Epoxy Thickness

[LP]

I'm about ready to flip over the 18' mahogany runabout that I'm building. Everything is glassed and the side weave is filled. I'm filling the bottom weave and fairing it with "microlight." I've never faired with the stuff before, so I'm not sure how epoxy coating it needs once the fairing process is complete. Common sense says two coats. Any dissidents?

[jfblouin]

Very nice boat !!!

What is the weight of fiberglass on the hull ?

[LP]

It's 10 oz. weave on the bottom and 6 oz. on the sides and transom.

[wdnboatbuilder]

okay i can only guess that you are using west system? micro lite is a very easy sanding filler for epoxy but also you have to keep in mind that if it is easy to sand then it is also very soft, meaning that it will easily show signs of dents and dings. west makes a filler that is a little harder and personally that is what i would use. to cut down on that tough sanding fill only the holes with the filler then fair then roll as many coats as you can in one day (atleast 3) and fair the next day with a file board, if you have experience you could use an air file but i would not unless you have experience.

[LP]

Airfile?

[gonzo]

Microlight and other hollow sphere fillers are not supposed to be used below the waterline. They absorb water and can cause problems. If you cover it with two coats of pure epoxy it may be OK. WEST recomends to fill the weave with pure epoxy or a bit thickened with silica or grafite.

[lewisboats]

Originally Posted by gonzo

Microlight and other hollow sphere fillers are not supposed to be used below the waterline. They absorb water and can cause problems. If you cover it with two coats of pure epoxy it may be OK. WEST recomends to fill the weave with pure epoxy or a bit thickened with silica or grafite.

Personally I'm cheap...I have always had success with just wood flour. Baby powder (talc) works too, and smells nice when you sand it, but it is a bit heavy.

Re-reading the original post...you have already filled the weave and are wondering how thick you should build up the coats AFTER you have filled. I would say that a couple of coats of epoxy should be sufficient to provide a decent barrier.

Steve

[chandler]

Hi Learpilot
Are you using west system? Probably too late but I much prefer MAS if for no other reason than it smells better and is a little less expensive. They also have a fairing filler which is very user friendly, ie. easy to sand. 2 or 3 coats of epoxy over anything should keep the moisture out. Nice hull!

[LP]

Hi Chandler,

Look at this link


http://www.oneoceankayaks.com/Epoxtest.htm


MAS didn't to well in this guys exposure test. Granted, it deteriorated in the unprotected state.

The price comparisons that I've done don't put MAS http://www.masepoxies.com/pricelist/...lpricelist.pdfthat far down the list. Do you have a different source?

RAKA at http://www.raka.com/EpoxyPricing.html is around half the price of MAS and faired well in the exposure test.

Still cheaper is USComposites at http://www.uscomposites.com/epoxy.html at 20-25% below RAKA. Unfortunately this product was not evaluated in this individual's exposure test.

Realizing that this exposure test is vary limited in scope. Ease of application, odor, strength, etc., etc. were not discussed, but there is some discussion as to coating thickness and the effects on poorly coated and exposed epoxy.

======Actually, there is other discussion as to various properties of thesr products.=======

Interesting note about using vinegar for clean-up. Has anybody done this?

Regards,

[chandler]

Hi Lear,
My source would be Hamilton Marine, I suppose it would be cheaper to go directly to the source in this day and age . Raka really 1/2 the price? Someting to think about.
What's their mix? Another thing about MAS that I like is it's 2 to 1, no need for messy pumps that usually last for 3/4 of the epoxie you have.
Obviously the most important feature after cost is the blush factor, which west system has always ranked very low, can't imagine the strength factor changes much from brand to brand.
Chandler
Oh, and yeah I have tried vinegar, I realize you're not supposed to get the goo on your skin, but vinegar doesn't work that well. Only thing I've found useful is gojo if the glue is really fresh or acetone or one of those equally toxic solvent.

[gonzo]

Epoxy laminating resing should not be exposed to the sun. That test means nothing except that the kayak builder didn't read the instructions for the material he is using.

[LP]

Yes, we all know epoxy needs UV protection and every boat that we build is perfect in every way. But, should the UV barrier fail, would it be nice to know that the epoxy will stand up until such a time that it could be repaired. It's everybody's personal choice to use the information on this forum. Personally, I think the test makes several important points.

1) UV degradation is real.
2) Not all epoxies are equal when in comes to UV sensitivity.
3) Varnish with UV inhibiters work.
4) Higher price doesn't mean better product.

[FAST FRED]

"Airfile?"

Your local auto paint store will have an air powered "Jitterbug" and many other air fairing systems .

Unfortunatly cars are small and mostly rounded .

For real fairing a long ( 3, 4 or 5ft )flexable 3/8 or 1/2 inch ply board 4 to 6 inches wide with plane handles installed is best for long straight areas. It takes 2 to use the long board.

Best "sandpaper" comes from the floor refinishing industry.
In either sheets or rolls the surface is silicone , rather than softer material.

The very coarse stuff (16 or 20 grit) worked lightly is better than the fine grit as it clogs much less.

FAST FRED

[Gilbert]

For removing epoxy from my skin I have paper sacks full of band saw dust sitting around the area and "wash" my hands in the sawdust. It does an excellent job of removing the epoxy. I do it right away when contact occurs; I don't wait. The epoxy seems to have a preference for sticking to the sawdust over sticking to me. I also "wash" my disposable gloves before removing them which reduces the amount of sticky stuff that seems to end up everywhere if I don't.

[chandler]

Gilbert,
I've used that method for years. It really does work, though not very scientific, and you know how scientific the readers in here are, or maybe you don't.