibility?

Thanks,

Ralph.

[CNHSS1]

was it particularly cold/ damp in the air? neither are good really for decent cure.
was it polyester or epoxy? epoxys often take longer.

id get the section warm/hot as this may help to cure but does sound as if something is amiss. bit of abodge but as its underneath a wing, paint over a coating of mixeed resin/cat and at least that should cure the tacky/soft feel. Mix it cat heavy (upper end of specified ratio) and pour into a paint roller tray (mixed resin over large surface area goes off/exotherms more slowly) so gives you a couple of minutes more to work with. If you mix in a pint pot or jug itll go solid more quickly and you'll run out of time!
if its structural and youre unhappy, grind back and do again