Wednesday, May 20, 2009

In Praise of Cherry

There are three chairs in my shop waiting to go out and a flurry of oiling and rubbing happening to get them ready. Each time that the oil hits the cherry, it glows a bit deeper and richer, which is good fun (although rubbing the oil off is another matter!). While building these chairs, I couldn't resist placing the lovely inclusions and markings in prominent places. I've talked before about the difference between designing for a painted piece and one left natural. In my book, they both have their strong suits, but in this case, I have had a lot of fun leaning on the appearance of the wood to accent the design. Below is the front right leg of the rocker that I am crating up tomorrow.

It's like a little painting! Of course, the other desirable aspect of working with cherry is the color and patina that only time can truly bring. The photo above and the two below are a timeline of the color shift. I made the chair above a few months ago, the one below has been finished for about 5 weeks and the third is about 1 week old. The longer that the cherry is left unoiled and exposed to the air, the quicker it seems to take the color, although, in time, it all seems to even out.

Quite a difference from the first image to the third. The photos also highlight some more of the lovely markings that I've been coming across while finishing the chairs.

Below is one that I came across under one of the arms. Just like in painting, I believe that you can't finish what you aren't looking at, so I spend a lot of time contorting myself to see the areas that oil just loves to pool in.

One benefit of using turnings in the natural chairs is that you get to see the tangential and radial planes in their full glory. Here's the radial plane on a chair leg.

Here is the arm of the rocker. I'm showing it to demonstrate the level of sheen that I like to achieve on the finished piece. Normally, I send chairs out the door slightly shinier than I actually like, knowing that the finish tends to dull in the first year.
This brings up a question that I often field about the varnish oil mix. The simplest answer is to mix 1/3 oil, 1/3 spar varnish and 1/3 mineral spirits. But that doesn't really cover the whole story.

The oil is affected by the three ingredients to different ends. Too much varnish and the oil will build a finish in fewer coats but be difficult to handle and will tack up too quickly to remove easily. Too much tung or linseed (boiled will cure faster but has driers) and the oil will be easier to remove but the finish will take more coats to build. The mineral spirits thin the oil to help it flow and soak in, I like a thin first coat to soak in more deeply, but too much spirits in the final mix will require more coats to build the finish as well. So just like any tool in your shop, which needs proper selection and care to achieve the task at hand, subtle adjustments to the oil can help turn finishing into something besides mindless rubbing...and rubbing.


Anonymous said...

Is spar varnish the same as polyurathane , matt, satin or gloss? , here in Australia I use just boiled linseed oil and turps on the native hardwoods , I would like to try your mix.

Peter Galbert said...

Polyurathane is not exactly the same as spar varnish, but for most practical purposes, it can be treated the same. I use gloss because satin and matt have small particles added to break up the light as it reflects off the surface. Boiled linseed on its own is a fine finish, but it won't build or dry as fast and the varnish gives more protections against scuffing and water.

Kari Hultman said...

Peter, what about finishing with blo and then using varnish or poly on top as a protector? Do you prefer tung oil over blo?

I'm with you on cherry--it's a joy. It has a warmth to it that I've never seen in any other species. Fortunately for me, there is a ton of it around here.

Peter Galbert said...

I think that the blo with varnish over it is fine. It really comes down to time, in my shop when I'm trying to get work out the door, the varnish helps a lot. I prefer the natural tung (from the Real Milk paint company) because it builds an amazing finish on the lathe and I don't have to worry about toxic driers. But later when I mix it with spar, I am careful to avoid contact!