WASHING Clothes a Problem in Temperatures
Laundering has been done the world over ever since fabrics have been used for personal or household purposes. The aim has always been the same—to get out all the dirt and to get back the original color or whiteness without injury to the fabric. Many methods have been tried, in all countries, with varying degrees of success, from the primitive rubbing on the stones of the river bank to the modern washing machine.
The principle of all washing consists in sending a cleansing liquid through the clothes with sufficient force to dislodge the dirt. How hot shall this cleansing fluid be? This is an important question and when answered as the result of scientific study will go a long way toward working out a standard home-laundry method. For this reason the studies being undertaken at the present time by the department are emphasizing washing temperatures.
Before choosing the proper washing temperatures, a study must be made of the properties of soap, the characteristics of the common textile fibers from which fabrics are made, the kinds of soil that get on fabrics in everyday use, and the fastness of dyes to washing.
Friction and water are not enough to extract dirt from fabrics because loose dirt is held by a film of grease. Soap is needed also because it has the power of wetting greasy surfaces and of attracting to itself the dirt and grease, leaving the fabric clean. In order to act as a detergent, or cleanser, the soap must be dissolved in water. This is one of the reasons the temperature of wash water is important. Soap will dissolve at low or high temperatures depending on the kind of fat which was used in its manufacture. The vegetable fats usually produce soaps which can be dissolved in cool water and are so-called oleic acid or soft-oil soaps. Soaps made from animal fats, the so-called tallow soaps, generally require hot water to dissolve them. The temperature of wash water, however, does not depend alone on what will dissolve the different kinds of soap. Some of the textile fibers from which fabrics are woven are affected by water of different temperatures. Before buying the soap for laundering, therefore, it is important to know whether clothes can stand very hot water.
The fibers which are used most extensively in the manufacture of textiles may be divided into three classes: (1), The animal fibers, including silk and wool; (2), the vegetable fibers, cotton and flax; and (3), the artificial fiber, rayon.
The animal fibers belong to a group.of substances known as proteins and are soluble in an alkaline solution and injured by high temperatures. Wool is a slender, wavy fiber composed of elongated cells and covered throughout its varying length of three-quarters of an inch to 8 inches with minute overlapping scales. This peculiar structure of wool causes it to become felted when rubbed, or washed in very hot water or an alkaline solution. Silk, on the other hand, does not consist of a number of small cells, but is one long round filament., If unbroken in winding off the cocoon it may be as long as 40 feet. Tt does not shrink like wool, but is somewhat sensitive to heat and alkaline solutions. These properties of wool and silk suggest careful handling in laundering fabrics of these fibers, use of a neutral soft, oil soap, and need for lukewarm water for suds and rinses.
The cotton fiber comes from the fruit pod of the cotton plant and is three-quarters of an inch to 3 inches long. Under the microscope it looks like a twisted ribbon. Linen is made from the flax plant and the flax fibers are longer than cotton, varying from 12 to 36 inches in length. Flax fibers look like a straight ribbon with cross markings when examined with a magnifying glass. Both cotton and flax are made of cellulose and are not hurt by boiling water or weakly alkaline solutions. More drastic treatment can be used in washing fabrics of these fibers than is possible with silks and woolens. Brisk rubbing and stirring, a tallow laundry soap, and hot water can be used to good effect on cottons and linens.
Artificial silk, which is becoming more and more popular for undergarments and, in combination with other fibers, for dress fabrics, requires a certain care in laundering. It swells and loses strength when put into water and alkaline solutions. Therefore artificial silk fabrics must be squeezed rather than rubbed to remove the soil, and a neutral soap dissolved in lukewarm water used for suds and tepid water for rinses.
A colored fabric made from any textile fiber always causes greater anxiety in washing than anything white. How it is going to come out is oftentimes a gamble. Recently, however, great steps forward have been made in dyes and dyeing, and colored fabrics have been produced which are more likely to launder well. Still it is universally known that colored goods must be separated from white goods in laundering and treated as gently as possible while getting them clean. The general rule is to use neutral soap suds no hotter than lukewarm, followed by rinses of the same temperature, and to wash and rinse as quickly as possible. The hotter the water, the more of the dye will be stripped from the fabric by the soap suds.
The kind of soil on clothing also has to be considered in deciding on the proper temperature for washing. Excluding stains, which have to be treated aside from the regular laundry process, there are four kinds of dirt: (1) Albuminous matter, as for example, eggs, blood, or any body excretion; (2) finely divided matter, as soot and dust; (3) animal and vegetable fats; (4) machine and mineral oils.
Albumin is the only one of these which is changed by a temperature between that cf an ordinary room (70° F.) and of boiling water (212° F.). At a temperature about midway between these two, albumin changes to a form which will not dissolve in water, or becomes “set” on the fabric. The water for washing is generally somewhere between room temperature and boiling. If clothes have on them perspiration or other body excretions, or: bits of food containing albumin, there is danger that these may be “set” or cooked into the fabric if the water is hotter than this halfway point. Very hot water may be needed, however, to remove other kinds of dirt. If this proves true, in the study now under way, then a preliminary soaking in lukewarm water will be recommended in order to get rid of the albuminous dirt.
In studying these various points on washing temperatures, pieces of different fabrics are being soiled and then washed in small cylinder washing machines with different degrees of hot and cold water. The cleanliness of the fabrics is determined by weighing and by the use of an instrument called a photometer. The results of all these studies will be translated into a standard method for home laundering which will take out some of the guesswork and make washing possible in the easiest, quickest, and most efficient way.