Sunday, April 27, 2008

Finishing Experiments

Ash has very porous grain which must be filled before coating in order to quickly obtain a smooth surface. Without filling the grain, the top coats will just soak into the grain making it difficult to get a glassy finish. I'm using Bartley's Wood Paste Filler and blue dye powder purchased from the Guitar ReRanch.

During the past week I've done some finishing experiments. I managed to get grain filler on the scraps, and some stain and sanding sealer as well. The short version is that I've decided not to stain the wood blue as I attempted in these experiments. Instead, I''ll use dark grain filler to get the high contrast effect and spray a translucent blue color coat after applying the sanding sealer.

Here are the scraps with various stages of grain filler applied.

The two outside pieces on the far left and right have the natural grain filler applied-- it dries translucent so the pieces look very close to the natural wood. The middle three were treated with darkened grain filler -- a mixture of one spoonful natural grain filler to 15 drops of Minwax ebony stain, which produced a very dark gray, almost black filler. The two pieces on the left did not get a wash coat, while the three on the right did (four passes of Deft clear gloss lacquer aerosol). The piece second from the right has been sanded after a single application of grain filler. It exhibits the desired high-contrast grain effect. You can see some blue splotches it -- some of the stain jumped out of the container as I mixed it.

I mixed the blue dye power in lacquer thinner and applied it directly to some of the wood after grain filling and sanding. The three right most pieces below also have a few coats of sanding sealer applied.

Staining the wood after grain filling and sanding didn't work out as well as I had hoped. It appears that the washcoat, the grain filler, or both, interferes with the stain even though the wood was sanded back. The color is uneven next to the grain filled areas - there is a very thin area of natural wood color that follows the grain pattern. I may try this technique with a piece that didn't get a washcoat to see how it works out. The use of lacquer thinner as the solvent also appears to be a problem. Even after several coats of sanding sealer I can see the grain pattern in the surface when viewed at a low angle. The lacquer-thinned staining step appears to have affected the integrity of the grain filler. On the piece that was not stained, the sanding sealer appears perfectly flat.

I might be able to get better results if I had mixed the dye with alcohol instead of lacquer thinner. This is an experiment I will probably try in the future, but for now I've changed my plan to include spraying a blue translucent color coat over the sanding sealer rather than staining the wood directly. The piece above does show the look I'm after, but I want a darker blue and a more even application of color. I could mix and spray the color using the dye powder I have on hand but I'd have to buy a spray gun and a can of regular lacquer (I've got lots of aerosol at the moment). So I opted to order a can of blue translucent aerosol from the ReRanch instead.

My next step will be to apply the darkened grain filler to the body... Check back soon.


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