Manufacturer and builder 9, 1872
[444] Testing Japan Varnish.
Good Japan mixes well with raw linseed-oil. Poor qualities do not mix well; therefore, all you have to do is to try this with a small quantity. It is best to use a piece of glass, and try to mix the Japan and oil with a small stick. If it does not mix well, do not use that Japan for fine work.
[446] Bleaching Flannel.
Soak for an hour in a weak solution of bisulphite of soda, then add a little diluted muriatic acid, stir well and cover the vessel for twenty minutes. After this, take the flannel out, rinse in plenty of soft. water, and dry in the sun.
[449] Lead Paints on Tin Roofs.
Lead paints do not form so reliable a protection for metals as earthy or ochreous paints containing iron and alumina. The best roof-paint is the mineral impure red oxide of iron, similar to burnt ochre mixed with linseed-oil. See further our January number for this year, query 278, page 24.
[450] Substitute for Lead Glazing.
The recent Industrial papers report that a German potter has succeeded to entirely remove the subtle poison from his establishment. He takes two parts of common fusible brick-clay, and one part of ochry-clay, (strongly impregnated with iron,) and works it with twenty-four parts of lye from wood ashes, to the consistency of cream. A thin layer of this liquid serves for glazing. The heat required for its fusion is greater, but as the manipulation is considerably simplified, and the vessels resist perfectly the action of acids, the results obtained are quite satisfactory, in addition to the great benefit conferred upon the operatives.
[456] Varnish for Silver and Brass.
The varnish universally used in this country for brass is simply a solution of shellac in alcohol, colored with some yellow dye, in order to give tho brass a less pale and more rich color. It is put on very thin, while the object is hot; for silver, either polished or flosted, the best varnish is collodion, of the kind photographers call plain collodion, diluted with some alcohol, and put on the warmed silver or plated object with a fine flat brush as a very thin coating. The latter will not change the color of the object in the least, nor will it allow the silver to tarnish.
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