Graining: Creating a Wood Grain Effect

Graining is a method of colouring wood with paints to resemble the appearance of natural woods. Graining is done by coating the surfaces with a suitable ground colour which is followed by the application of a special stain preparation known as ‘scumble’. The colour of the ground or base should be suited to the colour of the scumble, which is obtainable in a very good range of shades similar to the colours of natural wood. The correct colour for the ground coat, in relation to the colour of the scumble being used, is printed on scumble containers; also it is given on manufacturers’ colour cards.

The preparation of surfaces for graining, which is especially suitable for front doors, is the same as for painting. Any repairs to the woodwork should be carried out, the old surface cleaned down with sugar-soap and glass-paper, any bad surfaces burnt off and scraped, bare knots primed, and bare patches and holes and cracks coated with priming.

 

After the priming has dried, the surfaces being grained should be rubbed down with new grade middle-two glass-paper. The work is then stopped and filled in the usual way, as described above, using putty for deep holes and cracks and powder-filler for small surface imperfections. The work should be well dusted after the filling has been rubbed down, before the undercoats of ground colour are applied. The composition of the ground-colour undercoats is the same as those for ordinary painting, and no special undercoats are necessary. In most cases two undercoats should be sufficient; each one should be allowed to dry and harden before rubbing down preparatory to applying the next coat.

The graining may be done in several ways. Graining may be done with metal combs with teeth of different widths. Simulating the grains of some woods entails the use of these combs and wiping with a cloth.

Graining may also be done with graining rollers which have embossed wood-grain patterns, and by using sheets of very thick paper which are embossed with a wood-grain pattern. All the graining tools, etc., are used after the scumble has been applied, and while it is still wet and soft.

The DIYer interested in this area of decorating may experiment and become proficient with any of the graining devices described above. There is, however, another method of graining painted woodwork which the DIY-decorator will find extremely easy to carry out. In this method the freshly applied scumble is given a grained texture with a dusting-brush, or a clean dry paintbrush of suitable width — say 3 in. or 4 in.

Whatever method of brush-graining is decided on, the inexperienced decorator should first test the method on unobtrusive surfaces, or on pieces of waste materials in the workshop. Graining of all kinds can be practised on odd pieces of hardboard. The scumble is applied with a paint-brush and for most jobs a 1-in. brush should be sufficient. The scumble is prepared ready for use and merely requires stirring before brushing it on. The drying action of scumble is such that the inexperienced person should have sufficient time to pattern and mark the soft scumble before it sets off. If, however, yon finds that the scumble sets too rapidly the drying action may be slowed down by mixing a small amount of linseed oil with the scumble. The drying action may oppositely be speeded up by mixing a small amount of turpentine or white spirit with the scumble. Any additives should be well stirred into the scumble before using it.

A small amount of the scumble is brushed on to the surface being treated — the method of application is similar to that of painting and the sequence of work is the same in that edges should be coated before areas are filled in, etc. The scumble should not be applied too thickly and it is not necessary to lay it off. With the section of the surface under treatment coated with scumble the graining-brush is brought into use.

The first action of the brush is to use it with a tapping movement to stipple the scumble and spread it evenly over the surface. The area should be treated methodically, working from one end to the other in the direction of the brush handle, and the brush should be raised cleanly from the work as each light tap is made. With this done the tips of the bristles should be wiped on a dry cloth, and the scumble-coated surface is again gone over with the graining-brush. This time the brush is drawn over the surface with the bristles held fairly flat on the work. As the brush is drawn through the scumble it is moved quickly from side to side with very short undulating movements — about in. each way is sufficient. When this is done the bristles drag through the scumble to reveal irregular streaks of the ground colour and the finish is very much like a wood grain. The rest of the work is done in the same way. The graining is always done from corners or edges towards the centre of the section of work under treatment. If a mistake is made, the soft scumble should again be worked over to stipple it with the ends of the bristles, before again re-dragging the brush through the stain. A short time spent in practising this very simple action will soon give the handyman-decorator the feel of the process.

The other graining devices are used in much the same way. The ground coat is brushed with a scumble which is stippled with the ends of the bristles by tapping the soft stain. If a comb is used, this is dragged over the surface of the work and the side-to-side movement of the comb should be the same as a graining-brush. A graining roller is merely rolled over the work and graining papers are pressed on to the soft scumble and the back of the paper rubbed over with a cloth. Each tool used for patterning the scumble should be wiped on a piece of cloth before re-using it for the next section of work.

Some very attractive finishes can be made in this way and the methods of graining may be combined to produce some very effective results. For instance, the roller, comb or graining paper may be followed by a very light dragging with the graining brush to imitate some wood grains, particularly oak, and small patches of the scumble can be wiped off with a dry cloth before using the graining-brush. The scumble should be allowed to dry before being finished.

Finishing consists of coating the surfaces with varnish to protect the scumble which, although dry, is still too soft to stand up to normal handling for any length of time. The varnish used for coating scumble should be oil varnish, and it is usual to apply two coats of egg-shell varnish which has a dull soft gleam when dry. This is followed by a glossy varnish.

27. July 2011 by admin
Categories: Paint Effects, Painting | Tags: | Comments Off on Graining: Creating a Wood Grain Effect

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