Repair of hairline cracks in gelcoat

[rwidman]

Originally Posted by Emmalina

Used to use a product called Capt Tolleys creeping crack cure. Not sure if it is still on the market

It is available at amazon.com

Creeping Crack Cure® remarkable penetrating waterproof sealant, covers the smallest hairline cracks
Leaves a clear, almost invisible seal
Use for window casings & sills, plumbing joints & more
No mixing - simply squeeze and go! 2fl. oz. each
Works on wood, brick, tile, ceramics, plastics, fiberglass, concrete and more

Usage Indoor applications

It seems to be more for buildings than boats.

[Terra Nova]

It's not for gelcoat repairs.

[DefinitelyMe]

Originally Posted by Emmalina

Are you sure fiberglass absorbs water ! You might find polyester or GRP does but fiberglass !!!
The reason boats are made out of GRP (Polyester) is cost not practicality Fiberglass is 3 times the price. Having made many fuel tanks and holding tanks out of fiberglass can't say the substrate has absorbed anything !

I'm struggling to understand this....... Fibreglass is fibreglass (i.e. literally fibres of glass). GRP stands for 'glass reinforced plastic' which can be polyester, epoxy, or any of a number of less-common resins that are absorbed into a mat of glass fibres and then harden to form a plastic material which is reinforced by those glass fibres.

[Terra Nova]

Epoxy is a vapor barrier. Polyester is not.

[COLINFLTENG]

I was advice to cover cracks with decal vinyl