age or stain cherry sapwood?

[morganew]

I've just made a cherry version of the Roycroft "Little journeys" book shelf. The top is made of two 7" wide pieces of cherry, but both have a little sapwood on them. I was planning on "baking" all the piece in the sun this week before finishing with BLO and then either shellac or spray-can lacquer, then hand rub with some 000 steel wool and wax. I know that sapwood doesn't tend to darken as much as the heartwood, but how big a difference will I see? will BLO help, and should i do that before sunning the pieces?

I'm very new to the finishing world, so I am open to suggestions on all fronts here.

[Bob Rozaieski]

If you want the color to match, you'll need to blend it with a dye, toner or glaze. I've had good success doing this with woods that don't change color much over time, or tend to lighten slightly (like walnut). The big problem with cherry (as opposed to something like walnut) is that the heart wood in cherry will continue to darken over time while the sap wood, color matched or not, will stay the same. So even if you match the color of the sap wood to the heart wood perfectly today, in a year, it will be different again as the heart wood will have continued to darken and the colored sap wood will stay the same, or possibly even fade depending on the method chosen to do the color match. For this reason, while I will tone the sap wood in walnut, I tend to prefer to leave the sap wood in cherry alone, or if everything must match (and continue to match as the piece ages), I remove the cherry sap wood when building the piece.

With that said, if you want to blend the color of the sap wood with the surrounding heart wood now, I've found toners and glazes to be better and offer more control than a dye or stain. I've never been really happy with the results of blending sapwood using dyes. This is probably because dyes and stains will penetrate the wood and if you get it too dark, you will have a lot of trouble reversing it because of this. Toners (colored shellac basically) and glazes on the other hand are films that sit on top and can be lightened by applying them thinner or darkened by adding more color to them or applying more coats. Toners are easily made by using blonde shellac (Seal Coat works well as it is a very thin cut) and adding alcohol soluble dyes like TransTint to it. You can experiment by adding different amounts of different colored dyes to the shellac in order to get the color you need. Glazes are typically made using oil based gel varnish and oil based pigment colors (the kind used by artists to do paintings). Glazes work really well to add depth and age to a newly finished piece. For blending sap wood, I think shellac based toners are easier to use though.

Basically, you would go ahead and oil the entire piece like you want to. Once the oil is dry, apply a wash coat of blonde shellac to the entire piece (again the Seal Coat works well). Once the wash coat has dried, knock down any dust nibs with some 400 grit paper or steel wool. Then begin to do the toning of the sap wood. It should go without saying, but I'll say it anyway because it is so important; EXPERIMENT ON SCRAP FIRST. While it isn't the end of the world if you don't, because shellac can be removed with alcohol, it is best to work out your coloring on scrap before doing the actual piece to avoid a lot of extra work. Also, write down how much of everything you mix together each time you try a new toner combination so you can recreate and/or scale the mixture up when you find the combination that works. Once you have a combination that works well to blend the colors, use a small artist brush to apply the toner to the sap wood areas that need blending. Once the sap and heart wood colors are blended to your satisfaction, you can topcoat with whatever you want, as shellac is pretty neutral to any kind of topcoat (the same cannot be said for oil based glazes).

The nice thing about these shellac based toners that you make yourself is that in the future when the cherry heart wood darkens significantly past the toned sap wood, if the color difference bothers you, you can rematch the sapwood areas to the darkened heart wood by making up a new batch of toner (albeit probably a different color combination) and reapplying it to the lighter areas, then lightly retopcoating again.