第11章

Coloring Back Grounds--Transparent ditto--Gilding Dissolvent Solution for removing Specks--Solarized Impression--To Purify Water--Cleaning Mercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax for Bottles--Rouge--Rotten Stone--Potassa Solution--Hyposulphite Solution--Substitute for do.--Gilding Solution--Solution for increasing the Brilliancy of the Daguerreotype--Bleaching Solution;--Cold Gilding--Neutralizing Agents--Buff Dryer--Keeping Buffs in order--Cleaning Buckskins--Reflector for taking Views.

To Color Back-grounds--To obtain a properly colored back ground is a matter of no little importance to the Daguerreotype operator.

I had nearly exhausted all patience, and tried the skill of painters to obtain a back-ground that would be suitable to my purpose;but all to no avail. At last I adopted the following method, and at a cost of coloring of twenty-five cents, can now produce a back-ground far more valuable than those which had cost five dollars before.

Take common earth paint, such as is used in painting roofs;mix this with water to about the consistency of cream;then to four quarts of this mixture add about one pint of glue water (common glue dissolved in water, also about as thick as cream).

This last will cause the paint to adhere to the cloth, to which it is applied with a common white-wash brush.

By applying the brush on the coating while it is wet, it may be so blended that not a line can be seen, and a perfectly smooth color of any shade can be obtained.

The shade of color I use is a light reddish-brown. Tripoli, rotten-stone, or any earthy matter, may be applied in the same manner.

Transparent or Invisible Back-ground.--I give this as originally published in my System of Photography, 1849:

"Take a large woollen blanket with long nap, the longer and rougher it is the finer will be the effect produced;stretch it on a frame of sufficient size, and suspend the frame at the centre of the upper end by a string fastened to a nail in the ceiling, from three to five feet back of the sitter.

Having arranged this, fasten another string to the side of the frame, and while the operation is going on in the camera, swing the back-ground from right to left, continuing this during the whole time of sitting, and you have a clear "transparent"back-ground, which throws the image out in bold relief, and renders the surface of the plate invisible.

If equalled at all it is only by atmospheric back-ground. Iconsider it to be the best ever known, and think it needs but to be tried to afford satisfactory proof that it is so.

Although used by few before, since the first edition of this work at least two thirds of the operators have adopted its use;for any one can at once understand the principle and the effect which it produces."It may be added that a motion imparted to to any back-ground where softness is desired, produces an excellent effect.

Gilding Dissolvent.--To one quart of muriatic acid add as much oxide of iron (common iron rust) as it will dissolve in two days.

This may be done by putting in the oxide in excess.

It should be frequently shook, and when wanted for bottling it should be allowed to stand in order to settle. When this is done the solution may be poured off, and reduced by adding to it an equal quantity of water; then it is ready for use.

This constitutes a gilding dissolvent now in our market.

Solution for Removing Specks.--There is probably no one cause of complaint so general as "what makes those black specks?"There are several causes which produce them, and probably the most general are dust, rouge, or a spray of moisture on the plate.

It this be the case, there is no solution which can remove them, as they have prevented a chemical action with the silver, and their removal would only expose the surface of the plate which in itself would afford a contrast with the impression.

Another and less dangerous source of these specks is organic matter contained in the solution employed in dissolving the chemicals, or the water in washing. much of the hyposulphite of soda in market contains a sulphuret, which, coming in contact with the silver surface, immediately causes oxidation.

Such spots, as well also as most all others found on the plate after it has been exposed in the camera, can be removed by the following, solution: To one ounce of water add a piece of cyanide of potassium the size of a pea; filter the solution and apply by pouring it on the surface of the plate.

In all cases the plate should first be wet with water.

Apply a gentle heat, and soon the spots disappear, leaving the impression clear and free from all organic matter.

In the absence of cyanide of potassium, a solution of pure hyposulphite of soda will answer as a fair substitute.

To Redeem, a Solarized Impression.--The Daguerreotype plate, prepared in the ordinary manner, should be exposed in the camera a sufficient time to solarize the impression. Then, before it be exposed to the vapor of mercury, expose it for a very brief period to the vapor of either chlorine, bromine or iodine.

Then expose over mercury, as usual. I have produced singularly interesting results by this process.

To Purify Water.--Filter the water well, and then add about three drops of nitric acid to the pint. This can be used as absolutely pure water, but I would recommend the use of distilled water as preferable.

Cleaning Mercury.--Make a small bag of chamois skin, pour in the mercury, and squeeze it through the leather.

Repeat this several times, and filter by means of a funnel made of paper, with a very small aperture, through which it will escape and leave the particles of dust, or other substances, in the paper.

A paper with a pinhole through it will answer as well, and it is less difficult to make.