This is an excerpt from “To Make as Perfectly as Possible: Roubo on Marquetry” by André-Jacob Roubo; translation by Donald C. Williams, Michele Pietryka-Pagán & Philippe Lafargue.
If a perfect knowledge of the different colors of wood is essential to a cabinetmaker, he must also distinguish these same woods by means of their nuances, or better said, by the different shapes that the tints of the fibers represent, in order not to use them without choice nor knowledge of their character.
Woods, with regards to the conformation of tints of their fibers, can be considered as making four distinct species, one from the other. They are: those of which the concentric layers are alternately tinted in diverse colors but of a large and irregular manner, as you can see in Figs. 1, 2 and 3. The first one represents a piece of wood of which the concentric layers are tinted at unequal distances, which produces similar stripes on the grain line, Fig. 2, split according to the direction of the stripes of the tree. If on the contrary, one splits them parallel to the concentric layers, like in Fig. 3, this wood is only a single color more or less dark, according to which the split is made in a vein more or less light, which makes these sorts of wood not normally used except on the quarter-round cut, as in Fig. 2, or cut diagonally, as indicated with line A–B, same figure.
The second type of wood, with regard to their grain patterns, are those of which the concentric layers, although distinguished by color at the end grain, like in Fig. 4, produce no stripes along the grain, but simply singed veins or spots, like those in Figs. 5 and 6. These sorts of woods are very nice when they are well chosen and used with discernment, by reason of the size they will occupy and a comparison being made with that of their nuances or their spots, which are always more abundant on the radial cut than on the concentric layer.
The third type of wood is those of which the end is veined irregularly in all ways, like Fig. 7. These species of woods are most likely being used on end grain or diagonally, as I observed in Figs. 8 and 9. As to the grain line, it is hardly an effect except on the quartersawn, where the colors must be vivid, which is quite rare in these sorts of wood.
The fourth type of wood is that where the concentric layers are regular and alternating in various colors, like that of Fig. 10. These sorts of wood are those where one uses with the best advantage, because not only are they beautiful on end grain, but also along the grain line, whether they are split parallel to the concentric layers, as in Fig. 11, or according to the direction of the rays, like in Fig. 12. In the first case, they present a wavy surface, where the spots or singes [area of lightness or of disorder, representing a flame] are more or less large according to the split being made closer to the circumference of the tree. In the second case, that is to say, when the split is made on grain, as in Fig. 12, the wood presents stripes almost regular, which are more or less perfect according to the split being directly made when in the center of the tree.
These four types of differences, which concern the tints of the wood, are those that are the most striking, because there is an infinite number that are but variations between those which they resemble in some areas.
— MB