June 7, 2012

Protecting the Exterior Walls

One of the main design elements we wanted to achieve with our camper was to make it look like a home built 'woody'.  To achieve this we used marine grade Okoume plywood for the side walls with the intention that we would stain and seal them.  We figured this would be one of the last steps in our build, but after a couple of heavy rain storms, we were starting to notice a little bit of water damage on the plywood.  Though marine grade plywood is engineered to better withstand the elements, it still needs to be sealed and all we had protecting the trailer since January was an old tarp.  Our schedule quickly got updated!

Before we stained anything though, I needed to sand the living daylights out of the Okoume.  After sitting outside for 5 months, the wood really opened up and dried out.  Running your hand along the wood you could feel how rough everything had become.  I went to town for the better part of the morning sanding first with 100 grit sand paper to smooth things out and then with a finer 220 grit which was recommended in the stain instructions.  After vacuuming of the dust and wiping things down, it felt nice and smooth.

When we first cut the Okoume into the tear shape, we saved a few scraps to test stains on.  The one we ended up liking the best was a Minwax stain in Provincial #211.  It seemed to have a nice rich color without being to dark.  Now that the trailer was built, I was really nervous about staining the whole thing, so we tested the stain out again to see how many coats we needed to get the right depth of color.  One side I did a single coat and on the other there are two.  We decided that though the two coats were really pretty, one coat showed off the grain more which is what we were after. 

So it was finally time to take the plunge - there was no going back!  I painted on the stain with a foam brush and Darrell came after me with a clean rag to wipe off the excess.  It looked amazing!  The grain was perfectly accentuated and the color was just right.  It was perfect!

look at that wood grain!!

The next step was to seal everything in.  We actually talked with one of our neighbors who is a contractor about what to use.  We initially thought to use polyurethane like the galley counter, but I was afraid how it would react with the Okoume and hold up in an exterior application.  He recommended using a Spar Urethane instead which was similar to poly, but made for outdoor applications.  Not only would it protect against rain, but also sunlight and temperature changes.

Following the instructions we painted on the first coat and were instantly impressed.  It went on somewhat easily and really made the wood shine.  After letting it cure for 4 hours, we sanded the surface lightly with 220 grid sandpaper, wiped it down and applied the second coat.  We let things dry overnight and in the morning noticed that a couple spots dried unevenly which was a bit disappointing.  We sanded everything down again - more aggressively this time - and carefully applied a third coat.  We let this fully dry and checked in the next day.  It looked great! There were a couple of funny spots, but only noticeable to us.  We were so glad we did that third coat.  The finish was really smooth and felt like it could stand up to a hurricane!

after one coat of spar urethane

We didn't really get any good 'after' photos, so here is an sneak peak photo showing a partially completed door!  The door is made from the Okoume we cut out of the side wall so you can really see the difference the stain and spar urethane makes.

1 comment:

  1. Looking good!

    One thing about spar varnish or spar urethane is that it will need maintenance. You'll probably need to sand and put on another coat every couple of years if it stays exposed outside full time. It's a good balance between durability and difficulty, though, and should prove to work well. :-)

    We've actually done a section of kitchen counter top in oak ply with three coats of spar urethane, and it's holding up well to heavy daily use as a counter. Only difference is the long term uv exposure. We have about eighteen months and haven't yet needed a re coat.