How much time can you have between gelcoat layers?

[ktm_2000]

Hi All,

The ideal I am trying to hit is 4 layers rolled on, mix and roll on in @20 min, let cure for 30 min, repeat 3x with the last coat being waxed gelcoat where as coats 1-3 are no wax added gelcoat. To do it all right it takes me a good 4hrs.

I've been getting jammed up pretty bad with work and am getting smaller windows of time to make progress on my project and am wondering what I can get away with and what I can't.

If I were to start late and just lay down 2 coats tonight, could I pick up tomorrow night and do the other 2 coats or would I need to sand?

thanks in advance for your advice.

[ktm_2000]

without knowing one way or another, I did the 4 coats as a group with the last 2 coats in the dark with some 500 watt halogens for light and a bunch of bug spray to keep the mosquitoes at bay.

[mike ohlstein]

Hot and humid as it is you probably have a few days, but the basic rule is 24 hours for a chemical polyester bond without any further prep. Epoxy is much different, but with polyester you have time.

Gelcoat, glass..... samey same.

[ktm_2000]

Mike - My plan for the deck is as follows:

Gelcoat Deck (Round 1)
Gelcoat Deck (Round 2)
Layout Non-Skid Pattern with Tape
Gelcoat Deck with Non-skid (Round 3)
Remove Non skid pattern tape
Finish Gelcoat Deck (Round 4)

If I did coats 1&2 and left it overnight and then taped off the deck for non-skid then did the non-skid and waxed top coat the next day. I was planning on mixing the non-skid compound with the gelcoat for coat #3. I am assuming that taping off the deck is going to take me a fair amount of time if I am going to make nice radius curves in the corners. I was thinking that I would want the 2 base coats to be well cured but still open to take further layers during that operation.

Here's a pic after the first coat last night
https://photos.app.goo.gl/3hRRYdHHmwpdRrd49

[mike ohlstein]

What you're doing will work fine. I wouldn't wait longer than three days between coats without sanding, but inside of three days is fine.

Boat builders spray plenty of polyester on Fridays and don't apply the next layup until Monday.