Collodion

“ The collodion of some makers always acts in the manner you describe; and we have known it remedied by the addition of about one drachm of spirits of wine to the ounce of collodion. Spirits of wine also added to the nitrate bath—two drachms of spirits of wine to six ounces of the aqueous solution—is sometimes very beneficial. When collodion is inert, and the colour remains a pale milk and water blue after the immersion, a few drops of saturated solution of iodide of silver may be added, as it indicates a deficiency of the iodide. ”

“ Collodion in which there is a great excess of ether gives by its evaporation a very tough film; the film left by collodion containing a large quantity of alcohol is soft and easily torn; but in hot climates the presence of an excess of alcohol is an advantage, as it prevents the rapid evaporation of the ether. Under the microscope, the film produced by collodion of good quality appears translucent and colourless. To preserve collodion it should be kept cool and out of the action of the light ”

“ In photography it is used in combination with agents that render it sensitive to the action of light.
Collodion. Syn. Plain collodion. The following are the best methods of preparing plain collodion for surgical purposes:—
Prep. 1. (Ph. U. S.) Nitrate of potassa, in powder, 10 oz.; sulphuric acid, 81⁄2 fl. oz.; triturate together in a wedgwood mortar until uniformly mixed; then add of fine carded cotton (free from impurities) , 1⁄2 oz.; and by means of the pestle or a glass rod, saturate it thoroughly with the liquor for a period of about 3 or 4 minutes ”

“ Collodion Emulsion Processes.—In 1864 W. B. Bolton and B. J. Sayce published the germ of a process which revolutionized photographic manipulations. In the ordinary collodion process a sensitive film is procured by coating a glass plate with collodion containing the iodide and bromide of some soluble salt, and then, when set, immersing it in a solution of silver nitrate in order to form silver iodide and bromide in the film. ”

“ To obtain almost structureless collodion is not an easy matter, and a clever practitioner in this branch of photography states that he knows of no method to accomplish this with certainty, but he himself tries different samples until he falls upon a suitable one, which he then lays aside for this object. A beneficial effect is often derived from keeping the collodion awhile, but this is not always the case. The slides should be chosen of an equal thickness, so that when focussed upon one no re-adjustment may be necessary for the others. ”

“ Collodion Process.—A great impetus was given to photography in 1850, on the introduction of collodion (q.v.) , a very convenient vehicle on account of the facility with which the plates are prepared, and also because it is a substance as a rule totally unaffected by silver nitrate, which is not the case with other organic substances. Thus albumen forms a definite silver compound, as do gelatin, starch and gum. ”

“ On some Points in the Collodion Process.—In your impression of this day's date (Vol. vii., p. 363.) , the Rev. J. L. Sisson desires the opinion of other photographers relative to lifting the plate with the film of collodion up and down several times in the bath of nit. silv. solution; and as my experience on this point is diametrically opposed to his own, I venture to state it with the view of eliciting a discussion.
The evenness of the film is not at all dependent upon this practice; but its sensibility to light appears to be considerably increased. ”

“ The solution, after standing some time, always deposits a small amount of insoluble matter. Therefore, in making collodion solutions, care should be taken to place the containing bottles in a place free from vibration and shock. After standing a few weeks the clear supernatant liquid may be decanted off. On a larger scale collodion solutions are filtered under pressure through layers of tightly packed cotton wool. The state of division is important. When the end in view is the production of a strong film or thread, it is advisable to use unpulped or only slightly pulped nitro-cellulose. ”

“ The discovery of the collodion process by Archer in 1851, quite supplanted the previous method, and gave photography an impetus which has carried it rapidly forward to the present date. Numerous substances have been tried at different times to support mechanically the delicate sun-printed image, but nothing has as yet been found to equal collodion upon glass.
Photographic art has now become such a thing of our every-day life, that perhaps there is scarcely an intelligent person who does not know the difference between a negative and a positive. ”

“ As a good and suitable negative is the foundation of success in the subsequent processes, so is a properly cleaned glass plate the foundation of a successful negative; unless the glass is chemically clean, the collodion film will either be stained or marked, or it will split off in drying, therefore care and attention are requisite; even in preparing a piece of glass for the reception of the film of collodion care is especially requisite, as the want of it cannot be seen until after all the operations, therefore the labor and time are not thrown away. ”

“ It has made modern photography [Pg 118] possible, for the film we use in the camera and moving picture projector consists of a gelatin coating on a pyroxylin backing. If collodion is forced through fine glass tubes instead of through a slit, it comes out a thread instead of a film. If the collodion jet is run into a vat of cold water the ether and alcohol dissolve; if it is run into a chamber of warm air they evaporate. The thread of nitrated cellulose may be rendered less inflammable by taking out the nitrate groups by treatment with ammonium or calcium sulfide. ”

“ Of this paper I take 180 grains to one pint of ether, and having placed them together, I add alcohol drop by drop, till the ether begins to dissolve the paper, which will be denoted by the paper becoming quite transparent. I have rather increased the quantity of paper to be added, as the after treatment rather thins the collodion. This, when shaken up and completely dissolved, forms the collodion. To sensitize I use two preparations, one prepared with potassium, the other with ammonium compounds ”

“ PHOTOGRAPHIC CORRESPONDENCE.
Washing Collodion Pictures—Test for Lens.—As I was indebted to the kindness of Dr. Diamond, amongst other friends, for my original initiation into the mysteries of photography, it may appear somewhat presumptuous in me to differ from one who has had so much more experience in a point of practice. I allude to that of washing the collodion negative after developing, previously to fixing with the hyposulphite of soda; but, probably, the reasons I urge may have some weight. ”

“ The second sample of collodion which you have used is over-iodized. It is quite requisite that it should be known that the sensitive properties of collodion are not increased by adding too much of the iodizing solution. If the collodion is good, the film is semi-transparent, of a bluish opal-like appearance. If the iodine is in excess, it becomes more opaque and creamy after immersion in the bath, and of a deep orange when looked through ”

“ The Troy and apothecaries' ounce are the same, and contain forty grains more than the Avoirdupois ounce. In making collodion, take any quantity of ether, and dissolve the gun cotton in it; if too thick, it may always be reduced by the addition of more ether. Uniodized collodion may be bought quite as cheap as it may be made; and it generally has the advantage of having been made in a large body, and allowed time to settle, whereby the clear portion only is more easily decanted off for sale. ”

“ I have not only tried every purchasable collodion, but my experiments have been innumerable, especially in respect to the ammoniated salts, and I may, I think, safely affirm that all preparations containing ammonia ought to be rejected. Often, certainly, great rapidity of action is obtained; but that collodion which acted so well on one day may, on the following, become comparatively useless, from the change which appears so frequently to take place in the ammoniacal compounds. ”

“ My advice to those who wish to make collodion or gelatine emulsion is, to add the silver to the collodion or gelatine, and then add the haloid salts afterward, and you will get as perfect an emulsion as you choose.
It is a great comfort in the collodio-bromide process that the operator is able to give local intensity (a most desirable quality in all artistic work) to the image. I do not believe any process is perfect until that power is placed in the hands of the manipulator ”

“ With regard to the point, whether the free iodine is the sole cause of the deterioration of old collodion, I should say decidedly not, at least in a theoretical view; the liberation of free iodine necessitates some other changes in the collodion, and the result must be influenced by these in one way or another, but practically I have as yet found nothing to warrant the supposition that they perceptibly interfere with the sensitiveness of the film. ”

“ The layer of collodion is so firmly attached to the coating of the paper that it cannot be injured by contact with a hard object, nor even by slight friction. Besides, the picture can be developed by total immersion in the developing liquid, instead of pouring the latter on the collodion layer, as in the case of plates of glass, an operation that requires some dexterity and long practice. ”

“ Or where I employ collodion, with a view to connect the minute and isolated points of the print firmly together during development, I sometimes ultimately remove the film it forms, by means of a mixture of ether and alcohol, after the picture has been finally mounted, and the support of the film of collodion is no longer required. ”

“ Prepare a similar plate of glass with collodion, and drain off all superfluous nitrate of silver, by standing it for a minute or so on edge upon a piece of blotting-paper. Lay it flat upon a board, collodion side upwards, and the negative prepared above upon it, collodion side downwards. Expose the whole to daylight for a single second, or to gas-light for about a minute, and develope as usual. ”

“ There can be little doubt that the London preparation would be much improved by digesting the flies in the acid for an hour in a close glass vessel at the temperature of boiling water.
f. The cantharidal collodion of M. Ilisch has been considerably used as a vesicant in this country. Ether being a good solvent for cantharidin readily keeps that principle in solution. When applied to the skin, the escape of the ether leaves a coating of ethereal extract of cantharides, admixed with collodion. ”

“ Fox Talbot, as reported in The Times of Saturday last, reminds us of a Query which we have been sometimes asked, and which may just now be brought forward with advantage, namely: If Mr. Talbot's patents extend to the collodion process, how comes it that the earliest practisers of the collodion art had to make their own researches? We know one skilful photographer whose experiments were so extensive before he made any tolerable pictures, that his spoiled glass and cuttings were more than a man could lift. ”

“ It need hardly be said that the plates prepared by some processes are more likely to yield good slides, such as are described above, than plates prepared by other processes; no one process can claim to possess in itself superiority in all respects. Collodion, for instance, is less apt to give foggy slides, and it is easier to intensify than gelatine, but it is also more prone to give "hard" images. Collodion is at its finest in the form of collodio-bromide emulsion, which gives slides remarkable for fineness of grain, for clearness, and for richness of tones ”

“ Originator of the Collodion Process.—All those who take any interest in photography must agree with your correspondent G. C. that M. Le Gray is a talented man, and has done much for photography. G. C. has given a very good translation of M. Le Gray's last published work, p. 89., which work I have: but I must take leave to observe, that it is no contradiction whatever to my statement. The translations to which M. Le Gray alludes, of 1850, appeared in Willat's publication, from which I gave him the credit of having first suggested the use of collodion in photography. ”

“ The filtering is best done by placing a pledget of cotton-wool in the neck of a glass funnel and passing the iodizer through it. To prevent evaporation, lay a glass plate over the funnel.
The iodizer being added to the collodion, shake them up thoroughly and allow to stand for a week to settle, then decant into convenient bottles; this collodion is ready for use in a week, but will improve with age up to six months, after which time it should be mixed with new. ”

“ IMPROVEMENT IN COLLODION.—J. B. HOCKIN & CO., Chemists, 289. Strand, have, by an improved mode of Iodizing, succeeded in producing a Collodion equal, they may say superior, in sensitiveness and density of Negative, to any other hitherto published; without diminishing the keeping properties and appreciation of half tint for which their manufacture has been esteemed.
Apparatus, pure Chemicals, and all the requirements for the practice of Photography. Instruction in the Art.
THE COLLODION AND POSITIVE PAPER PROCESS. By J. B. HOCKIN. Price 1s., per Post, 1s. 2d. ”

“ The colour which iodized collodion assumes on keeping, I consider to be entirely due to the gradual separation of iodine from the iodide of potassium or ammonium originally introduced. There are several ways in which this may take place; if the cotton on paper contain the slightest trace of nitric acid, owing to its not being thoroughly washed (and this is not as easy as is generally supposed) , the liberation of iodine in the collodion is certain to take place a short time after its being made. ”