The same colours as those of landscape painting are used for transparencies, and the processes are also the same; only it is requisite to be very attentive in washing in the tints with the utmost possible correctness, both with respect to form and to the power of colour, as the surface of the paper must be preserved clear in every part, and this clearness is always more or less injured by washing out or sponging. The paper should be the thinnest hand-wove drawing paper that can be procured, carefully selected, and free from unevenness or inequality of texture. When the paper has been selected according to the size of the proposed subject, it should be laid on a drawing board and fastened there, with a piece of thick paper beneath, in order that the tints may be distinctly seen during the painting. After having completed the subject so far as relates to the front, it may be cut off, leaving a margin 1/4 inch in breadth, for the purpose of gluing it down in the following manner. Take a sheet of Bristol-board, or if the subject is larger, a thicker material, for the purpose of preserving the surface of the whole even and flat. From the centre of this board let a piece be cut out corresponding with the size of the painting, which must be placed on a drawing board, with its face downwards.

Let it then be covered for a few minutes with a damp cloth, to cause it to expand a little; and in the meanwhile cover, with thick gum or glue, the edges of the aperture in the board, to correspond with the width of the margin cut off with the painting. The damp cloth may now be removed, and the painting turned with its face upwards, placing the board upon it accurately, in such a manner that the margin may adhere securely to the gum or glue in every part. The whole may then be laid on a flat surface to dry. In this way the Bristol-board will form a frame of such width as may be adapted to the painting, and this frame may be afterwards ornamented according to the taste or fancy of the student. It may be observed that the brilliancy of a transparent painting will be increased by the opacity of the border by which it is surrounded, and its width should be regulated by the size of the painting. As soon as the whole is thoroughly dry, the painting must receive such additions at the back as may be requisite to bring it up to the full luminous effect intended. For this purpose, the most convenient position will be one inclined similar to an artists' easel, and immediately in front of a steady light.

When the painting has been placed in this position, it will immediately be perceived, that however strongly it may have been previously tinted or touched in the front, a strong light will cause it to appear comparatively feeble. But as the original intention of the workman will still be impressed on his mind, this weakness in the effect, which only becomes apparent by transmitted light, will suggest the addition of tints to produce the intended power. Where more is required, it must be cautiously applied at the back of the painting, taking all possible care to preserve the colours clear, and not to injure or ruffle the texture of the paper, repeating the tints till the due power is obtained. When considerable power is required, such colours of Indian red, Cologne earth, or vermilion, must be selected as have a semi-opaque body; but care must be taken not to lay them on so thickly as to produce blackness. When richness is required, lake, Prussian blue, and gamboge, which are perfectly transparent, are well adapted to communicate not only richness but delicacy and power to finish.

When, by carefully employing the means just pointed out, all possible harmony and effect have been imparted to the painting, it may be rendered partially or wholly luminous, by judiciously applying mastic spirit varnish. With a camel-hair pencil moderately charged with this varnish, let such parts as are in the highest lights be carefully touched, as well as the major part of the sky, and the principal objects of the piece, together with whatever part may require it, in accordance with the character of the scene. If the whole of the subject is covered, it will be requisite to spread the varnish with a flat camel-hair brush, passing it quickly from side to side, and from top to bottom, so that the varnish may be equally spread with all possible expedition. The picture must then be left to dry. After the varnish has become dry, by mixing a little ox-gall in the water used for the colours, additional beauty of tint, as well as harmony, may be imparted to such parts as appear crude or harsh.