INDIARUBBER AND GUTTA-PERCHA MENDING INDIARUBBER SHOES AND MAKING GARMENTS WATERPROOF, WITH OTHER APPLICATIONS

Indiarubber or gutta-percha enters into so many familiar and useful objects that there are few people who would not like to know how to repair them when injured.

Like the brittle or non-elastic gums, caoutchouc (with which I include the nearly allied gutta-percha) is greatly modified by admixture with certain pulverised substances, which form with it a partly mechanical, partly chemical, combination. Those who would thoroughly study the subject in all its relations may consult Kautschuk (Caoutchouc) und Guttapercha, von Raimund Hoffer; Wien, 1892, Hartleben.

Caoutchouc is partially soluble in carburetted sulphur, ether, pure petroleum, or benzole, but gutta-percha is perfectly so. In this state it may be applied as a varnish or coating for repairs, as it hardens by exposure to the air. When mixed with sulphur and exposed to a heat of 110° to 115° centigrade, gutta-percha becomes what is called “vulcanised,” assuming a very light grey colour, is more elastic, and retains this elasticity at a much lower grade than before. When the heat is raised to (maximum) 180° the mass becomes very hard, tough, and black, or like horn. The conditions of its toughness, elasticity, and hardness depend upon the amount of sulphur used; as in other combinations, the harder the material becomes the less elastic it is—that is, the more brittle.

Ebonite is extremely hardened caoutchouc. It is first treated with chlorine, washed with sulphate of soda infused in water, and finally mixed with hardening substances and submitted to severe pressure.

As indiarubber or “gum” shoes are in general use, most people would consider them the proper objects to begin with. To do this, first make two separate preparations as follows:

I.

Caoutchouc 10

Chloroform 280

II.

Caoutchouc 10

Resin 4

Turpentine 2

Oil of turpentine 40

No. I. is simply kept for a time in a bottle or tightly closed jar by itself. No. II. is made by cutting the gum very fine, mixing it with the resin, then adding the turpentine, and finally dissolving the whole in the oil of turpentine. Then combine I. and II. To repair the shoe, take a linen patch, steep it in the mixture, and place it over the rent. When this is dry apply one or more coats.

It may be observed that this preparation may be used not only for indiarubber shoes, but many other objects. Applied to the soles of leather boots, and then heated in, repeating the process a few times, they become perfectly waterproof. This is better when the shoemaker makes a coating of it between the two soles. I have tested this often. The inner sole may be made by simply dissolving the indiarubber in benzole or ether. A solution for ordinary repairing can be made by simply steeping the indiarubber in benzine.

Rents or holes in ordinary leather shoes or other objects can be very well repaired in this way. A piece of leather can in this case be substituted for the linen rag. Boots or shoes which will be very much exposed to wet should be warmed and then soaked or permeated with a solution of indiarubber. Preparations for the purpose can be bought of all dealers in gum and gutta-percha.

Cloth is generally waterproofed by steeping it in a slight solution of caoutchouc.

Another recipe (Lehner) is as follows:—

Caoutchouc 150

Tallow 10

Slacked lime 10

This is used to cork or close bottles. To render it more resistant, substitute pipeclay for the lime. Or if in place of either we use red oxide of lead, it will form in time an extremely hard and perfectly waterproof cement of great value.

A strong indiarubber cement:—

Caoutchouc, about 90

Pulverised sulphur 10

Or from 6 to 12 of the latter.

This is specially commended as useful to close tins containing fruits, &c. It is simply vulcanised indiarubber.

Marine glue is a very valuable and generally useful cement. It is so called because, being perfectly waterproof, it is used for many purposes in ships. It is applicable not only to repairing indiarubber or gutta-percha garments, but also to objects of metal, wood, glass, stone, paper, or cloth; as, for instance, umbrellas, on which, when torn, a patch or strip of silk or muslin may be gummed, which will last as long as the rest. It is also good for waterproofing shoes. It is sold by dealers in ships’ stores, chemists, and others. “It is a good thing to have in the country.”

Hard marine glue:—

Caoutchouc 10

Rectified petroleum 120

Asphalt 20

To prepare this, the caoutchouc should be hung in a linen bag in a cask with a very large bung, or in a large jar, so that the bag shall be only half immersed. This is kept in a warm place for from ten to fourteen days, till the solution is effected. Then the asphaltum may be melted in an iron kettle. Let the rubber solution slowly run into the kettle over a gentle heat, and stir in the one to the other till the mass is thoroughly preserved are put in the bag; the edge is then turned incorporated. When this is effected pour the mixture into moulds which have been oiled to prevent adhesion. The result is dark brown or black thin cakes, which are broken with difficulty. The excellence of this cement is somewhat counteracted by the difficulty or care which must be observed in using it. To do this, put the vessel in which it is to be melted in another or a balneum mariæ, as for glue, filled with boiling water. When fluid take the kettle from the fire and subject it directly to heat till it attains a temperature of 150° centigrade. When it is possible, heat the object to be glued to 100°. The thinner the coat and the hotter the surface the better will it adhere, unless the objects be such as hard boards. In all cases as strong a pressure as possible should be employed to bring the two parts together, which should be continued till the glue has dried. Boxes which are cemented together by means of marine glue and are also nailed are of extraordinary strength, and may be thus made air-tight and waterproof. Those who intend to send articles which can be affected by sea-air, such as silks and tea, which change their colour and quality even when packed in the tightest ordinary cases, should employ boxes well secured with good marine glue. It is also invaluable to secure clothing against moths, for if anything be very thoroughly dusted and there are no moths in it, none can get in if it be enclosed in a box rendered air-tight.

Apropos of which I would say that in America moths, which are far more of a pest than in Europe, are effectively excluded by means of bags of strong paper, well tarpaulined or tarred. The objects to be over and warmed, so that it seals itself up. Strong paper bags are better than any trunks to exclude moths, but they must always be well gummed up. Tobacco is no protection at all against these insects. I have even had an old woollen Turkish tobacco-bag which had been in use ten years, and which was partly full of tobacco, almost devoured by moths, which must have eaten no small quantity of tobacco in so doing. Nor is camphor or any other scent half as effective as hermetic closing in some substance which insects will not eat.

Lehner gives a suggestion regarding the rendering walls air-tight which is of such remarkable practical utility that it ought to be enforced by health laws in every house. Whenever walls have any tendency to absorb dampness—and all have it in damp weather, especially in underground rooms—it is far more dangerous than is generally supposed to put paper on them. This is so much the case that where workmen, from carelessness, paste one coat of paper over another on a damp wall, the mass in time gives out a very poisonous exhalation, so that an instance is recorded in which several people died, one after the other, in consequence of sleeping in such a room. To prevent this take the following waterproof cement:—

Caoutchouc 10

Washed chalk 10

Oil of turpentine 20

Bisulphide of carbon 10

Resin (colophonium) 5

Asphalt 5

These are combined in a large flask, kept in a moderately warm place, and often shaken till well incorporated. The wall to be covered should be brushed and wiped, and in some cases heated, until extremely dry. Then, using the cement, apply the paper in the ordinary way. It will stick with great tenacity, this being a very tight and strong glue. All wall-paper whatever is more or less productive of malaria in damp weather, as is the smell of a damp library, or one where the scent of old paper is rankly and offensively perceptible. Therefore every precaution should be taken to render it innocuous.

Even if no paper be applied, this cement is very valuable when simply used to coat the interior or exterior of damp walls. It can, of course, be used to repair many articles of indiarubber, and to mend shoes, tan garments, &c. Apropos of which latter I may here remark that all persons who intend to rough it in the bush as colonists, or go into any region where mending or getting mended is difficult—as I myself have many a time experienced—would do well to carry a tight tin box of waterproof glue, with which torn shoes, and very often torn clothes, can be promptly repaired. In fact, with the aid of a little rough stitching, or even without it, garments of leather, muslin, and even of cloth can be made to hold together with certain cements, which will literally bind anything.

It is well worth while for those who propose to live in the wilderness, wherever it may be, to know how to prepare or make indiarubber garments. The recipe is very easily made:—

Gutta-percha 10

Benzine 100

Linseed-oil varnish 100

The gutta-percha is dissolved in the benzine; the solution, when clear, is poured into a bottle already containing the varnish, and all is then thoroughly shaken. This mixture, when spread on woven fabrics of any kind, renders them completely waterproof. The garments can then be cut out and “sewed;” that is, bound together with the same cement. According to Lehner, this cement can be used for making the soles of shoes, and is marvellously elastic. All travellers, and assuredly all housekeepers, should have this cement among their possessions.

It may also happen to a traveller to find himself with an aching hollow tooth in a region where no dentist is accessible. Should he have with him some gutta-percha (bleached is best for this purpose) he may combine it with very finely pulverised glass. (To levigate or powder anything as fine as flour, it must be pounded in a mortar, or on metal or hard stone under water.) Then warm and thoroughly mix the gutta-percha and glass. Make it into little pencils, which, when they are to be used, must be dipped in hot water. This cement may be also used for a great variety of other purposes.

A very admirable cement, which should be found in every stable and known to every one who owns a horse, is made as follows:—

Hartshorn and resin ammoniacum (Ammoniakharz) 10

Purified gutta-percha 20-25

Heat the gutta-percha to 90°-100° centigrade, and thoroughly incorporate it with the powdered resin. The chief use of this admirable composition is to fill up cracks or splits in horses’ hoofs. It may also be used for plaster on occasion. To apply it to hoofs, warm it and spread it in with a warmed knife. It sets so hard that it will hold nails.

In mending or making, it may be observed that a very little indiarubber or gutta-percha may be combined with benzole or ether, or rectified petroleum in large amount, which soon becomes dense. Therefore, to produce a surface or a skin, we first spread a thin coat over the object or mould, and then apply another with a broad, soft brush or “dabber” with great care, so as to make it of uniform thickness. It is, therefore, best to have the preparation always rather thin, and use it at the right time, and not when it has become dense by long keeping. In the latter case add more of the solvent.

Glass bottles or vials containing liquids are often broken, even by the pressure of soft objects, such as clothing, when placed in trunks. It is therefore advisable to dip or coat them with this solution, which forms a bag which will contain the fluid; that is, unless it be of a nature which will soften it. I have known a bottle of hair-oil to be packed in a valuable cashmere shawl, which was almost ruined by its breaking, and which could have easily been prevented by this easy precaution.

Any apothecary will make up these recipes.

A very curious and valuable imitation of indiarubber waterproof cloth is made as follows:—Caseine is macerated with water and with borax to a solution. The cloth is dipped in this, and when quite dry, again dipped into a strong infusion of gall-apples. This is a kind of tanning.

For exhaustive information on the subject of indiarubber the technologist may consult Kautschuk und Guttapercha, by Raimund Hoffer, Leipzig, 1892, which is, I believe, the latest and best work on this important subject.