Talk Composites - The Forum for Advanced Composites

Gelcoat not fully hardened

http://www.talkcomposites.com/Topic7297.aspx

By LaxFriedrichs - 7/31/2013 6:01:27 PM

I started a second mould (Unimould system) a few days ago, and the gelcoat is not hardening as it did the first time.

The second coat's surface area seems to be 95+% hardened, however there are little patches where it hasn't. In these places the gelcoat is no longer a shiny 'gooey' fluid, it's matte and some what pliable.  

Is there any way of recovering this?

Tomorrow is going to peak at 27 Deg C, could I put it in the sun and use the exotherm of the coupling coat and tooling resin coat to harden it?
By LaxFriedrichs - 8/5/2013 4:12:54 PM

UPDATE:

I pulled the mould at the weekend. It looked like the 1st gelcoat layer had not fully hardened, due to the alligatoring and bubble like cavities.

Fortunately, the distortion on the surface wasn't terribly deep and was not over all of it. Strangely, any surface in contact with the easy release tape was perfect.

So I've sanded down the peaks, and filled the deeper cavities with gelcoat. Again it's fortunate that the tolerance on this part is not a great issue...

Below Figure show two moulds taken from two different sides of my pattern. Bottom image is a reflection for comparison purposes.
TOP - Mould #1 - just needed some finer grades of wet & dry to finish.
BOTTOM - Mould #2 - Rough sand of peaks, and cavities are gelcoated over. Much work to be done!

http://dl.dropboxusercontent.com/s/7erenhrhzs1u6js/comparison.jpg