PAINTING TIN ROOFS.
When paint scales from a tin roof it is not always the fault of the paint. It stands the painter in hand to carefully examine a new tin roof before painting it. When the tinner uses rosin as a flux to make his solder flow, the rosin is melted and cools again on the tin. When such is the case, carefully scrape it off with a knife, otherwise it will be liable to scale off, and take the paint with it.
When acid is used in the place of rosin it is apt to corrode the tin, hence it is best, if you want a permanent job, to clean off the acid. To do this, first rub the seams with kerosene oil, then wash with soap suds and rinse with clean water. If the roof is quite new, and the tin feels greasy, go over it with a wash made of one pound of sal-soda to six quarts of water, let it stand one-half day; then wash the tin with clear water.
Instead of this method, I have given new tin a good rubbing with No. 1 sandpaper to make it hold the paint.
ANALYSIS OF OCHRE.
Below is an analysis of a sample of French ochre, which is about the average of that pigment:
| Parts. | |
| Hydrated oxide of iron | 42 |
| Alumina | 20 |
| Silica | 38 |
The oxide gives the color; the parts as given above are in the right proportion to give the most stable color and durable body to be found in ochre.
Here is an ochre, which was ground in a linseed oil substitute, and sold to the trade at four cents per pound in twenty-five pound cans, and retailed to the painter at seven cents per pound in cans, to-wit: