Scientific American 17, 15.1.1848
(Concluded from our last.)
The finishing part of Japanning lies in laying on and polishing the outer coats of varnish, which is necessary in all painted or simply ground colored japan work. When brightness and clearness are wanted, the white kind of varnish is necessary, for seed lac varnish, which is the hardest and most tenacious, imparts a yellow tinge. A mixed varnish we believe, is the best fro this purpose, that is, for combining hardness and purity. Take then thre ounces of seed lac picked very carefully from all sticks and dirt and washing it well with cold water, stirring it up and pouring it off, and continuing the process until the water runs off perfectly pure. Dry it then and reduce it to powder and put it with a pint of pure alcohol intoa a bottle, of which it must occupy only two-thirds of its space. This mixture must be shaken well together and the bottle kept at a gentle heat (being corked,) until the lac be dissolved. When this is the case, the clear must be poured off, and the remainder strained through a cloth an all the clear, strained and poured, must be kept in a well stopped bottle. The manner of using this seed lac varnish, is the same as that of using the other, and a fine polishing varnish is made by mixing this with the pure white varnish described in a previous article. The pieces of work to be varnished for finishing should be placed near a stove, or in a warm, dry room, and one cost should be perfectly dry before the other is applied. The varnish is applied by proper brushes, beginning at the middle passing the stroke to one end and with the other stroke from the middle to the other end. Great skill is displayed in laying on these coats of varnish. If possible the skill of hand should never cross, or twice pass over in giving one coat. When one coat is fry another must be laid over it, and so on successively for a number of coats, so that the coating should be sufficiently thick to stand fully all the polishing, so as not to bare the surface of the colored work. When a sufficient number of coats are thus laid on, the work is fit to be polished, which in common cases is commenced with a rag dipped in finely powdered rotten stone, and towards the end of the rubbing a little oil should be used along with the powder, and when the work appears fine and glossy, a little oil should be used alone to clean off the powder and give the work a still brighter hue. In very fine work, French whiting should be used, which should be washed in water to remove any sand that might be in it. Pumice stone ground to a very fine powder is used for the first part of polishing and the finishing done with whiting. It is always best to dry the varnish of all japan work by heat. For wood work, heat must be sparingly used, but for metals, the varnish should be dried in an oven, also for papier mache and leather. The metal will stand the greatest heat and care must be taken not to darken by too high a temperature.
When gold size is used in gilding for japan work, where it is desired not to have the gold shine, or appear burnished, the gold size should be used with a little of the spirits of turpentine and a little oil, but when a considerable degree of lustre is wanted without burnishing, and the preparation necessary for it, a little of the size along with oil alone, should be used.
I now conclude these articles on Japanning and Varnishing. A great deal more might be said, but this may be sufficient for the present. There are other mixtures that can be used, and there are some variety of opinions among practical men. What I have said may be old to some, but presume that much may be new to many and be of some benefit to not a few. At some other period I may again present some more information on the same or other branches in connection with this subject and shall endeacor to be as condensed, plain and practical, as I trust I have been. My honest endeavor at least, being a desire to bring out in public print, something relative to an important art which winds itself round a great number of different trades, and for which I have ever sought in vain for information in any work published in my own lifetime.