I built the cabinet from maple to save money. Now it was time to try to darken it to the middle-toned mahogany finish our friend wanted. I knew I didn’t want to use a pigment stain on maple. I thought a dye stain could work, but I really wanted to use water-based poly toned with dye. I thought it would be easier to apply than other options, and I could control the depth of color by applying more or fewer coats.

I’ve used TransTint dyes before (as a stain, not a toner), and I showed our friend the TransTint color chart. She liked the brown mahogany color the best.

To test the dye as a toner, I mixed it with General Finishes High Performance Water Based poly (flat finish) in a 1:64 ratio. When I applied it to a test piece, I could immediately see something was amiss. The mixture was pulling and coalescing into circular depressions (fish-eyes).

When the finish dried, the color looked good, but there were light spots throughout the finish.

I didn’t know if the flattening agents in the poly were interacting with the dye, if I was using too much dye, or if there was another cause. I wrote to TransTint, and their reply was that they’d never seen TransTint cause fish-eye, that there must be some contaminant in either the wood or the poly, and that I should test with and without the dye on other pieces of wood. I finished a random scrap from my bin with the poly, and it was fine.

Instead of running a lot of other toning tests, I decided to try applying the dye as a water-reduced stain (not a toner) and top-coating it with poly. That worked better. I still saw some circles in the wet and drying poly, but nowhere as many as I had seen before.

When the poly dried, I didn’t see the light spots I had seen in the toned sample. I decided to give this approach a try on the interior surfaces of the center cavities.

I tested several concentrations of the dye and settled on a mixture of 1 teaspoon of dye per 4 ounces of water. I applied the mixture liberally, spreading it evenly with a foam brush, and wiped off almost no excess. I just worked the brush back and forth to even out the color and make sure there were no puddles. That approach yielded a nice, mostly even color.

Encouraged by that result, I continued with the poly. I applied the first coat very quickly, because I knew the water-based poly was going to reactivate the dye and, in the worst case, lift enough of it to cause pale areas. After that coat dried, I lightly sanded it with 320-grit paper and added two more coats. The results were acceptable. The color was good and mostly uniform, and the surface was smooth. (The plywood back panels were paler and blotchier, but I expected that. I was afraid to sand the very thin surface veneer, and there wasn’t much material for the dye to penetrate.)

Upon closer inspection, the finish showed a slight orange peel effect. You can see it in the bright section of the front shelf below. The surface felt smoother than it looked (in raking light).

That result was good enough for the center cavity. Most of it is hidden by the drawers, and the open cavity is so small and dark that the orange peel is hard to see. It wasn’t going to be good enough for the cabinet’s outer surface, though.

I decided to apply a seal coat of shellac over the dye before adding the poly (something I should have done from the start). I wanted to spray it with rattle can shellac (Zinsser Bulls Eye), but the instructions say not to use it as a seal coat under poly. (There also seems to be disagreement on the web about whether it’s wax-free or not.) I decided not to tempt fate and bought a quart of Zinsser SealCoat (wax-free shellac, 2 lb. cut).

The problem with SealCoat is that I didn’t have any denatured alcohol (and didn’t know where to buy it) to use to clean a brush, and I didn’t want to ask my wife if I could use one of her brushes as a sacrificial brush. (She’s the painter in the household.) I decided to try wiping it on.

I decided to try this new finishing approach on the least visible surface, the cabinet bottom. The dye looked good, as before.

I quickly wiped on two coats of the shellac with a blue shop towel, then sanded it smooth. I think brushing would have been easier, but wiping worked well enough. The only problem I had is that, if I left a puddle or spilled a large drop on the surface, it seemed to dissolve part of the dye, leaving a light patch.

The poly went on very smoothly over shellac. As a bonus, I needed only two coats of poly instead of the three I had planned. The shellac took the place of the first coat of poly, which is basically a sealer coat anyway.

At this point, I decided to pre-finish every surface except the top. (I didn’t want the clamps I’d use during the case glue-up to damage the finish.) That involved tedious taping of the areas to receive glue later, but it went well.

I installed the drawer slides and glued the center assembly together before finishing its outer surfaces (the inner surfaces of the cabinet’s side cavities).

After the poly dried, I would be ready to glue the case together.