Thread: Finally building Eureka

Everyone has a favorite epoxy, for whatever reason. I use several different brands. All have their issues and all will blush, regardless of modifiers added to the goo. Fast and medium Marinepoxy will blush, but the slow will not in most cases, unless you're building in a high humidity, high temperature environment. I sold some epoxy to a fellow last summer and he called and said it blushed like crazy. Later in the conversation he also admitted he was working in 90+% humidity, sometimes with a pouring rain just outside the garage door, in 90+ degree temperatures. Well folks, I don't care who's epoxy you use, but it's going to blush in that environment.

Blushing can't be avoided. Contrary to what advertising and labels on products say, some unreacted amines will collect on the surface, more if conditions promote it, less if modifiers are added to the epoxy.

Anyone assuming they have blush free epoxy and not washing and sanding prior to subsequent coatings are just pushing their luck. Unless you have a climate controlled shop, where you can lower humidity below 50% and keep temperatures in the 70's you're kidding yourself about blush.

Frankly, the wise builder always assumes there will be a blush, washes and sands the surface in prep for the next coat of epoxy, primer, paint or varnish. I installed A/C in my shop a few years ago and it has made a huge difference, but I still assume a blush will be present, even though the conditions in the shop are near perfect.

MAS isn't much cheaper then the other major brands. I'm seeing it sold by the gallon at just under the major brand pricing, while Marinepoxy is easily 20+% lower in cost.

Howdy,

I often think that advocating epoxy really depends on what you have used the most - and are most familiar with.

What we all want is a predictable result. Unfortunately, or perhaps happily, the only way to get a predictable result is to spend time with a particular brand.

There are some things to avoid as far as choosing between brands, and the most useful source of information is finding a lot of people that are using the same brand. If it is not a well known brand that does increase the risk.

The other things to keep an eye out for is that the brand's ratio should not be 1:1. This implies a large reduction of quality. There is one exception I know of in the market ... System 3 does have a 1:1 epoxy and they are hugely respected as manufacturers and innovators, so I would admit that one as the exception. But 1:1 is not a big advantage even in that case.

Another thing to avoid is any hint of a solvent smell from the hardener or resin bottles. Solvents are strongly frowned on in epoxy boatbuilding. They imply weakness and also that the epoxy will not be as waterproof as the construction method depends upon. There should only be a smell of ammonia if you sniff the epoxy.

The final thing I would avoid are the prethickened or pregelled epoxies. These are often 1:1 as well. They are quite useful for woodworking, but I have seen enough cases where they have caused problems that I won't recommend them - most of the reputable manufacturers do have something like this in their range, but normally sell the unthickened prroducts for boatbuilding. One example was a 30ft boat where the glued components could be pulled off by hand several months after curing.

So is best to buy the stock resin and hardener and add the powders yourself to thicken it up.

Best wishes
Michael