In a recent number you published a formula for making a varnish unchangeable by any ordinary intrusion of water (as I would understand you). According to my experience of twelve years in such matters, I submit the following. Although in this instance I do not know what you mean by gum and water colors being so susceptible to the ruinous action of water, as there are so many kinds of gum, yet I presume you had reference to a spirit varnish containing a gum resin and any of the ordinary colors used by painters. I would state that according to my observation no spirit varnishes will stand the wet for a long time, and much less an aqueous solution of gum resins by an alkali. You will remember that water, potash, and shellac were at" one time much used to stiffen |iat bodies, and the compound went by the epithet of patent stiffening. My first hat happened to have it in, and unfortunately got caught in a shower, and ever after had the appearance of the fur en a recently drowned rat. The gum re-dissolving penetrating the silk. I have always found that oil and turpentine solutions of the gum resins, particularly copal, withstand the action of water and moisture best, but a varnish made of 8 lbs. gum damar, dissolved in 2 j gallons of spirits of turpentine is an excellent preparation for indoor work, or an article somewhat better but more expensive can be made as follows :mdash;5 lbs. mastic, 4 oz. white bees wax, 2 gallons of spirits of turpentine. Mix carefully ia a covered vessel subjected to a moderate heat. The addition of wax is intended to correct the brittleness of the varnish when dry, both useful as paint lustres. The pigments used in the preparation of water colors are mostly admissible in the manufacture of colored resin varnishes, some being clear while others are more or less opaque and are not easily affected by water if their particles are protected by a good varnish. With regard to the new varnish, the only advantage I can see in the use of lime with the potash is to render the latter more caustic. Yours, JNO. H. RASER. Reading. Pa., Jan. 1st, 1853. [The lime and potash make a caustic ley as alluded to by our correspondent. We are much obliged to Mr. Raser for his thoroughly practical information. The Delaware and Raritan Canal Company are about commencing the enlargement of their canal. The whole line is to be made wider and deeper, and new locks built throughout, capable of passing vessels of five hundred tons burthen ; making it, in reality, a ship channel. From four to five thousand men will be employed upon it, including many carpenters, masons, and blacksmiths. Fine tooth combs are now made of India rubber. Thefts of statuary have recently occurred in Greenwood Cemetery.
This article was originally published with the title "On Varnishes" in Scientific American 8, 18, 137 (January 1853)