Step panels can give you a peek into the future - Woodshop News

Step panels can give you a peek into the future

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A very talented and accomplished woodworker of my acquaintance constructed a fairly large decorative object of solid walnut. A dealer commissioned the piece for display at a craft show and it involved metal as well as the wood. The desired finish was to be a warm brown, very transparent, very smooth but with little film build, emphasizing the figure and depth of the wood and contrasting with the bright-silver trim elements.

Two different craftsmen collaborated on this; one to do the wood construction, turning and finishing; the other to do the silversmithing.

Circumstances evolved during the production that required some changes and a delay in getting the wood to the point of finishing, so there was some pressure to speed up the finishing process in order to meet the deadline for the show setup.

The finisher had several dye stains available that he had used before and chose one he thought would be perfect for the project. 

He applied some of the stain to the underside of the construction and decided that the color did work well, so he applied stain to the rest of the piece. After the stain dried, he applied a coat of sanding sealer, let that dry and sanded it lightly with 240-grit (CAMI) sandpaper. He then used a broad metal putty knife to apply a grain filler to the flat part of the construction, let that dry overnight and, using burlap cloth on a sanding block, rubbed down the piece to remove any excess filler.

He then applied a thin coat of gloss, precatalyzed lacquer to the piece and set it aside to dry.

Here’s what he found when he returned to the piece: the stain was too dark, both in color strength and value (too much black). Since it was a dye, it was absorbed into the wood, not simply on the surface and interstices of the wood. It was absorbed more in the exposed end grain and less in the face and edge grain, resulting in an undesirable mismatch between contiguous pieces of wood.

The gloss sheen of the lacquer wetting out the wood and filler made it appear darker than it did when only stain was on the wood and also accentuated many tiny scratches in the wood surface made by small accretions of Bondo on one side of the putty knife, which had not been noticed by the finisher.

The brown-colored filler, somewhat darker than the dye stain, also contributed to the visibility of the scratches, especially those that crossed the grain of the wood.

What went wrong?

The finisher consulted me for advice on remediation of the issues: correction of the color, evening or blending the color across the diversity of wood surface and eliminating the scratches.

While the finisher had intended to use a dye-type toner to uniform the color somewhat, there was too much color in the wood for that to be effective; more color would make the result even darker. Toning with a lighter pigmented toner would give a muddy appearance and hide the figure unacceptably.

We hoped to avoid having to bleach the wood for several reasons.

By removing the sealer and topcoat with solvent, we were able to test whether we could remove sufficient color to be able to adjust with other stain or toner to the desired range. We could not. We determined that the coating could be removed with acetone or lacquer thinner and the surface sanded to remove the dye color. We could then use a washcoat of sealer to reduce the absorbency of the end grain to uniform the effect of the dye. Further uniforming could be performed with an aerosol dye type toner.

I cautioned him to apply the topcoat in thin coats and to dry each coat thoroughly before applying another, as he felt he had to rush to get enough lacquer on the surface to allow him to wet-sand and polish to a high gloss. I also advised him to use a safe heat source to speed the drying.

I had the opportunity to see the piece several days later. Here’s what I observed: The scratches were less in evidence, although a few of the deeper ones were still detectible, but not very objectionable. The color was much more even and not so strong and dark. The sheen was duller, probably in the 65-75 gloss units range, and steel-wool scratches were visible in low-raking light. In that light, depressions of approximately 1-2 mils depth and ½” in diameter were discernible.

I questioned him about what he had done. He explained that when he was sanding the wood, he hand-sanded, without a block, many of the deeper scratches. He knew that that would make the surface somewhat irregular, but figured that with enough lacquer he could level that surface when he did the final sanding and polishing. However, the lacquer in the depressions continued to shrink after he sanded it level. When he did the polishing, they became more evident, so he decided to rub with steel wool and a lubricant. He was not sure of the grade; when we looked, I determined that it was 2/0, which was too coarse for the purpose.

The missing link

What was the most important step he left out? My answer was the step panel.

The wise finisher will prepare a step panel before beginning to finish his laboriously produced woodworking masterpiece and a corresponding finishing schedule.

The finishing schedule is a written record of all that you’ve done, or plan to do, to apply a finish to your work. It can be very simple or quite detailed, depending on the finish and your own needs. It helps you to reproduce the finish later; troubleshoot if something goes wrong and, in a complex finish, help ensure that you perform all the steps you’ve planned. For a novice finisher, it is often helpful to use a recipe tried and tested by others to guide you as you perform that finish.

A step panel is wood of the same species as the furniture, divided into sections that show each step of the finish. It is one of the most effective procedures to help the finisher predict the outcome of a finishing schedule or step; maintain consistency between one piece and another and head off problems before committing to the entire piece.

To make a step panel, apply a piece of masking tape, ¾” wide or more, (typically from the bottom up) horizontally across the panel. Then perform your first step to the entire surface (in this example it would be the dye stain) then apply another piece of tape just above the first, perform your second step (wood stain for this panel) on the rest of the surface. Tape this off and perform the third step and so on until all the steps have been performed. When the step panel is complete and the tape removed, the board shows what the wood will look like after each step. This gives the person performing this step something to compare to as an aid in making every piece of furniture passing through that station identical.

Sometimes, a target color is represented by bracketing; one board with the lightest acceptable color and another with the color that is the darkest acceptable. The finisher applies the right amount of stain, glaze or toner, or wipes off the right amount of stain or glaze to keep the coloring in between the two.

You can make step panels in your shop even if you’re doing all the steps in the finishing schedule yourself. Just as in a factory, a step panel is especially valuable when trying to make a number of objects come out identical. A step panel also helps you figure out the sequence of steps on something other than the piece itself that will produce the appearance you want.

In the example cited here, making a step panel prior to executing the entire finish, with its deficiencies, could have alerted the finisher to problems before they were compounded by subsequent steps.

Greg Williams, formerly senior touchup and finishing instructor for Mohawk Finishing Products, is now a freelance instructor and consultant.

This article originally appeared in the August 2016 issue.

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