The Making Of Black Stain for Iron
For colouring iron and steel a dead black of superior appearance and permanency, the following is a good formula:
1 part bismuth chloride,
2 parts mercury bi-chloride,
1 part copper chloride,
6 parts hydrochloric acid,
parts alcohol, and
50 parts lamp-black,
these being all well mixed.
To use this preparation successfully—the article to be blacked or bronzed being first made clean and free from grease—it is applied with a swab or brush, or, better still, the object may be dipped into it; the liquid is allowed to dry on the metal, and the latter is then placed in boiling water, the temperature being maintained for half an hour.
If, after this, the colour is not so dark as is desired, the operation has simply to be repeated, and the result will be found satisfactory.
After obtaining the desired degree of colour, the latter is fixed, as well as much improved generally, by placing for a few minutes in a bath of boiling oil, or by coating the surface with oil, and heating the object till the oil is completely driven off The intense black obtained by this method is admirable.
Another black coating for ironwork, which is really a lacquer, is obtained by melting ozokerite, which becomes a brown resinous mass, with a melting-point at 140° F.
The melted mass is then further heated to 212° F., the boiling-point of water.
The objects to be lacquered are scoured clean by rubbing with dry sand, and are dipped in the melted mass. They are then allowed to drip, and the ozokerite is ignited by the objects being held over a fire.
After the ozokerite has burned away, the flame is extinguished, and the iron acquires a firmly adhering black coating, which resists atmospheric influences, as well as acids and alkalies.
If the black iron vessels are to contain alkaline liquids, the above operation is repeated.
A good cheap stock black paint or varnish for ironwork is prepared, as follows:
Clear (solid) wood tar, 10 lb.;
lamp black or mineral black, 11/4 b.;
oil of turpentine, 51/2 quarts.
The tar is first heated in a large iron pot to boiling-point, or nearly so, and the heat is continued for about 4 hours. The pot is then removed from the fire out of doors, and while still warm, and not hot, the turpentine, mixed with the black, is stirred in. If the varnish is too thick to dry quickly, add more turpentine.
Benzine can be used instead of turpentine, but the results are not so good. Asphaltum is preferable to the cheap tar.
To make another good black varnish for ironwork
,
Take 8 lb. of asphaltum and fuse it in an iron kettle, then add 2 gallons of boiled linseed oil, 1 lb. of litharge, 1/2 lb. of sulphate of zinc (add these slowly, or the mixture will boil over), and boil them for about 3 hours. Then, add 11/2 lb. of dark gum amber, and boil for 2 hours longer, or until the mass will become quite thick when cool.
After this it should be thinned with turpentine to the proper consistency.
You might Also see :