Facts Worth Mentioning
FACTS WORTH KNOWING.
The Poisonous Effects of cyanide of potassium upon sores, may be obviated by immediately applying some of the positive developing solution, described at page 62. By this means much annoyance may be avoided to persons afflicted with chapped or sore hands.
Bending Glass Rods or tubes can be easily done by subjecting them to the blaze of a spirit lamp—the same as that used for gilding the daguerreotype. First hold the rod just above the blaze, then gradually allow it to descend into it, imparting to the rod a rotatory motion with the finger and thumb: this will soon cause a softening of the glass, when it may be bent to any desired shape. If the ends are to be bent to form hooks, another small piece of glass, or any warm metal, may be placed upon the end, in the blaze of the lamp, and as soon as thoroughly softened, it can be pressed or bent to form the hook. By filing around a glass tube or rod, it may be easily and safely broken at the desired point, by giving it a sudden jerk between both hands, holding it close to the encircled part.
Cementing Glass may be readily accomplished by placing the two ends together in the blaze of the lamp, and holding them there until they attain a sufficient degree of heat to slightly fuse: when cool, the ends will be found perfectly united.
The Background best adapted to positives is unbleached muslin, such, as is sold for sheeting, and can be found in almost any dry goods’ store: it should be from two to three yards wide. A clouded appearance is given to the background by merely marking it with charcoal, forming streaks or “waves” resembling clouds. These come out black, or dark, in the positive, and give a variegated appearance. The roughness of the marking does not matter, since the background is generally a little out of the focus of the lenses. Trees and other designs may be represented in this matter.
Positive Collodion Pictures may be whitened by the use of bichloride of mercury, thirty grains to one ounce of water. After the picture has been developed, fixed and washed, by the process given in the preceding pages, the solution of bichloride of mercury may be poured over the surface of the image: it almost immediately presents a series of interesting changes in color. The surface at first blackens but for a few minutes, when it begins to get lighter, and gradually brightens to a pure white, inclining to a blue. It should then be thoroughly washed and dried, as usual.
Instantaneous Pictures may be taken by employing the iodide of iron in the collodion. The best method with which I am acquainted, is to have a saturated solution of iodide of iron in alcohol, and drop one or two drops into an ounce of the collodion (which has been previously iodized) used in taking positives. This can be used at once, as soon as mixed. No more of this collodion should be prepared than is wanted for immediate use, as it will keep good for only a few hours. The saturated solution of iodide of iron can be kept on hand ready for use at all times. There should be an excess of the iodide in the alcohol. The same accelerating effect is produced with the negative collodion prepared in this way.
Plain Collodion may be iodized as soon as dissolved: this will save time in settling. It is a fact that some cotton is more readily dissolved when the bromo-iodizing is present: but by the addition of this, I have often taken up considerable quantities of the gummy sediment remaining in the bottom of bottles.
Prepared Glass may be preserved clean and free from dust by keeping in boxes such as those used for keeping daguerreotype plates. By taking out every other partition between the grooves, the glass can be readily put in.
Collodion Vials and Bottles, after having collodion in them once, should be rinsed with alcohol and ether (in the same proportions as employed for dissolving the cotton), before using them a second time for that purpose. Penuriousness in this respect would be bad policy.
Coating Large Glasses.—A convenient method of doing this is represented in the following illustration:
The glass is held by one corner, 2; the other corner, 4, is rested on a table or bench, and the collodion poured on, so that the excess may be poured off at 1.
Black Stains upon the hands, caused by nitrate of silver, may be removed by moistening them and rubbing with a lump of cyanuret of potassium. This salt is poisonous, if used to a great extent [See page 139]. Another safer, but more expensive plan, however, is to take a saturated solution of iodide of potassium in water, and then wash with nitric acid diluted with two parts water.
Stains upon White Linen can be removed by washing with a saturated solution of iodide of potassium containing a little iodine; then wash with water, and soak in a saturated solution of hyposulphite of soda until the yellow iodide of silver is dissolved.
The hands should always be washed after fixing a positive or negative picture, before again touching a glass to be coated, or the dipper; this precaution is necessary, lest any of the iron salt, or the hyposulphite, should get into the silvering solution and spoil it.
In taking Collodion Pictures, it is always advisable for the sitter to be arranged before the glass is taken from the bath: this will save time and there will be less liability of the collodion drying.
A Good Negative may be known by its possessing the following characteristics:—By transmitted light the figure is bright, and appears to stand out from the glass; the dark shadows are clear, without any misty deposit of metallic silver; the high lights black almost to complete opacity.
A Glass Coated with Collodion, if kept too long before immersion in the bath, will not be equally sensitive over its surface; the parts most dry being the least sensitive.
Glass Pans, for Scales, can be procured by every one at trifling expense: Take a watch crystal, and place in the common metal pan; balance this with lead, or any weight: this can easily be kept clean, and is the most advisable for weighing all deliquescent salts, and chemicals employed in the collodion process.
Caution.—Persons engaged in making collodion, and using ether and alcohol, must bear in mind that these chemicals are very inflammable; hence extreme caution is necessary to avoid exposing them to the flame of a lamp or candle. I have known of several serious accidents, of recent date, all of which were caused by the imprudence of the experimenter in the particular above mentioned.
Wipe the Plate-holder every time before the glass is put into it: this will prevent spots, which might otherwise occur from the presence of nitrate of silver solution which drained from the plate previously used. These spots are of an opaque yellowish tinge, and in shape resemble the stain which would be occasioned by a splash of water.
Glass jar Positives.—A good white or light-green glass will answer for the collodion coating. Glass which contains air-spots can be used, if it be placed in such a manner as to let the light of the image come over them, as the spots cannot be seen through the opaque surface. Only the best white glass should be used for covering the picture. Some operators use the convex glass, which is very clear, and answers the purpose.
The Nitrate of Silver Bath should be kept covered, except when in use.
If a Glass be Immersed too soon, streaks and waves will be occasioned. These will be seen at the end of the plate which is least dry: the coating is also more liable to peel off. It should be borne in mind, however, that the peeling of collodion is not always attributable to this cause.
Diffused Light in the Developing Room.—In proportion as the sensitiveness of the plates increases, greater care must be exercised in thoroughly excluding all rays of white light. With opalescent films, neutral, this cause of fogging is more common than any other.
Tn the case of a portrait, if the features have an unnaturally black and gloomy appearance, the dark portions of the drapery, &c., being invisible, the picture has been underexposed in the camera.