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Best way to get a good finish on epoxy

Posted: Fri Jan 19, 2007 11:33 pm
by Jimneybob
I'm nearly finished building my first ply kiteboard and am just in the process of sealing it with West System epoxy. Problem is though that its mid winter and about 5oC outside so epoxy is acting like thick honey. At the moment I'm using a grouting speader to give a fairly even coating and then "tipping of" with a brush so that I get a reasonable finish. The Epoxy is starting to cure though before I'm happy with the finish so was wondering if there were any tricks that I am missing out on? What's the best method of application and how thick should I really be applying it?
Tips would be helpful, if not for this board then for my next.
Cheers :thumb: ,

Epoxy surface finishing tips

Posted: Mon Jan 22, 2007 2:31 pm
by FNG
West makes a thinner that can be used if you want to flow the board however it really retards the curing.
You can use a heat gun to do a hot coat but epoxy will not flow like the thinner ester resins that outgas.
One of the easier things to do for onesy-twosy board production is use a lightweight poly sheet in the 2 - 4 mil range. If you have a heat gun, hang the poly and gently warm it until any creases and wrinkles are gone. This will be important in colder shops where creases like to remain in your cover release sheets as the temperature goes down.
After sanding your surface down as smooth and fine as you can get or want it - 220 grit is where most orbital marks start to fade - wipe your surface to remove any dust or other matter.
With a smooth poly release sheet ready, roll out a uniform coat of epoxy over the surface with a foam roller - 3mm will quickly apply sufficient resin while keeping the loading down. Lay the plastic over the work and using a spreader that has smooth edges that won't snag the poly, work the epoxy from the middle outwards. Side lighting will indicate any resin bubbles and air bubbles will show up clearly through the plastic. Wipe the excess resin from the edges and wrap any major contour changes with a piece of tape to keep the poly sheet from rolling up as the resin cures.
When done well, the cured surface will be absolutely smooth,uniform, glossy, wrinkle, bubble and impurity free leaving a small meniscus bead of resin around the edges that can be removed with one light pass of a blade on edge. The end result is a professional manufacturer grade polished finish.
If you take care of your poly release sheet, it will remain in great shape for many boards. If you will be doing many boards and can manage care for it, go up in the thickness and quality of your release sheet to the thickest mill that still holds the contours of your boards with the surface tension created by your resin.

Posted: Thu Jan 25, 2007 11:20 pm
by TomW
After the PBT brothers ripped me off and i never got the PBT sheet i ordered and paid for, i now need to do this too.

What do you mean with "a mil". I´ve never understood this. is this UK english for a millimeter ? or do you mean one thousands of an inch?

So the idea is to coat the board, put a ply sheet over and squeegee it out. Do you press out the epoxy with the squeegee?

sounds like it might work.


Posted: Thu Jan 25, 2007 11:56 pm
by FNG
.001" is a mil.
Yup. Lay down your epoxy then the plastic and smooth your epoxy out towards the edges.
Use a semi flexible/hard plastic scraper that slides over the poly with a drag.
It is better to put down a couple of thin coats sanding between as they cure.

Posted: Fri Feb 02, 2007 6:37 pm
by Jimneybob
Cheers for the ideas but couldn't wait to get my first board finished so will have to look for the poly sheet for using on my next board. Quite happy with the way this one has turned out anyway as it works and that's about all I was hoping for. Just waiting for the wind now.......

When you say "poly" though, exactly which polymer are you refering too, and if anyone knows, where would be best to get a small quantity from in the UK?

Posted: Fri Feb 02, 2007 8:09 pm
by FNG
Not talking about applying a polyethylene surface, talking about using polyethylene plastic sheet as a release layer to smooth out the epoxy which was the original question wasn't it?

Posted: Fri Feb 02, 2007 8:45 pm
by Jimneybob
Yeah, FNG. That's what I meant.
Sorry, I'm used to working with "poly"-saccharides in my work and the amount of times that people start talking about "poly"-this and "poly"-that it often gets confusing. People often just say "poly" for any kind of polymer at work so I just wanted to make sure that the "poly" everyone was talking about was polyethylene.

I was using some poly sheet when I did my laminating to stop the board sticking to my rocker table but I didn't really take any care of it and now its not really any use to create a smooth finish. I'd ahve taken more care of it if I'd have thought of this before.

Posted: Sat Feb 03, 2007 11:37 am
by crabman inserts ,poly etc

Posted: Sat Feb 03, 2007 12:41 pm
by Jimneybob

Here' a couple of piccies of my first finished ply board anyway. Just finished it properly yesterday after testing last weekend and modding this week. Thought I'd stick a couple of pictures on anyway as I like seeing other people's so thought I'd show mine. :thumb:

Posted: Tue Feb 13, 2007 1:44 pm
by munteruk
Looks pretty good for a first effort. Quite a square outline!

Have fun with it. You'll be building your next one before you know it...
I'm on number 6 now.