This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
Baths are made of the following materials: copper, sheet-iron, cast-iron, steel, zinc, slate, fire-clay, marble, wood, and wood lined with lead.
Of the various kinds of metal used for baths, copper is undoubtedly the best and most durable, as also it is unquestionably the most expensive. A well-made copper bath will bear re-enamelling many times over, and when finally discarded, the metal will always fetch a fair value. An iron bath, on the other hand, when worn out, is worth little more than the cost of removing it.
Baths of tinned sheet-iron, copper, or zinc, are made in two ways; either they are made of thin sheets of metal, which require the support of a wooden framework or "cradling"; or they are made of sufficiently stout metal to stand alone without support. The latter are known in the trade as Roman baths, and, from the point of view of cleanliness, possess manifest advantages over the lighter and less expensive forms which require cradling.
A bath which requires the support of cradling: must also be cased; that is,. the exposed side or sides of the rough framework must be concealed by wooden panelling*. The space thus inclosed under and around the bath is generally inaccessible for at least half its extent, and. as the framed inclosure and top are as a rule ill-fitting, becomes a harbour for dirt and rubbish of all descriptions If a bath must be inclosed, and, as already explained, there are Borne advantages in doing this, the framing should be made of hardwood, as dust-proof as possible. and the top (also of hardwood) should be bedded on the top edge of the bath in hardwood.
Roman baths, on the other hand, need no casing, and if made (as they generally are) with a large roll on the top edge, do not require a wooden top. They can and should be fixed clear of the walls, so that access can be had to both sides for the purpose of cleaning. These baths can be had with the taps so arranged that they are entirely self-contained, and can, if need be, be fixed in the centre of a room.
Another advantage of the Roman type of hath is that the metal tray or "safe" underneath must be dispensed with, and accordingly the overflow has to be so arranged that the safe is not needed. The safe, it should be explained, is a metal tray about four inches deep, placed under a bath so that all water leaking from the bath, or overflowing the top of it, may be caught and carried away by the tray, and not escape on to the wooden floor and so through to a ceiling below. These safes are apt to become extremely offensive from various causes. They are frequently laid flat, and not infrequently with a fall in the contrary direction to the outlet; with the result that, when water is suffered to overflow, it remains in the Safe instead of running away. If the water is soapy -as of course it frequently is, - the dried soap will be left on the surface of the metal long after the water has evaporated, and the effect will be extremely unpleasant There is considerable variety in the shape of baths. They are either made to taper from head to foot, or are made parallel. They are made with sloping sides and head, or with perfectly straight sides and head; they are sometimes made partially covered over, or with a hood at the end for shower, douche, needle, and spray baths, or they are made with curved sides. The object of sloping the sides, bo that the bottom of the bath is narrower than the top, and of tapering the bath from head to foot, is to economize water. This arrangement is sometime, carried to such an excess, that the bath is uncomfortably narrow at the bottom. The head is sloped to give a more comfortable rest for the back of the person using the bath, and the foot end of the bath is sometimes covered in order to assist in retaining the steam. The hood arrangement will be described hereafter.
A point of importance is the formation of the angles of the bath inside. The junction of the bottom with the sides and ends should be rounded, in order to afford as little lodgment as possible for grease and dirt. This can of course be very readily done in a cast-iron bath, but in sheet-iron or copper the formation of these rounded angles is not so easy. In the stamped steel baths the curved form is also easily obtained, and is one of the most favourable points about this kind of bath.
The usual lengths of baths are 5 feet, 5 feet 6 inches, and 6 feet, but smaller sizes are made for use in nurseries, and have the advantages of economizing water, and of being rapidly filled and emptied.
The finishing of the surface of a metal bath can be arranged in several ways. In best work, both copper and iron baths are first tinned and then japanned or enamelled. The object of the coat of tin is to prevent oxidation and to give a ground for enamelling. In applying a coating of tin to iron, the surface of the iron is first cleaned by being turned to a bright polish in a lathe. This can only be done to comparatively small articles, and is impossible in the case of cast-iron Whs, which are made in one piece. The tinning in the case of the latter kind of bath is done by a process of dipping, first into acid and then into tin. Tin thus applied does not stand nearly so well as when it is applied to a bright surface, the adhesion not being so perfect The process of japanning copper baths, and enamelling tinned sheet-iron baths, is identical. The surface of the metal is first carefully cleaned, and painted with a specially-prepared paint, the base of which is zinc It is then subjected to a heat of about 300 degrees F. Before the next coat is applied, the bath is well rubbed down with pumice stone. It is then painted again and fired as before. There are usually three qualities of finish, the difference consisting in the number of coats of paint and firings applied; thus, "first quality" will usually mean a bath which has had four coats, "second quality" one which has had three coats, and " third quality " one which has had two coats.