1st. It should be clear toned without muddiness.
2d. It should be very transparent.
3d. It should be heavy enough to brush out well, so that it may be combed and its edges remain clean cut without running.
35. The first requisite of “clearness and richness” in the umbers, siennas, ivory blacks and Vandyke browns ground in oil, which are used to prepare the megilp, is not so very difficult to obtain when the goods of well-known color firms are employed, but the second requisite, while it belongs to a stronger or lesser degree to all the colors enumerated, is far short of that which is required in a graining color.
36. To obtain the proper degree of thinness required, all the above colors would have to be thinned with linseed oil and turpentine far beyond that consistency which it is required to carry in order that it may be wiped and combed with well defined edges which do not run or blur. Therefore some perfectly transparent material must be added to it in order to give it this consistency. The material used for this may be rotten stone or whiting, or both, or china clay, or better, silicate earths—any transparent earth with no coloring of its own. Some grainers use putty thinned down with oil, but that is not so good as whiting, as the putty may be made of anything and the oil used in preparing it may be injurious to the durability of the graining.
37. Some of the old-time grainers used to prepare what may be called “stock megilp,” a portion of which they added to the oil colors as needed. Wm. E. Wall says of it “that the formula is this: Take 8 ounces of sugar of lead and 8 ounces of rotten stone, grind them together as stiffly as possible in linseed oil; then take 16 ounces of white beeswax, melt it gradually in an earthen pitkin, and when it is fluid pour in 8 ounces of spirits of turpentine; mix this well with the wax, and then pour the contents of the pitkin on the grinding stone to get cold. When cold grind the rotten stone and sugar of lead with the wax and turpentine and it will form an excellent megilp, which if kept in a jar with a mouth wide enough to admit a palette knife and secured from dust will keep almost any length of time.”
This is well and good for professionals, but it will hardly appeal to the ordinary grainer. He can grind up a little whiting and rotten stone and melted beeswax in turpentine and add enough to his color to answer his purpose.
With the present system of buying all colors as near ready for use as possible, color manufacturers prepare special oil graining colors ready for use by simply thinning. They come ready for all sorts of woods, and where the color is not just the shade wanted, the operator can easily add the one that is lacking to bring it to the right tone.
QUESTIONS ON LESSON VII.
33. What is said in a general way about preparing graining colors, or megilp?