Monday, July 5, 2010

Sam Johnson Demonstrates

Sam getting things fired up.

He's always moving, constantly explaining.

His little furnace is homemade, a five gallon metal bucket modified for the purpose and lined with refactory material, fueled by a propane jet.

Sam explaining the two part flask, a container for the sand mold. In the corner looking on is Tom Jackson, senior editor @ WB publications.
Today I read Tom's article in the 2009 Small Boats by WB about the Frederickssund Jolle collected by Christian Nielsen. This boat is featured in the out of print Wooden Boat Designs (english version) which had an introduction by Jon Wilson, founder of WoodenBoat. Tom's article is right on point, she's a wonderful boat, among many in the collection of drawings at the Danish Maritime Museum. There is a cantankerous CD offered by the Museum which has all the boats surveyed by Nielsen. My favorite is an18' ish sailing pram, but if you go to the trouble to find the book or buy the CD, I'm sure you'll find your own favorite among these incredible Danish boats.

Here he's fitting the cope to the drag, upper and lower pieces of the flask.

The mold is executed using oiled sand tamped in aroung the dersired object. I was so taken with the pentimento effect of this stage heightened by the white powder that is a parting compound, that I forgot to take a photo, this was generously supplied by fellow blogger John Almberg who writes The Unlikely Boatbuilder. John must have been standing next to me during a portion of the demo, but we didn't recognize each other as fellow bloggers.

More of the process for preparing the mold here,


And here.

Mold done and in place, Sam checks the color of the molten bronze, not using a thermometer, but his knowledge and experience, his eye.

He's using an iron rod to skim debris from the surface of the melted bronze which is in a small crucible.

The pour!

The molten bronze is filling the cavity in the mold.

After letting it cool a bit, Sam separates cope and drag...

...and extracts the still hot piece from the mold.

Cope and drag with the casting removed. I find these very compelling images, a result of the process but to me they read as wonderful drawings.

Viola, the newly minted silicon bronze oarlock!

In a matter of minutes Sam is on to the next casting, here sprueing a mold for the sockets the oarlocks will fit into.

all photos Thomas Armstrong except where noted

First thing Sunday last at the WoodenBoat show was a demonstration of backyard bronze casting techniques by Sam Johnson. Sam has worn many hats in his lifetime, he's a boatbuilder, a foundryman, a teacher. He currently maintains a shop in Seattle, but is also the director of the Columbia River Maritime Museum in Astoria, OR. He also teaches workshops on bronze casting for boatbuilders at the Center for Wooden Boats in Seattle and at the WoodenBoat School. Sam's teaching style is energetic and informative. He neatly demystified the previously esoteric process of sand casting mold making and pouring in his hour long demo. Having long stood on the fringes, this demo reignited my interest in this craft and empowered me to believe it would be within my grasp. That's what good teaching is all about.
While it's a little hard to imagine the affable and voluble Sam Johnson in business attire attending a board meeting, I'd be willing to bet he's no less formidable in the board room than he is engaging and didactic in the the teaching environment. It was a pleasure to meet you Sam, and thanks for some insight and inspiration.
I'd like to say that a far more coherent, instructive and lucid account of this demo can be found at John Alberg's The Unlikely Boatbuilder.


doryman said...

Sam is a very energetic fellow. He is the catalyst behind the current small boat documentation project here on the Oregon coast. We had a lively meeting at the museum in Astoria last fall.
There is no pretense in the man, what you see is what you get, board room or foundry. He told me he often wishes he was back casting bronze in his own shop.

I was perplexed at first when I saw Sam's picture here... I thought "when was Thomas on the west coast, and why didn't he get in touch?"

The reports from this years WoodenBoat Show are very compelling. Sure wish I'd been there!

will said...

very enjoyable. love this post!!