This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Etching. Etching is exactly the reverse of retouching, for by means of the etching knife, which is a very sharp steel blade, the film is shaved or scraped in proportion to the amount required to be removed; thus high-lights are reduced, shadows accentuated, objectionable portions removed, and detail produced where the opacity of the negative was so strong as to destroy it.
Object Of Retouching. We have seen that the object of retouching and etching is to remove spots, blemishes and imperfections, and to model the portrait negative or perfect the landscape negative. The lens often sees more than the human eye. It may magnify imperfections which are unobserved on the natural object or subject. The ordinary plate does not reproduce the tonal values of the object, yet it is used for most all purposes, with the result that light blues reproduce white, yellow reproduces very dark, ruddy cheeks appear hollow, etc.
10. Many times the operator fails to correctly light the subject, and the false lights which will then exist must be removed and correct lights built up. The negative may be under or over-exposed, under or over-developed. There are times, also, when it is necessary to alter the expression - to remove a scowl, or to close an open mouth with teeth showing. The drapery may have to be changed and imperfections removed which the operator has failed to overcome. It is for these and many more reasons that retouching is necessary. The photographer, in making the negative, should aim to reproduce in the portrait the very best qualities of the individual, subduing the more undesirable features. If he has failed in this, his retoucher must do what he can to correct the oversight or deficiency.
11. Although few workers agree as to the exact amount of retouching required, all acknowledge that a certain amount is absolutely essential in order that the negative may be in perfect condition for printing. A certain class of workers contend that there should be little
more than enough lead applied to the plate to remove the most apparent predominating blotches and spots. Then, there are those who go to the other extreme and literally cover the negative solid with lead, retouching without any regard whatsoever for the modeling, or without even attempting to retain the likeness of the individual. It is their aim to idealize the subject. While this is permissible and can be accomplished by the judicious application of the lead and etcher, yet by over-retouching all character and expression of the face is lost. Judgment must, therefore, be exercised just as much in retouching as in any of the other branches of photography and a mean between these two extremes aimed at.
12. It is not only necessary to remove the transparent and more striking imperfections, but the entire face should be blended and modeled so that no harsh lines exist. Aim to secure a thin negative which will produce a print with excellent gradations between high-lights and shadows; a print that will retain all of the character and likeness of the individual. The general public demands considerable work on the portrait negative, but the retoucher must use careful judgment and not go so far with the pencil work as to destroy all likeness and flatten out and destroy the modeling.