THE decorative effect of window shades is often disregarded, the selection depending on the momentary whim of purchaser or salesman. Almost without exception parsimony is practiced, even when the rest of the furnishing is on a generous scale. Yet the window dressing of a house has everything to do with the appearance of both interior and exterior. And of window dressing, except in metropolitan mansions, where draperies are elaborate, with lace next the glass and overhanging of tapestry, damask or brocade, the shades are one of the most obvious features.

In all decoration an important law is: "Avoid violent contrasts." If the shades are very dark or densely opaque, the contrast between the shaded and unshaded parts of a window, seen from the interior, is extreme - deep shadow above bright light. For during the day shades are commonly rolled up to leave the lower half or two-thirds of the window exposed. But if the shades are light in color and semi-translucent, the contrast is gentle and pleasing.

The color of the room is an important factor. Green shades in a red room, or red shades in a green room are an abomination, as are dark shades in a light room. But while the shades in a room with dark walls and furniture should correspond in tone, the contrast with the outdoor light must be kept in mind, and the shades should be lighter than the other furnishings. If the windows have small panes, or leaded and colored glass, the brilliancy of the light that comes through them is less, and there is less danger of too violent contrast with the shades and interior walls.

The night effect of the shades (when the source of illumination is inside the room) is economically as well as decoratively important. Dark shades and shades rough of texture reflect little light, so that if the windows are many and the shades completely lowered, the necessary cost of gas or electricity may be half as much again as with light, smooth shades. To leave the shades up only aggravates the evil, for clear window glass lets out practically all of the illumination that strikes it, and the windows are then black boxes against lighted walls - the most unpleasant kind of contrast.

Extreme contrast is also the most common fault in the exterior appearance of shades. From outside the house, light shades against dark walls, and dark shades against light walls, are equally distasteful. Unshaded windows are black boxes when seen from the outside - too black even by contrast with a house that has been painted dark, and aggressively ugly against light paint, as may be seen in the illustration below.

In hue the shades should harmonize with the exterior, red with red, green with green, and yellow with yellow, but as a rule, should be lighter in tone. Shades darker in tone look opaque and stand out against their background.

Some attention should be paid to the environment of the building. The colors and tones that dominate in the landscape invite representation and reflection in the shades, especially if their presence has already been appreciated by the house painter.

At this point some reader asks: "How reconcile the decorative demands of the exterior with those of the interior? What shall be done when the exterior is dark red and the interior is light green?" There is the rub. Duplex shades with red outside and green inside are sometimes suggested and used. This makes it possible to have shades that correspond on the inside with the different colors of half a dozen different rooms, and are all the same color on the outside. But duplex shades are necessarily opaque, and usually offensive. They are an attempt to solve a difficulty that should never have been created. In other words, the contrasts between interiors and exteriors should never be so strong as to call for shades of double face. If these contrasts are gentle, it is easy to find shading of intermediate color and tone. When in doubt, use gray, brown or light yellow.

I have emphasized the disagreement between reds and greens because it is the one that most often troubles, yet it is one that is regarded by many persons as harmony. However, reds and greens do not always disagree violently. They can be reconciled by toning them together. Light red against dark green is hideous, as is dark red against light green. Yet the contrast between light red and light green is pleasing. For in both the hue has been softened and toned down by the addition of white or gray. The addition of red to the green or of green to the red, or of some third color to both, also brings them together.

Of these facts the reader can assure himself by personal observation - unless he is colorblind. It is not necessary to accept the dictum of the decorator or the epigram of the faddist. It is possible by practice and experiment to acquire a working knowledge of light and color. The use of two sets of shades - the outer set opaque to shut out the light completely, the inner set translucent to tone the light agreeably - is the best solution of the whole problem. And if the light be also modified by leaded glass, or latticed sashes, or by net curtains next the glass, glare and shadow will be entirely avoided.