Thread: Epoxy, varnish, and Sanding: the Ordering Thereof

You can assume that whatever you don't sand will show in the finished product. Sand until you're sick of it, then put up with the result. If you're like Mik, you produce a show boat. If you're like me, you produce a work boat.

Richard

And yes, that was meant to indicate you need to sand before the poxy.

Richard
hate sanding, hate sanding, hate sanding

Richard is right - it doesn't matter whether it is boating carpentry, turning, joinery or ordinary woodwork - the more you smooth at every stage the better the finish. That doesn't always mean sanding - if you can get a good finish with a blade (eg by using a smoothing plane or a scraper) that can be better than sanding. But the general proposition remains - get it to the best surface you can make and then start really sanding.

In my case this is the result of bitter experience. I have too many pieces where i thought "that'll do" and started putting the finish on. All the little things that I hoed that the finish would hide, were magnified by the finish!

One suggestion - get hold of as many finishing and sanding machines as you can afford! Good planes reward you by being fun to use and giving a good finish (better than I used to do with sandpaper). Then kill some electrons with a ROS (I just use the Triton attachment on my angle grinder) and finally do it by hand to finish off.

And if there is wood and/or glass and/or epoxy being sanded and turned into dust, use some kind of dust mask or respirator!

Howdy Michael,

Good to see you here!

Richard is being a bit generous with the level of my workmanship!!

With a job I'm being paid for I can do A-class work - and YEP it's all sanding.

With my own work I often tend to skimp with detail - usually my purpose is to get some bundle of ideas on the water - I'm not that concerned about the absolute level of the work - so long as it is durable.

But to the point here -

Sanding the timber - generally I do sanding of the details - making sure the various corners are rounded or sharp or whatever they are supposed to be. Basically all rounded to a radius similar to the thickness of the ply except for the back end of the boat and the last bits of the chine where you want a sharp edge for good water breakaway when planing.

Also any joins between the ply sheets to make up one panel - in the russki there are only the two short ones on the decks (from memory) - there might need to be a bit of fairing but be careful not to go through the veneers.

As far as general sanding of the ply surfaces - don't do too much - just a bit of sanding for any dodgy bits - otherwise you start cutting into the veneer and reducing the stiffness of the ply - if the ply looks OK it probably is. I would generally use 180 or 220 grit sanding in line with the grain

If sanding timber use sharp paper - once it starts cutting slower get rid of it. The sharp paper (or edged cutting tool) cuts the wood surface cleanly leaving the wood cell structure open for the epoxy to go down - increasing the surface area it bonds to. Blunt tools or worn paper crushing timber across the cell opening.

If painting a lot of fairing can be done AFTER the hull is epoxied, but if varnishing you don't have the option. The interesting thing is that varnish is much better at hiding poor surface (see the appendix to the plan) than paint is.

Best Regards

Michael Storer.

Thanks for the replies, and the tips. I shall sally forth and apply my crisp new sandpaper with gay abandon. Or with an effort to be joyful, at least.

Mik, where are those paddle plans then?

Originally Posted by MichaelB

Thanks for the replies, and the tips. I shall sally forth and apply my crisp new sandpaper with gay abandon. Or with an effort to be joyful, at least.

Nah, just forget all those dreams of building show boats. Work boats is good and can still have a stunning finish. A boat works best when it's worked ... and battle scars are part of that character, even if they were inflicted during construction

Richard
make sure your boat has at least one honourably earned blood stain - it'll sink if it doesn't ... not that I'm supersticious or anything

(how the bloody hell do you spell superwhateverthatwordisthatmeansyoubelieveinstuffyashouldn't?)

An observation on sanding and dust. When I was building my canoe I did a lot of sanding. At the points where I was sanding glass or varnish I used "wet or dry" sandpaper. The major advantage from my point of view is that it did not produce airbourne dust that gets all over the place. Clean up was as easy as pouring out the water at the end of the sanding process and cleaning up any dust laden drips. Needless to say I was not using an electric sander. I was pleased with the finish that I got and don't really see a downside if one is hand sanding.

When sanding the final layers of varnish I user progressivly finer sandpaper. I think that I ended up useing 1200 grit which I followed up with a light cutting polish.