Denatured Alcohol

This time, I didn't use water.

I took the advice of some other, and frankly more talented, boatbuilders. After sanding the surface (again) and vacuuming the epoxy dust away (again), I wiped the surface off thoroughly (again), but this time with denatured alcohol.

WHY denatured alcohol? To tell you the truth, I'm not sure. My best guess is that it evaporates more quickly than water. All I know is, I used it based on qualified advice, and it worked.

Floor beam sanded (again) and wiped with denatured alcohol

I also sanded one of the gussets (again). Looks like I went through the epoxy.

And, I sanded this gusset. Again.

So, after sanding and cleaning, I applied a thin coat of epoxy (again) using a thin foam roller and cheap foam brush as before.

This is what the offending surface looked like before.

Same area, after sanding, cleaning, and a fourth coat.

You can even see my coffee mug reflected in the surface.

Encapsulating: Make sure it's dry first.

So, what's the great mystery about applying the third coat? Procedurally... nothing. It's the same as the first two coats:

1. Sand it.
2. Clean it.
3. Epoxy it.

Let's revisit that "Clean it" step. The way I do it is to vacuum the surface thoroughly, and then wipe it off thoroughly with a moist rag. This is all to remove the epoxy dust left from sanding.

However, what happens if you sand the previous epoxy coat(s) a little too thin? Apparently, moisture can indeed get through it and into the wood. If that happens, I have learned to wait as long as necessary for the surface to dry thoroughly.

Otherwise, you get this:

So, guess who's getting sanded for a fourth coat of epoxy?

Thank you for taking time to read my blog. I hope you had a happy Thanksgiving, and a sane Black Friday.

Repeat for second coat

With the first coat of encapsulating epoxy now cured on the frame, the next step is...

Well, the next step is to repeat the whole process. (Surprise!)

First, I lightly sanded the surface with 220 grit sandpaper. Then, I vacuumed the surface a few times. After that, I wiped it off with a rag moistened in hot water to clean away the epoxy dust. Then, of course, I let it dry completely.

First coat, before sanding.

First coat, after sanding.

Detail shot of the sanded first coat.

Then, I applied the second layer of epoxy with a thin foam roller and a foam brush.

Second coat applied to the aft face of Zip frame #2.

Detail shot of second coat.

Stay tuned, to see what mysteries await us in applying the third coat!

Surface prep for encapsulating

It occurred to me after my last post that I should probably include a little more detail about this encapsulating process. 

After all, one of the main reasons I'm writing this blog in the first place is to hopefully be of assistance to the first-time, amateur boatbuilder. I want to help those who, like me the first time around, may have little to no experience at woodworking or even with boats.

To that end, I'm happy to share the mistakes I've made and the lessons I've learned along the way. I'm certainly not a professional boatbuilder, and therefore I'm not trying to "teach" anybody anything. I'm just sharing my experience, in hopes that it will help someone else build their own boat.

In this post, we're putting the first coat of encapsulating epoxy on the aft face of Frame #2. Now, on to the pictures...

Wrong color of wood filler

With my Zip build, I am placing a much higher emphasis on the overall fit and finish than I did with the Utility. One of the lessons I rapidly learned is that the wrong color of wood filler sticks out like a sore thumb. The photo above shows DAP Plastic Wood in the "natural" color, used on Meranti plywood. As you can see, it clearly does not match. Not even close. The darker areas are where I used epoxy thickened with mahogany wood dust to fill in the screw indentations. For my purposes, this mix-match doesn't matter in this case, as the plywood gussets will be painted.

Testing the Elmer's Pro Bond in "walnut"

Here, I'm trying out Elmer's Pro Bond wood filler in the "walnut" color to see how well it matches the Meranti. Not bad, in my opinion. It's certainly not up to perfectionist standards, but not bad.

Another lesson I learned from my last build is to slightly round over the edges of the wood surfaces. This allows the epoxy to coat the edge more evenly, without building up a "bead" along the edge.

Wiping the surface with hot water

I sanded all of the surfaces to be coated with 220 grit sandpaper. Any uneven or rough surface will show all the worse in the finish coat. In addition to meticulous sanding, I also vacuumed the surface multiple times, and then wiped it off with hot water.

Wax paper is indispensable to prevent you from gluing boat parts to your work surface. Yes, I learned this one the hard way.

Here, in preparation for mixing and applying the epoxy, I've gathered all the items I'll need. The little italian ice cups from Luigi's or Lindy's make great mixing containers for small batches of epoxy. A kitchen scale is invaluable for quickly and accurately mixing epoxy. I learned to keep it in a freezer bag to protect it from epoxy drips. Thin foam rollers are ideal for spreading epoxy, and they do a MUCH better job than brushes — especially cheap chip brushes, which leave bristles stuck everywhere in the epoxy. Foam brushes are perfect for getting epoxy into corners. Latex gloves are essential for protecting your skin from epoxy, and I learned to keep a rag handy for wiping up spills, etc. It's not fun to go looking for one in the midst of working.

First coat of epoxy

And here, we have the first coat out of three for encapsulating the aft face of Frame #2. As you can see, the mismatched color of wood filler I used on the frame gussets sticks out like a sore thumb.

Elmer's Pro Bond wood filler in "walnut," used on Meranti marine-grade plywood.

The Elmer's Pro Bond in "walnut" is certainly a better match. It's not perfect, but not too bad.

Encapsulating.

There's really not a whole lot I can say about this part of the process. 

The term "encapsulation," as it relates to boat building, refers to coating the wood with multiple layers of epoxy. The purpose is to seal the wood against moisture in an effort to prevent rot. 

The book, Boatbuilding with Plywood by Glen L. Witt, recommends that you apply at least two coats of epoxy — preferably three.

Lately, I have been encapsulating Frame #2... at a rather leisurely pace. I have been applying the epoxy with a thin foam roller, as well as a foam brush to get into the corners.

Second coat of epoxy on the forward face of Frame #2.

Second coat, sanded in preparation for third coat.

Third coat, on the forward face of Frame #2.