Steaming walnut to increase yield kills the vibrant natural colors prized in un-steamed walnut.
Put The Life Back in Steamed Walnut
Walnut (Juglans nigra in the family Juglandaceae) is perhaps our most popular domestic exotic hardwood. The heartwood of walnut is rich brown with overtones of red, purple and cordovan. In my view there are no other domestic hardwoods, and very few exotic species, that offer the woodworker such a wide range of colors, both bold and subtle.
But, in order to maximize yield from walnut logs most commercial mills steam walnut lumber immediately after milling the logs into lumber. There are basically two methods of steaming; pressure steaming and steaming at atmospheric pressure. The details are not all that important for our purposes. In both methods un-stickered freshly milled lumber is subjected to "wet" steam (steam at 100% relative humidity) in a tightly sealed structure. Depending on the process, temperatures will range from190º to 230º and steam will be inserted into the chamber from a few hours to a a few days. What actually takes place within the walnut is subject to debate. Some point to "bleeding" of the extractives in the heartwood into the sapwood while others hold that the color change is the result of a chemical transformation involving sugars and starches in the wood. Whatever the cause, the result of the steam is the elimination of the cream color sapwood found in air-dried or un-steamed walnut thus increasing the volume of marketable lumber from each log (walnut grading rules treat sapwood as a "defect"). However, the increase in marketable yield produced by coloring the sapwood is not without cost. Steaming kills much of the desirable natural color of the walnut heartwood, eliminating the subtle color variations and turning everything, both heartwood and sapwood, to a dull monochromatic gray/brown. The striking color difference between un-steamed and steamed walnut is illustrated in the following photos. Please note that both samples were photographed at the same setting with the same lighting and the same camera. No finish of any kind has been applied to either sample. Both samples were run through the same helical head planer and neither sample was sanded ofter planing. What you see in these images is the direct result of steaming with only the labels added for clarity.
will not need spray equipment and no dangerous finishes are involved. Before we get into the specifics, however, let's first examine the process that we employ using a story-board. We highly recommend the story-board technique whenever considering a new finish schedule. Its proper use will avoid the frustration and disappointment that comes with jumping into an untried finish without first exploring the process.
In the following photo you see the story-board we created in the process of developing this finish schedule. The board was selected to illustrate the problem we are attempting to solve; creating the look of un-steamed walnut on a steamed walnut board that contains both heartwood and sapwood.
It is difficult to imagine that anyone looking at these photos would find the steamed walnut image on the right more desirable than the un-steamed image on the left. It is as thought we are examining two completely different species of wood. In the process of steaming we have taken one of the most vibrant, richly colored and unique species of lumber in the whole of creation and managed, for the sake of increased yield, to convert it into a bland, flat, nearly monochromatic material that must be artificially colored in order to even approach its former brilliance.
Somehow the whole idea of paying top dollar for a premium hardwood and then having to apply color to make it look the way it came naturally from the tree seems fundamentally wrong. Nonetheless, in the rest of this article we will do just that. We will develop a method of restoring the color of steamed walnut to its former unsteamed glory. Best of all, the schedule we propose will restore the color of the walnut without the application of a single grain of opaque pigment. By avoiding the application of pigment stains and relying instead on water-soluble dyes and the natural dye found in garnet shellac we will retain the beautiful grain pattern of the walnut without masking any of its grain structure beneath an opaque film. The process is simple; it can be accomplished without special tools in any hobbyist garage or basement shop. You will not need spray equipment and no dangerous finishes are involved. Before we get into the specifics, however, let's first examine the process that we employ using a story-board. We highly recommend the story-board technique whenever considering a new finish schedule. Its proper use will avoid the frustration and disappointment that comes with jumping into an untried finish without first exploring the process.
This story-board is 48" long and 4" wide. Since we knew that there would be just three steps in this finish schedule we divided the board into four sections, each 12" long. We created the divisions by making shallow cuts in the board at 12" intervals. The first section is left unfinished to give us a reference to the starting point. Each subsequent step is applied to all of the remaining sections of the board until the entire finish has been applied. To obtain the following photos of each step in the process we simply took photos of each step and then cropped each image to fit together at the saw cuts separating each step in the process.
Now, let's see how our schedule compares to a simple clear coat finish of varnish applied to un-steamed walnut sample. Again we selected Pratt & Lambert #38 and applied it to a walnut board that has not been steamed. The un-steamed walnut finished with P&L #38 is on the left and the last panel in our finish schedule (without the labels) is on the right. The transformation was easy to achieve and was done without the application of pigment stain. Note that the band of sapwood along the bottom edge of the steamed sample (photo on right) has been seamlessly blended into the heartwood above.