JEM Watercraft

How long should epoxy cure before the varnish is applied?
Ron

Check with the epoxy manufacturer. A lot of builders will wait at least a couple weeks.

In the sun or in the shade while waiting?
Ron

I would keep it in the shade. I had one I built that I left out in the summer sun just a couple days without varnish and it damaged the boat in a small spot. It made the weave of the cloth turn white and become visible. Luckily it was just in a small spot.

tx river rat wrote:How long should epoxy cure before the varnish is applied?
Ron

72 hours at the minimum..........I like to go 30 days before varnishing....

Look at it this way ... You use the boat while the epoxy cures all the way , it gets scratched and some water marks on it while using it...... BIG DEAL , You got to use it and see how it handles.......

Then after that you lightly sand it ( you would do this no matter if it set in the shop or was used ) to remove any contamination , scratches and other stuff before varnishing.

You have it cleaned , lightly sanded and VARNISHED........ A new boat when varnished after having some fun with it.......

They say it takes the epoxy a total of 30 days to really set up and get to be itself....... Let it grow up before varnishing it.

If you want to permanently protect the epoxy, and if you can break with boatbuilding tradition, consider taking the boat to a local autobody shop to have them spray on automobile clearcoat. The stuff flash-dries in about 15 minutes, so they can spray on 3-4 coats in an hour. If you don't want a gloss finish, the shop can add some flattener to the clearcoat so you'll end up with a satin finish.

Hey, I like the sensual pleasure of brushing on good spar varnish then wet-sanding between coats to finally end up with 5 coats. And it's sure the traditional coating for clear-finished wood boats, but...

You'll spend five or more days doing the spar varnish coats, and end up with only a 4-5 mil film thickness. Three coats of auto clearcoat will spray on in about an hour and give a 10-15 mil thickness.

Spar varnish is intentionally soft and flexible so future dings can be easily be repaired. Auto clearcoat is incredibly hard yet very flexible. It is however, difficult to fix dings in the finish in a home shop without a sprayer.

The spar varnish will need to be renewed every 2-3 years. Auto clearcoat seems to be permanent.

Spar varnish is pretty good at blocking UV rays to prevent damage to the epoxy undercoat—as long as the film thickness is maintained. Auto clearcoat is superlative forever as a UV block without having to renew the finish each few years. When's the last time you saw a car with modern base coat/ clearcoat finish with faded paint?

Overall cost of top-quality spar varnish is about the same as good Pittsburgh Paint & Glass (PPG) clearcoat, especially if the body shop is spraying a car with cearcoat the same day you bring in your boat.

I have a test panel of glued up cherry strips, fiberglass- and epoxy-covered, then sprayed with three coats of an off brand of clearcoat (cheaper than the good PPG stuff). It's been in direct sun now 24/7/365 for four years. Still looks like the day it got sprayed. The panel is the tailgate on my utility trailer that gets constant abuse, and there's hardly a scratch showing.

For me, sprayed clearcoat to protect my cedarstip canoes is a no-brainer.

I talked to the Tech Rep at USComposites last Monday and he said in the summer that you could varnish after 48 hrs. The epoxy would not be cured but would continue to cure under the varnish.

I intend to use 2 pak super gloss on my Sabalo. I have tested a sample and it is hard as ceramic. I couldn't scratch it with a key or coin. (Well, I could scratch it but only just). It can be sprayed or brushed on, but I intend to roll it on, which gives a nice 'orange peel' finish that is still high gloss. They say to leave the epoxy for only 7 days before painting, because it is a similar compound to the paint. The whole coating will continue to cure for up to 30 more days.