WE cannot decide what type of enamel to choose until we know what materials are available, and for what purposes they are specially intended. Unfortunately, the term enamel is rather loosely applied to all kinds of super-finish and varnish paints, but the following are most likely to be of use to the handyman.
Super high-gloss enamel is still the best available finish where durability and a brilliant, lasting gloss is required. It is equally serviceable for interior or exterior work, and withstands plenty of washing without injury.
Bath enamel, as its name implies, withstands the action of soap and hot water.
Gloss enamel paints and hard gloss paints are frequently used for general house painting. They have several attractive features, the chief of which are: (I) a wide range of colours; (2) economy (they are only half the price of the super high-gloss type); (3) they have better obliterating power, and are calculated to save an undercoat; (4) the surface to be painted is more easily prepared when repainting becomes necessary; (5) like enamel, they are usually suitable for either inside or outside work.
As a rule, the two characteristics, gloss and obliterating power, are skilfully balanced by the manufacturer. It must be realized that high gloss is only obtainable by limiting the amount of coloured pigment, and as gloss is of greater importance in a finishing coat we must not demand perfect obliterating capacity. The undercoats should perform the duty of hiding all imperfections of surface. Gloss is imparted to the enamel by gums and residues of oils, while obliterating power is afforded by the inclusion of a suitable pigment, usually of an oxide specially suited to the purpose of the enamel.
Synthetic enamel paints or lacquers are similar to the above type except for the synthetic resin which forms an ingredient. Hardness, gloss, durability against weather, and quick-drying qualities are claimed for this class of paint, which is equally useful for a front door or a bicycle. An important point is to ascertain at the time cf purchasing whether the material can be applied over ordinary paint, or whether a special undercoat is necessary.
Floor enamels are useful for giving new life to old linoleum, or for brightening and dustproofing cement floors. Some varieties are also capable of resisting heat, petrol, and oil. No undercoating is required for this product.
Cellulose enamels dry so quickly that only small areas can be satisfactorily dealt with unless a spraying plant is employed. They are too inflammable to be used near an open fire and usually require a special undercoat. The room temperature should be approximately 70 degrees F. when applying cellulose enamels. On no account must they be used upon recently applied oil paint. Cellulose finishes present that hard, smooth, surface found on motor cars, etc. If extensive work is to be undertaken with this enamel, try to arrange suitable ventilation so that fresh air is blowing the odour away from the face.
Bituminous enamels are water-resisting compounds, ideal for the proofing of concrete or Portland cement, or as protective coatings for gutters, rainwater pipes, garden railings, and ironwork exposed to weather or in contact with earth. The insides of cold water tanks and cisterns are often painted (when dry) with these compounds. A possible snag connected with their use is their liability to discolour a top coat of ordinary paint if this is applied at some future time without a special undercoat. Flat enamels (non-glossy) are available for interior walls and woodwork. They present the smoothness, hardness, and freedom from brushmarks so characteristic of gloss finishes.
Preparation of Enamels
The only safe rules to follow are those laid down by the manufacturer, but in the absence of other instructions, these materials should not be thinned or interfered with in any way, otherwise loss of gloss will invariably follow.
With undercoats it is different. A very dull gloss forms the ideal surface upon which to apply the finishing enamel. Thin coats build up the hard, smooth surface required, and it is usually necessary to add genuine turpentine or a really good substitute, as a thinning medium. On no account should paraffin or inferior grades of white spirit be used; their greasiness prevents proper adhesion and drying.
The amount to purchase can be calculated by roughly measuring the area to be coated and working on the basis that one pint of enamel (or undercoating) covers ten square yards. In terms of weight, this means that one pound of material covers approximately six square yards.
Before the application of any form of paint it is better to know what conditions are most likely to ensure success. A well prepared surface will be perfectly clean, smooth, hard, and dry, and these conditions are usually present only on new work.
Previously painted work has first to be rubbed down (wet), with either a flat piece of pumice stone, or waterproof glass-paper. Then the work is well rinsed with clean water and dried with a washleather. Should the old paint be cracked or blistered, it is more quickly and easily removed by blowlamp or gas burner jet as described in HOUSE PAINTING.
Paint will neither dry nor adhere properly when applied to a dirty or greasy surface. Furthermore, it causes flaking off and cracking of subsequent coats of new paint. Any roughness of surface becomes exaggerated by a gloss finish and also accumulates dust and dirt. Dryness is of paramount importance; to paint upon damp surfaces invariably causes blistering.
Walls coated with distemper or hung with wallpaper must be soaked, scraped, and washed down with clean water, and defective plaster must be made good . When dry, the surface is treated as new plaster, I.e. glasspapered and given a thin coat of paint containing plenty of linseed oil to check excessive porosity.
Preparation of New Woodwork
After glasspapering woodwork, but before painting, all knots must be painted over with either patent knotting or shellac varnish to prevent them showing through and discolouring the finished paintwork. To be painted in that order.
Undercoating fulfils the important duties of completely checking all porosity, levelling and generally improving the surface painted, obliterating old paint, and giving the right colour for the reception of the enamel. The number of undercoats required varies according to the finishing colour. White enamel often necessitates four coats, while dark shades (upon old work) only need one undercoat.
Filling Nailholes and Cracks
On old work, this job is best done before undercoating, but on new work, after the first coat is dry. Linseed oil putty is commonly used, but a mixture of four parts putty to one of white lead forms a better stopping which leaves a smooth surface when dry brushes are also essential. These should not be so soft and springy as those required for undercoating, but stiff enough to spread the less easily manipulated enamel. Part-worn brushes, thoroughly washed in hot water and soap, are ideal for the purpose.
The enamel must be stirred well and then tested out upon the cupboard shelves, window frame, or other small area, in order to get acquainted with the different brush technique required. Enamel is never easy to apply. It must be more slowly and forcefully brushed, and at the same pressed firmly into place with the putty knife . Larger cavities may be filled with stopping.
Applying the Enamel
-Either a bathroom or kitchenette provides a variety of subjects suitable for enamelling. The ceiling and upper parts of the walls could be finished in cream coloured flat paint, and the dado (lower part of wall), door, window, and cupboards, in enamel (salmon colour). The skirting and door casing would then look well in black enamel. The bath may exhibit several rust spots and need renovating with the proper bath enamel.
The important essential in all this work is cleanliness, and all dirty work, including the scouring of the bath interior by pumice and washing of the floor, should have been completed, and the final undercoating applied, before any finishing colour is put on. Clean, time more generously applied, than paint.
To obtain a perfectly even gloss and colour, the coating must be spread evenly; this can only be accomplished by varying the direction of the brush strokes, working firstly in the direction of the grain, until about two square feet is evenly covered, then brushing across the grain, and finally finishing off with the grain of the wood.
The adjacent section is immediately joined up to the first and the work continued in the same manner until completed. All brushmarks should disappear within fifteen minutes, and any runs which may have formed should then be levelled out with the brush. Apply less material to mouldings; especially at the mitres, where it is liable to accumulate.
A door is coated in sections. Finish the dado. Leave the door casing and skirting (because of the wide difference in colour) until the following day, when the paler enamel should have dried out sufficiently.
Enamelling the Bath
The proper enamel and its undercoat-are obtainable in quantities sufficient for one large bath, but where undercoating is not available, mix 1 J lb. Of white lead with equal parts of carriage varnish and turpentine, until an easy-brushing consistency is reached; finally, sieve through fine muslin. Touch up those parts of the bath which are in any way discoloured; repeating the process (one coat each day) until the bath is of fairly equal colour. The whole surface will then require two or three coats to produce the perfectly even whiteness upon which to enamel. No glasspapering is to be done after the final undercoating lest the surface be soiled. Hang jars or tins over the taps to prevent drip and enamel the bath in progressive sections. Four or five days should elapse before using a freshly enamelled bath, and then, for the first few occasions of its use, run in cold water before running in the hot, thus avoiding the effects of excessive heat during the hardening and drying period.