Corey's Goop Urethane on Polyester?

Submitted bydvanommen onThu, 07/30/2020 - 22:25

I can't find much info on this topic anywhere else online - anyone here used Corey's goop on poly skin? Only thing I can find online (and the only way I've used it in the past) is on nylon that he sells with the stuff. He does have a poly fabric available though. Can anyone weigh in on this?

The purpose for using that urethane on a polyester fabric would be for saving cost. His nylon fabric is a bit more expensive than 8 or 10 oz poly I can find in other stores.

JayBabina

Fri, 07/31/2020 - 11:38

I did do a lot of fabric research back when I built my SOF. Nylon is softer and pulls and stretches easier on to the kayak whereas Poly is a stiffer fabric. BUT, once nylon gets wet, it loosens up way more than poly. I used Poly and at the time there was a commercial SOF boat company I consulted and they only use poly for that exact reason. I found it to be true when I saw paddlers with loose skins on their boats.

I coated the bottom of my hull with epoxy in spite of everyone telling me its too stiff and the world will come to an end if you do that. It worked out great and has lasted too. The rest was coated with marine quality polyurethane from a boating store. I sanded my fabric with a fine sandpaper before coating. Before you ask, can't remember what weight fabric. If my brain kicks in and I remember the vendor I will add on to this.

daviddewitt

Fri, 07/31/2020 - 14:09

I used Cory’s goop on Jeff’s (Kudzu craft) polyester.   Although I have 40 years of fiberglassing experience building cedar strip canoes and kayaks I hated the outcome.   Maybe it was the combination of polyester and the goop, or maybe my technique (too much squeegee pressure), or maybe the temperature but I was left with a surface full of tiny bubbles.  I hated the outcome.   Save your money and stick with an oil based enamel

John VanBuren

Sat, 08/01/2020 - 06:19

I have used plain old brush on Rustoleum on a couple of poly SOF boats and I am happy with the results. So pleased in fact that should I decide to build another SOF, I would use the Rustoleum again.

John VB

Several years ago Dave Gentry started using PL Premium Polyurethane Construction Adhesive to coat his boats he skinned with polyester.  I have not heard how it worked long term but I know a lot of other people started using it and I only heard good reports.  I recall one person used it on Nylon and it stabilized it so he didn't have the stretch problem.  it may be worth contacting Dave and getting an update.  he put it on with a rubber spatula.

dvanommen

Sat, 08/01/2020 - 19:51

Thanks all for the info! I've committed to the 840 Poly skin from the skin boat store. I haven't yet landed on a coating for it, but the suggestions you all have given are good - I'll think it over and make a decision once I get the frame built. I know Jeff at KudzuCraft uses paint on his poly skins with good results, and his proof video speaks volumes. I live in Florida and will be taking this on both inland lakes/rivers and intercoastal waters, so I want to make sure it's solid. But I shouldn't be frequently running into anything that will give any serious scares with the skin.

I'm also wanting to keep the skin option on the cheaper side at least for right now as I'm building a prototype design - want to make sure it's going to be a good boat before I sink money into the high quality stuff! I feel good about the design, but it's always good to be on the safe side!

Brian Nystrom

Mon, 08/03/2020 - 08:00

If you don't like the high-gloss look (I don't), Zar Exterior Satin Oil-based Polyurethane works really well, is easy to apply and it's quite durable. If you want to tint it, you can add artist's oil paint to it to achieve almost any color. I've used it on both polyester  - which takes almost any finish very nicely - and Nylon, though I don't use Nylon anymore because it's more finicky about finishes that will stick to it and it loosens when it gets wet. BTW, the latter issue is not because it stretches, it's because it absorbs moisture and expands, then shrinks again when it dries.

I have used Zar after being recommended by others, it does seem durable and easy to apply. It is a moisture cure finish, when adding colorant only mix what you think you will use at that time.  I mixed a quart and used maybe half, the next day when I opened the container it had hardened to a gel.  I had ordered two quarts so I was not at a standstill waiting for more to be shipped. Yesterday I paddled the first kayak I built, it's over ten years old has seen lots of use year round for the first three years.  Lives outside and still has the original skin,  8oz. nylon and goop. One of my kayaking friends built a very nice Greenland kayak with poly skin with porch and deck paint, looks great.

I was mistaken in my comment above about Zar being a moisture cure, the product that I had used was Dura Tuff by Famowood. Sorry for the misinformation.................George