Plain speak; liquid resin sprayed in the mold to produce a smooth exterior uniform finish. Objective is for the part to be ready for primer, paint (or fabric finish) to cut cost of prep work down.
Wikipedia: Gelcoat is a material used to provide a high-quality finish on the visible surface of a fibre-reinforced composite material. The most common gelcoats are based on epoxy or unsaturated polyester resin chemistry. Gelcoats are modified resins which are applied to moulds in the liquid state. They are cured to form crosslinked polymers and are subsequently backed with composite polymer matrices, often mixtures of polyester resin and fiberglass or epoxy resin with glass.
The manufactured component, when sufficiently cured and removed from the mold, presents the gelcoated surface. This is usually pigmented to provide a coloured, glossy surface which improves the aesthetic appearance of the article, such as a counter made with cultured marble.
Maybe if this thread had been in the Classified section I would have found it (I had someone send me a link knowing I had been looking for a hardtop).
I've been posting in the Midwest, Michigan, and Calssified section for months now looking for a hard top for racing season. I wanted to borrow one, to get it inspected, so if it was cleared I'd purchase one. Racing season ended, for me, last week.
Also, the LeMans style has had a price reduction. A new top from Smoothline is $999 now.
Wish it was still race season, but I can't spend the money on the top and wait and hope to see it get inspected. Best of luck on the sale... I want a hard top, if I can get on the track for our test-n-tune sessions with it.