+x

 

Fasta - 5/7/2019 1:51:57 PM

+x

 

Coldever - 5/7/2019 11:47:12 AM

+x

 

oekmont - 5/7/2019 9:46:50 AM

This seems to me like "alligatoring". This can happen when your poly/vinylestet gelcoat is applied too thin. This results in too much styrene evaporating relatively. And because the styrene is a reactive component of the resin, the resin does not fully cure. This is how gelcoat stays reactive on the surface, but if the layer is too thin, the whole layer does not cure properly. The next layer of resin the attacks the semi cured resin, resulting in these wormy imperfections.
To avoid this, use a fine brush, as brushmarks are the easiest attacking spots for alligatoring. And then apply the gelcoat a little thicker. And as even as possible. Best way would be a gelcoat spray gun.

Thanks, that makes sense as most of the "alligators" are located on the mold flange where I probably didn't pay that much attention to the brush marks and coating thickness.

Definitely alligatoring, maybe a combination of a few things.
Gelcoat too thin near the edges
Vinylester is very aggressive compared to polyester so you need to be sure the gelcoat is thick and the resin gels fast.
Melamine board releases very easliy compared to other materials, I actually make a point of avoiding melamine for flanges etc as it can release too easily with resin shrinkage.

+x

 

Coldever - 5/7/2019 11:47:12 AM

+x

 

oekmont - 5/7/2019 9:46:50 AM

This seems to me like "alligatoring". This can happen when your poly/vinylestet gelcoat is applied too thin. This results in too much styrene evaporating relatively. And because the styrene is a reactive component of the resin, the resin does not fully cure. This is how gelcoat stays reactive on the surface, but if the layer is too thin, the whole layer does not cure properly. The next layer of resin the attacks the semi cured resin, resulting in these wormy imperfections.
To avoid this, use a fine brush, as brushmarks are the easiest attacking spots for alligatoring. And then apply the gelcoat a little thicker. And as even as possible. Best way would be a gelcoat spray gun.

Thanks, that makes sense as most of the "alligators" are located on the mold flange where I probably didn't pay that much attention to the brush marks and coating thickness.

+x

 

oekmont - 5/7/2019 9:46:50 AM

This seems to me like "alligatoring". This can happen when your poly/vinylestet gelcoat is applied too thin. This results in too much styrene evaporating relatively. And because the styrene is a reactive component of the resin, the resin does not fully cure. This is how gelcoat stays reactive on the surface, but if the layer is too thin, the whole layer does not cure properly. The next layer of resin the attacks the semi cured resin, resulting in these wormy imperfections.
To avoid this, use a fine brush, as brushmarks are the easiest attacking spots for alligatoring. And then apply the gelcoat a little thicker. And as even as possible. Best way would be a gelcoat spray gun.