Epoxy

[JonnyBoats]

What are the different types of epoxy, and how much difference does it make which one is used for small projects on a boat? For example can one use the small tubes of epoxy from the dime store for bedding backing plates, or is that type of epoxy lots different than "marine" epoxy?

[Tim]

Any boatowner needs a supply of epoxy resin and appropriate fillers. Then, one can make any sort of mixture--adhesive, fairing, etc--anytime they want, and in the proper amount, thickness, composition, etc.

Little tubes of stuff from the hardware store have their place and purpose, but there's no reason to resist having an actual supply of epoxy resin on hand at all times. And that goes for going cruising, too.

[JonnyBoats]

Any boatowner needs a supply of epoxy resin and appropriate fillers.

What would you recommend for a "starter kit"?

[Rachel]

Let me just mention that no matter what you ultimately end up choosing, the free booket put out by WEST system is a must-have. It lays out very clearly what type of resin/fillers/texture to use for any number of typical applications. Although the examples use (of course) their own products, most of them have generic (or other brand) equivalents. System III also puts out a booklet (downloadable) that is useful, although I like the WEST one better.

I happen to like the type of resin that mixes in a 1:2 or 1:3 ratio, because I like to use clear beer cups for mixing cups (vs. pumps or a scale, which I believe you need for a 1:5 ratio). I've used MAS and System III, but there are others as well.

One thing I find very useful (especially so cruising, although one should also have larger quantities) are the "refill" packs of resin and hardener that WEST sells for their repair kits. The whole, pre-set kit contains things like one squeegee, a mixing stick, and a single syringe that I usually already have in bulk (in addition to the resin and hardener); but the refills contain only ten packages of resin/hardener (they're pre-measured and resemble conjoined versions of packs of ketchup that you'd get at a fast-food place, but slightly larger). When you have a small repair to make, you simply open both (conjoined) packs, squeeze them out, and mix, and you have a batch of "goo," just like that. They take up virtually no room, stowing easily in a small Zip-Loc bag.

There are lots of pre-mixed fillers and such these days (which I haven't really tried), but like Tim, I like the versatility of owning the raw ingredients and mixing what I want.

Rachel

[CharlieJ]

Couldn't agree more with both Rachel and Tim. And Rachels suggestion is a really good one. Simplest way I know to carry small amounts of resin.

[bcooke]

I got started with WEST System simply because it seems to be the benchmark that all the others compare themselves with. I figured once I knew the benchmark I would be able to adequately judge the rest. So far, I haven't had the need to try any of the other systems although I am quite sure many of them are equally good.

-Britton

[Tim]

Here's what I would call an adequate starter kit for most fiberglass boats. For the sake of argument, I'll list the West System products. If you use a different brand of resin, just buy the appropriate hardener. Note that you can use any brand of filler with any brand of epoxy.

The West System pumps can be sort of a pain, and I've never liked them. When they work, though, they are handy for small batches. Note that the proper mix ratio is built into the pumps, so to mix you use one pump of resin and one pump of hardener--not 5 resin and 1 hardener. Many beginners have made this error.

If doing a major project, or a continuing stream of projects, and choose to use West System, I'd highly recommend investing in the killer (but expensive) West System gear pump. It makes epoxy work a breeze--no measuring at all, and infinitely adjustable batch sizes. But for the typical boatowner, it's very hard or impossible to justify the $600-$700 price. It's too bad, because it's just such a handy addition.

You can measure West System in any sort of graduated container, though, just like the 2:1 ratio epoxies, so don't let the overblown stories of difficulty in measuring be the deciding factor in the resin you choose. If you can divide simple measurements by 5, I think you'll be fine regardless of which resin brand you choose. Just be intelligent about it; don't pour 3.5 oz of epoxy into a cup and they try and figure out what 1/5 of 3.5 is. Pour 5 oz in. Or 5 graduations, whatever they are, they don't have to be as large as ounces. Or use the pumps for smaller batches.

Don't ever guess at mix ratios; all epoxies require a pretty specific ratio, without a whole lot of room for error. You don't need to weigh it, though. You can get perfectly close enough with basic measuring devices.

Frankly, anyone working with epoxy resin ought to be able to handle mixing and measuring any brand. RTFD. It's really quite simple.

There are good reasons to choose any of the well-known brands of epoxy. Make your own decision based on the information and features you think are important. All the major brands work well and have good reputations, and there's no sense in arguing which is best. But each does have specific properties, with their own particular ramifications on the overall curing or performance characteristics of the brand. The reasons I continue to choose West System may not apply to you, or anyone else. I've used several brands with success, but have not found one I like better than West at any price.

Now, here's the starter kit.

• 1. Epoxy Resin (0.98 gallon container West System 105A)
  
  2. Epoxy Hardener (0.86 quart container West System 205/206A) 205 is a "fast" hardener for cool or temperate conditions; 206 is a "slow" hardener for warmer conditions. I normally use 205 year-round in Maine, but it definitely kicks more quickly in the warmth of summer.
  
  3. Cabosil/Colloidal Silica (West System 406). This is an adhesive filler used to thicken epoxy to make glues, and also to modify fairing mixes for proper consistency.
  
  4. Phenolic Microballoons (West System 407) This is a fairing filler that is effective and relatively easy to sand. It's suitable for use on deck and above and below the waterline. You need some of the cabosil to properly compose a mix of microballoons, though.
  
  5. The West System manual, Fiberglass Boat Repair and Maintenance, as mentioned by Rachel, is an invaluable resource no matter what brand you choose. So is the System Three The Epoxy Book. Get and read them both.

These basic components will do everything you need.

Perhaps the most versatile epoxy you'll find at the hardware store is the little tubes of kneadable epoxy "dough", which can be handy for emergency or short-term repairs. But I wouldn't call any of the hardware store epoxy-base glue products a true replacement or adequate substitute for actual epoxy resin.

[JetStream]

One interesting note about epoxies that is not very well published, is that all epoxy ratios are volumetric. If you mix by weight rather than volume, you need to account for the density difference between the resin and the hardener. Depending on the brand and the particular hardener, the density difference can be up to 10%. So, if you don't account for that and need to be within a 10% window to insure a good mix, you can be at the edge of your tolerance before you add any additional errors. The moral of the story is that it's easier to mix by volume.

[Quetzalsailor]

John, I second most of Tim's remarks except that I'm pretty partial to their microfibers (ground up tee shirts). Fiber is always good to add! I also save fiberglass or roving scrap in a little baggie; easy to reinforce small repairs, or chop up for better fiber, or even use unraveled roving to strap things together. I carry the A-size resin and slow hardner, microfibers, and microballoons, catfood cans, stirrers, latex gloves, and pump set aboard Q. Carry this stuff in its' own water- and resin-tight box. There is inevitable leakage and it's nasty stuff on you and everything else.

Read Gougeon's book. It's important to know the differences between the thickeners! One is a thermoplastic and the other is not. The thermoplastic can change shape over time in sun heat.

Doug

[JonnyBoats]

Here's what I would call an adequate starter kit for most fiberglass boats.

Thanks Tim.

How long does this stuff keep, particulary once it is opened? Also any tips on proper storage?

[Tim]

Shelf life is indefinite, unless the materials show visible signs of deterioration. Even partially crystallized product can often be salvaged, though unless you allow it to freeze this is unlikely.

The viscosity may change over a span of years, and the colors may change--particularly the hardener--but in general it lasts a very long time. When in doubt, and when beginning to use an old container that hasn't been touched in some time, it pays to mix a small test batch and allow it to cure to ensure that it works properly.

The fillers will keep forever if you keep them dry.

A gallon container may seem like a lot at first, but believe me: it's not really that much, and once you have it you'll use it for all sorts of things and wonder how you ever got along without it.

Microfibers are useful too, depending on the application. They thicken a mixture nicely and add some strength. For certain bonding applications, they're useful. But you can get by without them too. I have some on hand, but rarely use them, so I didn't include them in the "basics" list.

[CharlieJ]

One other type of epoxy I feel belongs on a boat. A good underwater epoxy. I keep a supply of Dolfinite ( often known as "black and Yellow") aboard.

Recently used some on a crack we sustained when the boat slammed bottom in 6 1/2 feet of water- ( it was a 3 1/2 foot wave).

It mixes with wet hands and can be mixed underwater if needed. Cures underwater. EVERY glass boat ( wooden ones too) should have a small quantity aboard.

I buy mine from my local NAPA store but we are a bay front town ( the shrimp boats all carry it) so other stores might not have it, but I'm sure they can get it. About a pint quantity cost me $16. Worth every penny.

[bcooke]

Dolfinite is an epoxy?!

My can of Dolfinite is a bedding compound -which I used extensively to keep my dory afloat - all to no avail.

Great stuff for wooden boats because it stays pliable and can accomodate the swelling movement.

[fusto]

I think he was referring to Z-spar's Splash Zone.
It comes in two tins, one is full of black goo and the other is full of yellow goo. You knead a handful of each into a clay-like blob. And apply liberally to... uh... whatever.

The fishermen here in the PNW like to use it on exposed running gear bolts. Rudder stocks, prop nut zincs etc. Keeps nets from fouling.
When we remove the running gear we have to chip it off with a hammer and a chisel.



The shipwrights use Dolfinite for bedding various wood bits. As far as I know its one part and never cures. Don't use it ever myself.

[CharlieJ]

LOL- Well MY containers are labeled "Dolfinite" *grin* Must be made by same folks.

Splash Zone more than likely is the same stuff though.

[Quetzalsailor]

As for all the hardware store tubes of epoxy: Why bother and why spend the money? You can concoct what you need from the West System and you can throw away the leftover from small batches for far less money.

I have used the various hardware store stuff and it's technically just fine. Strong enough, sets up reliably. A disadvantage is that it's often colored so that you can see the progress of your mixing, but it's seldom the right color. If you're using West hardners that have been open for a year or more, they'll have turned red, giving you the same information.

[fusto]

LOL- Well MY containers are labeled "Dolfinite" *grin* Must be made by same folks.

Splash Zone more than likely is the same stuff though.

Hmm maybe dolfinite is a brand name?

The Splash Zone we have at the yard is made by Z-Spar which is made by Woolsey which is made by Pettit...
At least I think thats how it goes.

Dont know who makes Dolfinite, but now that I think of it the cans do look kind-a like the Splash Zone cans.