Saturday, November 5, 2011

Boat Soup Greenland Paddle Finish

I've received quite a few inquiries asking about how I make and apply the finish for my greenland kayak paddles, so I'll detail it here.  What's amazing about finishing wood is the degree to which its fodder for so much pseudo-scientific babble and art; so much so that sometimes the would-be finisher feels lost before he starts.

Well, its SIMPLE.  It is.  At least this method is.  So don't psyche yourself out.  Here's what I do.

I use "boat soup", an informal term used in the marine trades for a mixture of oil, turpentine and pine tar.  The important thing to remember is this: there is no exact recipe.  So you exact engineer types can just get over it.

Traditionally, boat soup was equal parts of linseed oil, pine tar, and turpentine.  My version is light on the pine tar, and I substitute tung oil for the linseed oil.  Additionally, I use cobalt drier to speed the drying process for me, a builder who needs to get paddles and boats out in a timely fashion.

Some words on ingredients: I try to stay away from petroleum-based stuff.  I use raw tung oil, turpentine and real pine tar.  Beware of petroleum-based pine tar; its inexpensive and smells bad.  Bickmore's, for example, is petroleum-based.  The real stuff comes from pine trees.  I often use cobalt drier, available at art supply stores, to speed drying.  Its nasty stuff, toxic, and even though it doesn't smell bad, its unwise to breathe it or come into contact with it.  I don't use Japan drier anymore, it doesn't work on tung oil!

Use them!

The first step in any quality finish is quality preparation.  If you do a good job sanding, a good finish will result.  That said, here's what I do.

1. Pour some raw tung oil into a clean container
2. Pour an equal amount of turpentine
3. Add some pine tar.  I use a spoon to meter it.  I add enough to get the color I want.
4. Stir.  If the color is what I want, I leave it there.  Too light?  Add more pine tar.  Too dark?  Add more tung oil and turpentine.  What I'm trying to do is get the benefit of the protection pine tar provides, while avoiding the dirty look too much pine tar will cause.  I also must consider drying time.  Too much pine tar will lengthen the drying time to an impractical degree.

Here is what I'm going for:

5. If you choose to use cobalt drier, add it now.
6. Apply the mix with a brush.  Just slather it on, there's no need to do a nice job, just make sure the coverage is even.
7. Wait 20 minutes
8. Wipe off the the excess with a lint free rag, then let it dry overnight.
9. Second coat, same thing.
10. Third coat, apply finish, wet sand with 600 grit wet-dry sandpaper until smooth, wipe off excess with a rag.  Let dry overnight
11.  Fourth coat, same thing, but wet "sand" with #0000 steel wool.  Let dry.

At this point, it will be looking pretty good, and depending on several factors, you might want to keep adding coats, always wet sanding with either 600 grit wet-dry paper, or with #0000 steel wool.

I live in the Pacific Northwest.  During 8 months of the year the weather is so damp and cold that this finish will not dry.  I use an portable oil-filled electric heater and a tarp to speed things along.

You can of course keep going with buffing and polishing compounds, but why?  Remember, its just a kayak paddle!