Produced from a variety of synthetic and organic mineral sources, stains are dispersions of particles of pigment within an oil or solvent base. This process may be able to yield the same color with only one operation.ĭyes are less light-fast than pigmented stains and in renovation work this can be used to an advantage. Oil- and solvent-based dyes may be added to pigment stains to form a combined stain and dye.
On a more oily wood, oil- or solvent-based dyes may penetrate better. For instance, with maple or birdseye maple, it may be found that water-soluble dyes penetrate more evenly across the whole surface. Each has a particular use in the coloring process. The four main types of dyes are: water-, alcohol-, oil- and solvent-based. With water-based dyes, as the water evaporates, the wood is left with only the color in its surface. In addition, dyes bind to the wood because of their chemical molecular structure and no additional binder is required. The molecular size of the dye particles is much smaller than that of mineral particles in stains, and thus dyes appear more transparent. In addition, dyes penetrate both the soft and hard grain, and often enhance or "bring out the grain." Dyes change the hue of the wood without hiding its figure or rendering the surface unclear or muddy. Modern woodworking dyes are very similar to those used for dyeing cloth, paper or leather. Colorants can be broken into two large groups: dyes and pigmented stains.ĭyes are a solution of colorants in mineral spirits, oil, alcohol or water. In many cases, it is appropriate to sponge the surface with water, alcohol or solvents to show any areas which may contain glue, marks, oil or uneven sanding. For this reason it is important to prepare samples with the actual grits and the actual stains and finishes.Īfter the wood has been well-prepared, it is ready for the even absorption into the wood - or absorption onto the wood's surface - of dyes, stains or fillers. For instance, the large valleys left by 80 grit sandpaper will absorb much more pigment than will the fine tracks left by 150 grit sandpaper. No matter how much sanding is used on these areas, they will never disappear.Ī stain's penetration also depends on the final grit with which the wood was sanded. Most North American diffuse-porous woods have small, dense pores resulting in less distinct figure and grain.Ĭertain closed-grain woods such as cherry and maple tend to develop finishing blotches caused by textured grain. Close Grain hardwoods, such as cherry, maple, birch, and yellow poplar, are "diffuse-porous" species. These species have distinct figure and grain patterns. Open Grain hardwoods, such as elm, oak, and ash are "ring-porous" species.
The cellular structure of a wood influences its appearance. The stain and finish then can be taken into the pores evenly across the whole surface. Indentations, grease, oil and other wood defects are removed with multiple grits of sandpaper, scraping, and even sponging and then sanding. The most important step in hardwood finishing is wood preparation.
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