Scientific American 16, 8.1.1848
For the ScientificAmerican.
(Continued from our last.)
Black grounds for japans may be made by mixing ivory black with shellac varnish, or for coarse work, lamp black and the top coat ing of common seedlac varnish.
A common black japan may be made by painting a piece of work with drying oil (oil mixed with lead,) and putting said work into a stove not too hot but of such a degree, gradually raising the heat and keeping it up for a long lime, so as not to burn the oil and make it blister. This process makes a very fair japan and requires no polishing.
Tortoise Shell Japan.
This varnish is prepared by inking or good linseed oil one gallon and of umber half a pound, and boiling them together until the oil becomes very brown and thick, when they are strained through a cloth and boiled again until the composition is about the consistence of pitch, when it is fit for use. Having prepared this varnish, clean well the copper or iron plate or vessel that is to be varnished (japanned) and then lay vermillion mixed with shellac varnish, or with drying oil diluted with good turpentine, very thinly on the places intended to imitate the clean parts of the tortoise shell. When the vermillion is dry brush over the whole with the above umber varnish diluted to a due consistence with turpentine, and when it is set and firm, it must be put into a stove and undergo a strong heat for a long time, even two weeks will not hurt it. This is the ground for those beautiful snuff boxes and tea boards which are so much admired, and those grounds can be decorated with all kinds of paintings that fancy may suggest, and the work is all the better to be finished in an annealing oven.
Painting Japan Work.
The colors to be painted are tempered genrally in oil, which should have at least one fourth of its weight of gum sanderac or mastic dissolved in it, and d should be well diluted with turpentine, that the colors may be laid on thin and evenly. In some instances it does well to put on water colors or grounds of gold, which a skilful hand can do and manage so as to make the work appear as if it was embossed. These water colors are best prepared by means of isinglass size mixed with honey or sugar candy. These colors when laid on must receive a number of upper coats of the varnish we have described before.
In our next we shall treat of the finishing of japanned work.