Epoxy/Adhesives

I hear everyone saying that you need to use epoxy on wooden boats, but what kind/brand is good. I have researched it alot and I have found that there are all different products with the name "Epoxy". I have seen epoxy adhesives and epoxy coatings, with all different ratings and dry times. So what should a novice boat builder use that won't cost a fortune? Also, with exterior plywood is using a waterproof sealer necessary or could oil based paint work too? I am just building something that floats and that I can fish from. I don't want to spend to much on this. Any help with this would be great.

 

Epoxy formulators produce resins that all are very similar in physical properties.

Epoxy is a two part mixture, when mixed produces a resin that can be used bond, glue, coat, saturate, etc. It's mix with "reinforcements", which include cloth and other fabrics, powders, even coloring agents. Lots of stuff can be mixed or used with epoxy.

What it does for wood is seal it. It keeps moisture from getting in and starting rot. If used with a fabric, then abrasion resistance is dramatically improved and well as water proofing. Used as a glue it can bond most anything very well, mixed with specific materials it can be used a fairing compound (think body putty) to smooth out surface defects.

Do you need it for your floats, no. Do you want to use it, probably. Why? Well, it will dramatically increase the life expectancy of the floats and decrease the amount of maintenance you'll have to perform.

You could use paint, but in a few years, the wood will be soaked with oil, scum, water, etc. Little microscopic beasties will have made a home inside the wood and they bring the in-laws with them, to feast on your floats.

If you don't need long service for your project, then skip the epoxy. If you'd like something that will last, then log onto www.westsystem.com and www.systemthree.com and download their "user's guide", which will nurse you through the different products, fillers, techniques, etc.

There are several formulators of epoxy (I'm thinking about becoming one) and many of these have much lower prices then the major suppliers.

 

Thanks PAR for those web sites, they are very informative.

 

This little company Fasco down in Hialeah have been in the formulating business for many years. Their products are good and reasonably priced and they will provide tech data on request. They make a very good varnish also.

Jimbo

 

you dont need epoxy

 

So what are you suggesting he use instead of epoxy? Polyester resin perhaps? If so, that would certainly be poor advice that I would hope the original poster knows enough to to ignore.

Jimbo

 

use wood, it used to be that we sometimes could not see the wood for the trees, now we cant see the wood for the epoxy

 

Pete
jazman mentioned plywood! I do´nt see any sensible substitution of epoxy in this case.

Regards
Richard

 

Are most epoxys clear or colored? I know that PAR said that some could have coloring agents added, so does that mean that the rest are clear or just a standard color. If I use epoxy I would like to keep the wood look, so clear is what I would want to use.

 

All (liquid) epoxy resins start out somewhere between nearly clear light amber, to a medium amber, but always translucent. The solid (at room temperature) epoxy resins are sometimes quite dark in color, but they are of no interest to you. Be advised that most epoxies are NOT very UV resistant, so would need to be over-coated to provide UV resistance. An opaque coating is best, but since that is at odds with your goal of retaining the beauty of bare wood, a high-quality clear urethane could work also. The high-end stuff always has a significant amount of UV inhibiting chemical. These chemicals can cost nearly $1000 per gallon, so typically only the best quality clears will have a quantity sufficient to protect your epoxy from UV degradation.

Jimbo

 

Urathane is a dust magnet
not sure why but it always ends up pocked with dust particles
Im a Mcluckies fan
man oh war clear with UV protection
never used it over epoxy but good old fashioned varnish sure makes trim look fantastic and
my favorite part
its not plastic so it sands easily
try sanding urethane and you will get my drift fast on that score
no mater what you do that Urathane will only last so long before it yellows
when it does and your ready to refinish it
good luck
right about then you may just be wishing you had tried the varnish

use what ever glue the general consensus suggests ( my experience with glue is limited ) but when it comes to finish go with ease of application and easy of maintenance

yup
poly lasts longer
but its a nightmare in almost every other regards

best of luck and have fun with it
cheers
B

 

Just to make that a bit clear, not to contradict.

Epoxy resin is not UV resistant! Not only "not very", it immediately starts to depolymerize after curing when exposed to sunrays! You MUST add a sufficient UV protecting varnish on top of your surface. That maybe the stuff of your choice as long as it is declared to be "UV protecting" and not "UV resistant",`cos the latter means only that the varnish gets not destroyed (but the Epoxy underneath will).
And there ary several crystal clear resins on the market, but usually you do´nt need them, most resins are "honey" coloured transparent and your woodwork (and every fault) are appearing brilliant with a standard resin.
Regards
Richard

 

Again, it's not fair to throw the 'All' blanket on epoxy WRT the lack of UV resistance. There are some newer resins out since the late 80's (the Epon 8000 series) that are highly UV stable. I don't know if any of the usual suspects are formulating with this series (I doubt it) as you can bet they cost more than plain ol' BPA resin.

But since the poster is doing a 'one off' project, he can certainly source some of this, if he tries.

I looked into this issue back when I was going to do a carbon mast business, and some customers wanted to have a bare mast to show the pretty carbon fiber weave. Shell's people (Epon was Shell resin's brand back then) assured me that the 8000 series would hold up to UV just fine. These were formulated with the intention of outdoor use mainly as tile and concrete grout and clear stone adhesive (you've probably never seen that in Germany; it's mostly a Florida thing) where they would be exposed to sun for decades and expected to withstand.

The clear urethanes with the UV inhibiting additives actually filter out the UV, so that little reaches the substrate below. This is most helpful in the coating business, where base/clear systems are very common. Whenever you see a base/clear installation where the clear has begun to 'flake off', what you are actually witnessing is the failure of the base coating, due to inadequate UV inhibitor in the clear coat, which then allows the clear to slough off. Clears are formulated to prevent this, but as with many other things, you get what you pay for. The cheaper clears are designed to only allow the coating to last a few years.

I can clearly (pun ) remember doing a restoration paint job on a 1970 Mercedes-Benz 450 SLC back in 1990. The ORIGINAL base/clear finish was still intact with no flaking, and fair gloss which responded to polishing, despite being seldom garaged in 20 years (a family car; I knew its history) no doubt due to the fact that Daimler spared no expense on that clear coat.

Jimbo

 

I did not even think about advanced EP formulations because it was clearly mentioned jazman did not want to spend much on it. Even I do´nt use them due to pricing. And the few percent of clear coating are not soo much on my boats as you can see in my gallery. But we use highest quality of PU varnish.
Regards
Richard

 

There are alternatives to epoxy but they are not as good. Epoxy is great both as an adhesive and as a protective coating. unlike most glues it is gap-filling. When used as a coating in conjunction with glass cloth or other fabric it adds considerably to ply strength. Methods of use vary from type to type, always follow the manufacturer's instructions.

Some people find epoxy unpleasant and messy to use and some become sensitized to it, and as noted above it must be protected from the Sun's UV by a suitable varnish or paint and that protection must be maintained year after year.

Other waterproof adhesives include Titebond III, which I find is OK most places in a boat but not under the waterline and maybe not if the boat will be left floating for long periods: for a boat that is removed from the water and dried it is fine, and much easier to use than epoxy, but it will not fill gaps so the joints must fit well.

If the boat is "dry-moored" and the extra strength of glass cloth and epoxy coating is not needed then paint or varnish is adequate. Good quality exterior grade latex house paint is probably more durable than oil paint, but it doesn't provide a perfectly watertight seal, some moisture passes through in both directions.

Personally having tried both I would spend a little more on the plywood and use marine ply rather than exterior grade ply. You can use thinner ply so it will be lighter, it will be easier to finish properly and you will have no nasty surprises.