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.
What Lead To Use. The beginner will find a moderately hard lead the best to employ, as his touch will be somewhat heavy, and if a soft lead is used the pencil strokes will show and too much of the lead will be deposited upon the negative. An HHH lead will be more suitable for the beginner, yet, if with this there is any trouble experienced, due to the lead adhering to the negative and the lines showing too strongly, it would be advisable to procure and use an HHHH lead. Those who have had any experience in drawing, or in fact any work requiring technical skill in controlling the hand, will find the HH lead most suitable, for their touch of hand is light. Those inexperienced are very apt to work with a heavy hand and an HH lead would be too soft, and a harder pencil, say, an HHH, will be more suitable for them, until they learn to acquire a lighter touch. If the lead takes too freely, you will know the lead is too soft for your touch and a harder pencil must be used, and vice-versa. One should practice using as light a touch as possible, for the softer the pencil employed the more work you will accomplish in a shorter time.
Sharpening The Lead. The proper manner in which to sharpen the lead for retouching is fully explained in the lesson, but if difficulty is experienced, or if the lead breaks off before a sharp point is obtained, the trouble will invariably be due to (a) your holding the pencil the wrong way; (6) bearing on too hard, or (c) moving the lead in the wrong direction. To sharpen the pencil to a perfect point, have fully an inch of the lead protrude beyond the holder. Then (a) hold the lead at an angle with the sand-paper or emery-cloth so the taper will extend from the point to the holder; (b) bear on the pencil with only enough weight to keep it on the sharpening block; and (c) rotate the pencil between the thumb and fingers, at the same time moving it lengthways, not sideways, of the lead. A movement to the side will in almost every instance cause the point to break off. To produce a fine, smooth point after sharpening on the sand-paper, rotate the lead on a piece of newspaper, or paper having a similar surface.
Retouching Medium Not Working Properly. (a) If you have carefully followed the instruction for mixing up the retouching dope or the retouching varnish, you should experience no difficulty in having the lead adhere to the negative. When using the retouching dope composed of balsam of fir and turpentine, should the lead not adhere add a sufficient amount of resin to give a tackiness. About 1/4 ounce of resin to 2 ounces of dope will give you a very desirable tooth, (b) If the dope is too thick, i. e., if the stopper has been left off the bottle, the turpentine will evaporate and leave a very thick substance which cannot be spread properly on the negative and will not, therefore, hold the pencil marks to the film. The dope should be thinned with turpentine until it is of proper consistency.
 
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