Home › Adhesives, Paints, and Varnishes › Adhesives, Paints, and Varnishes: Paint

Adhesives, Paints, and Varnishes: Paint

PAINTS AND PAINTING Paint, including painting and the care of paints, is an important subject. Both the inner and outer walls and the floors of houses and most articles of furniture are painted.

Hence a knowledge of the nature and properties of paint, both before and after its application, enables it to be put to a thousand practical uses in the household. The uses of paint are twofold, i. e., to protect the wood and other materials to which it is applied, and also to decorate them. The ingredients of paint are of two sorts: the pigments or coloring matter, chosen mostly for decoration; and the vehicle chosen to hold the coloring matter in suspension, and also, when desired, to furnish the requisite protection. Linseed Oil for Paints. - The best vehicle for paints used to protect woodwork and other surfaces from moisture and decay is linseed oil.

This is one of the so-called drying oils which, on exposure to the air, absorb oxygen and form a resinous varnish that closes the pores and excludes the agents of destruction from all surfaces to which it is applied.

Thus it holds the pigments in a firm waterproof varnish.

Linseed oil is of two sorts: raw and boiled. The raw oil is of two grades: the cold-drawn and the hotpressed or ordinary quality. Raw linseed oil dries slowly, passing through a gummy or sticky stage before acquiring a hard, resinous surface. The object of boiling this oil with oxide of lead, peroxide of manganese, and borate or acetate of manganese is to cause it to dry more quickly. Boiling gives the oil a dark or high color. The raw oil is obtained from flaxseed by crushing the seed under great hydraulic pressure.

When the seed is not heated, the oil is said to be cold-pressed or colddrawn, and is of a light or pale color, but when the crushed seed is heated and pressed hot, the oil is darker. Much more oil can be extracted from the same quantity of seed by hot pressure. The colddrawn oil is therefore more expensive, but it is of a better quality. Pigments for Paint.-The pigments or coloring matter used in paints are prepared by grinding them in a mill and mixing them with a small quantity of raw linseed oil.

They come in small packages and are prepared for use by mixing them with an additional quantity of raw or boiled linseed oil and one or more colored pigments, ADHESIVES, PAINTS, AND VARNISHES which are mixed together to produce pared without oil by using as a vehiany desired shade. Thinners for Paints. - The various pigments mixed with oil alone would make too thick a coating; hence other ingredients known as thinners are employed to dilute them. These are oil of turpentine and benzine, which mix freely with linseed oil and various pigments, and reduce them to any desired consistency. Dryers for Paints. - Even boiled linseed oil does not dry quickly enough; hence to hasten the union of oxygen with the paint, which transforms it into a dry, hard, resinous substance, it is usual to mix paints with certain substances known as dryers. Among these are sugar (acetate) of lead, red lead, verdigris, binoxide of manganese, sulphate of zinc, etc. The most powerful dryer is boric manganese, even the Too part being enough to greatly hasten the drying of linseed oil. These and other dryers come ground in oil ready to mix with paint.

Ready-made Paints. -The materials used for paints for home use must be kept separate and not mixed until the paint is about to be used. Or, if mixed in advance, the paint must be covered with water and kept from the air. Otherwise the thinner will evaporate, the pigment will settle to the bottom, and the oil will become thick and ropy, forming a hard skin over the top which cannot be dissolved.

Hence paints are now mixed in factories on a large scale by a process which forms an emulsion or permanent mixture of the pigment and the oil, and these can be had in any size cans, the contents of which are always ready for use. However, anyone can obtain the necessary ingredients, pigment, oils, thinner, and dryer, and mix paints for home use at less cost usually than he would have to pay for the ready-made article, and with the further advantage of knowing precisely the nature and purity of all the ingredients employed.

Water-color Paints. - Paints for interior work, walls, ceilings, pictures, maps, and the like, are sometimes precle glue or gum dissolved in water. After the water evaporates, the glue or gum is left, and this causes the pigments to adhere to the surface.

The ingredients must not be mixed until ready for use, as glue or gum will not keep in solution for any length of time.

Calcimine is a paint of this character, being a mixture of prepared chalk with a solution of glue and various colored pigments.

Water colors can also be obtained in the form of cakes consisting of pigments and gum in solid form, which may be liquefied by dissolving in water or by rubbing them with a wet brush.