What I learned from ignorance

It’s funny how the timing of things works out. I have been pondering what I wanted to write about next, and wouldn’t you know, a good topic just popped up because of my own ignorance. So you see, sometimes ignorance does pay off.

Last week I won a nice piece of a walnut log in a turning club raffle, so I put it up on the lathe yesterday and stared shaping it. As an added bonus, it had spalting in the sap wood so the bowl has a nice colored figure. The log segment was somewhat flat, so I made it into a nice shallow bowl about 9” wide and 3 ¼” tall. Using the techniques I learned from Lyle Jamieson, I made the bowl walls nice and thin, about 3/16” thick. The piece has a lovely shape and is very light.

Well, there is something you should know about turning green wood bowls with very thin walls. The bowl will not hold its shape and will start to oval in a short time, so you have to do all the sanding on the outside before you start the inside, and you do all the inside sanding as you shape the walls moving down toward the bottom. Using this technique, the shape is still supported by the material left to be cut.

So I completed the turning and sanding work, outside and inside, and took the piece inside the house still attached to the glue block, so I could hurry off to a meeting. Here’s where the ignorance kicks in. I knew the bowl would change shape, but I figured I could still mount it up, and use a dark brown wax stick on the inside to give it a nicely polished wax finish on the inside. Needless to say, things did not work out as planned.

When using a wax bar for a piece mounted on a lathe, you hold the wax bar against the spinning piece of wood, then melt it in with a paper towel by applying light pressure. The high RPM rate and the friction of the paper towel creates heat which will melt the wax creating a nice even finish. Well that’s the rub (yes, pun intended), if the piece is not round, the wax won’t get applied evenly. So what do you get? A mess and more time sanding. (Which is just what every turner loves to do! Smell that? Yes sir, sarcasm baby.)

I knew that the wax would just clog up the sandpaper if applied straight away, so I softened the wax up with mineral oil and more friction heat with steel wool. A couple of pieces of 220 grit sandpaper later, the wax was pretty much off, then I went back with more coats of mineral oil, then 320 grit, more oil and 600 grit, then one last coat of oil. After all that work, it looked quite nice.

The walnut bowl of ignorance

If I ever need to do that again, to an ovaled bowl, I will dissolve the beeswax to make a paste wax, and apply it that way. The overall lesson being; if you turn a green wood thin-walled bowl, you need to be prepared to stay at the lathe to do any finishing work that needs to be done. Another lesson learned in ‘As the Lathe Turns’.


About yaakov

Husband, Abba, Furniture Maker, Turner, Bookseller, and all around working stiff.
This entry was posted in In Yaakov's Workshop and tagged , , , , . Bookmark the permalink.

4 Responses to What I learned from ignorance

  1. bob says:

    That is a nice looking bowl!

  2. It’s amazing how fast they oval, isn’t it? I’ve had some pieces change so fast that they blew up on me as I turned because they reshaped during the cut! Hey, at least you managed to save the bowl.

    Things like that tempt me to invest in some of those “buffing balls”.

  3. Andy Coates says:

    Nice save, Yaakov. You’ve ended up with a pretty bowl after all that effort.

    Another trick you can use when turning thin walled greenwood bowls is to spray them with water as you work. The water will stop the loss of cellular and inter-cellar water whilst you turn, and if you use good quality cloth-backed abrasive you can even wet sand as well…it’s cooler so reduces heat checking, and too-fast drying due to the heat from abrasion, and the final abrasion is better having been cooled. The slurry can also fill the pores as well which gives an almost gesso like base for your finishing. Drying the bowl prior to finishing can be done with gentle heat from a hotair gun, hair dryer, or friction from the last (un-sprayed) grade of abrasive. Give it a try and see what you think.


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