Thread: Start Building Another Dutch GIS

Another update;

Today I did some epoxycoating. The mast has 2 extra coats and some glass wrapped around the square bottum part and rounded top. The yard has also 2 extra coats and glass around both ends.
I also did a first coat on frame 4 and on the centerboard foil.

NB I normally prepare wood before epoxy coating with pretty course sandpaper ( 60-80 or beltsander ) . I apply a generous first coat of epoxy and after that has cured I start sanding toward a finer finish. In my experience wetting bare wood with epoxy always gives a pretty rough surface and feelable woodgrain, so it's useless to make a very fine finish on bare wood. I also fill small holes after this first coat. I like to have thin epoxy into deeper holes before filling.

few pictures attached

Howdy,

That is a bit coarse. For the best adhesion US Forests recommends using 100 grit paper and making sure it is not too worn out.

Use the sliding roller method to make the surface pretty smooth. Daddles is the local expert. It doesn't produce a perfect surface, but much better than just straight rolled.

Best wishes
MIK

Hi MIK,

I do agree it's a bit course, I normally use lots of 80 as a kind of standard on bare wood.

In this picture you see what I mean by that feelable swelling of woodgrain, due to wetting with epoxy. I made this foil using 40grid beltsander ( quick job, but don't make any mistake ! ) and applied a generous first coat of epoxy.
Next step is sanding that down with 80 before next coats. In my experience that gives a nice smooth surface, eliminating this step of fine sanding on bare wood.
For perfect brightwork I allways use a finer grid ( 80-120 ) by hand following the woodgrain, to eliminate scratches made by the course beltsander. You fill those with epoxy, but sometimes you can still see them through the varnish.
I will paint these foils anyway, so I do not care how this wood looks.

I normally apply epoxy with a disposable square brush, but on bigger surfaces I will certainly try rollers and your sliding technique. Do you use standard foam rollers?

Regards
Ralph

Hi Guys,
I recently finished my little PDRacer, which was my first try at boat building, and epoxy work. When you talk about the sliding roller technique, i feel like i must have been doing something wrong, as i had great difficulty getting it to work for me. I don't know if i was going to thick , or using the wrong kind of roller, but when ever i went to slide it I just ended up putting big streaks into everything. In the end i did all my coating with a cheap 4 inch chip brush. It worked, but i feel like if everyone else is having success with the roller, i must be missing something.
Thanks, Al
P.S.
Have a wonderful trip here in the states MIK!

Originally Posted by alzuger

Hi Guys,
I recently finished my little PDRacer, which was my first try at boat building, and epoxy work. When you talk about the sliding roller technique, i feel like i must have been doing something wrong, as i had great difficulty getting it to work for me. I don't know if i was going to thick , or using the wrong kind of roller, but when ever i went to slide it I just ended up putting big streaks into everything. In the end i did all my coating with a cheap 4 inch chip brush. It worked, but i feel like if everyone else is having success with the roller, i must be missing something.
Thanks, Al
P.S.
Have a wonderful trip here in the states MIK!

I wonder if you're putting the epoxy on too thick. I use a squeegee (piece of stiff plastic or ply or playing card) to spread the stuff - this makes for a really, really thin layer (three coats is a minimum for me). The roller then flattens and evens it out with the sliding roller to take off the 'roller dimples'. It sounds like a lot of steps but once you get going, it isn't.

Richard

Hi Richard,

I am normally using a disposable paint brush to apply epoxy. I think that gives me better control on thickness and less dripping. Kind of varnishing with thick varnish technique.
I like rolling technique a lot with paint and varnish ( better thickness and smooth coat ) but with thicker epoxy I have the impression that you get a thicker coat and more sagging and dripping.

What is your idea or comment on this?

Hello,

For larger surfaces, I prefer to apply the epoxy using a roller and then to tip it off (smooth it out) using a disposable brush. I just don't seem to be able to do a proper job using the sliding roller technique; just like Al I tend to end up with big streaks everywhere.

This way I seem to be able to apply nice thin coats and it avoids doing a lot of sanding as everything is usually pretty smooth already.

When doing a smaller epoxy job, I usually just use a disposable brush.

Regards,

Joost

As soon as you use a brush, you are applying far too much epoxy. Seriously. Even a brush cut back to about 1cm long.

When doing the bulkheads on the Little Black Dog, I had a flat area of ply plus the framing. The flat area could be spread with the squeegee (a piece of 2mm thick plastic), the frames (19mm sq) had to be done with a cut off brush. Despite my best efforts, a lot more epoxy went onto the frames than onto the much larger, flat areas - a brush does not give you much control over the amount going on.

The beauty of the squeegee/scraper, is that you scrape the epoxy and can spread the stuff a loooooooooonnnnnnnnngggggggg way - all I'm aiming for is to wet the surface relying on repeat coats to build up the thickness. The roller is just used to even things out with the sliding roller to flatten the dimples. For example - the sides on the Little Black Dog are 15' long and somewhere between 1 and 2 feet wide - that's a large area to coat, yet the final coat took only one pump of West for each side.

Richard

Ok, i think I'm starting to understand. I probably am just applying too much epoxy. Didn't realize it was a wet the surface and then remove excess kind of thing, more pictured three layers of epoxy on top of the wood sealing it with a glossy coat. I'll give the lighter touch a try next time. Probably builds a lighter boat. I'm planning to start a GIS this winter, and i want to take a lot more care with that one than i did with my little ugly duckling.
Thanks,
Al

Hi Al,

The three thin wet-on-wet coats will give you a glossy finish. The plywood will absorb a lot of the first coat and it will look a bit flat, but the second and third coats end up with a glossy look.

Bob

Originally Posted by BobWes

Hi Al,

The three thin wet-on-wet coats will give you a glossy finish. The plywood will absorb a lot of the first coat and it will look a bit flat, but the second and third coats end up with a glossy look.

Bob

And if you're as miserly as me, it might take a 4th coat

Sand the plywood nice and smooth first too, otherwise, when you come to sand it back, you wind up with glossy streaks in that nice matt surface. Guess how I know this

Richard

Sounds good. I'm sure I'll find a reason to give it a try soon. Big surprise, i rushed the build of my ducky, not something to do next time. But next time, when i'm knee deep in sawdust and feeling antsy, i can just put the plane down and go sail in the less pretty boat i made this year. I'm gonna make some oars soon, so i'll give this a try on them.
-Al

Oars being the wrong shape ie, not flat, try using something flexible as a scraper. I bought a pack of giant sized playing cards years ago and seem to remember they worked a treat (and you don't mind tossing them out) but haven't used them since I got my stiff plastic scraper.

Richard

A lot of people including Mick espouse the idea of epoxy coating the bare wood with something like 3 coats before applying the topcoats of a proper UV resistant finish. What is the reason for this? Why not just use a 2-pot marine PU to start with?