Need help with shrink

[Bradley Adkins]

Hey I’m having trouble with gel coat repair patches shrinking I suspect it’s due to too much heat from buffing but I figured I’d ask someone more familiar with this stuff than I. I catalyze correctly and wait a nearly 24 hours before I sand and after I buff it to a polished shine I notice it always sucks in a little I’m away from work currently but I will get pictures posted tomorrow any help or advice is appreciated
Thanks
Brad

 

[gonzo]

That is barely enough time for the solvents to evaporate. If you want to speed up the cure, use a heat lamp.

 

[antonkov]

I just mentioned the shrinking issue in another thread. Depending on the type of polyester you are looking at 2% or more of linear shrinkage (5-13% volumetric). Seems like everybody using a common, basic kind of PE is dealing with it. Among the solutions is to compensate for it beforehand or to use special (i.e. more costly) resins or additives.

 

[gonzo]

I usually lay a thicker than necessary coat of gelcoat and sand it down after. The other solution is to finish with a gelcoat/Duracote mix and spray the last coat on.

 

[Bradley Adkins]

I believe we use a vinyl ester gelcoat I always apply it thicker than needed and sand down I’m going to try the heat lamp thanks for the advice.