When the weather is cool, Collodion plates may be preserved with tolerable certainty for a few hours, by simply applying Honey to them in the state in which they are taken from the Nitrate of Silver Bath.
The best pure Virgin Honey should be obtained by dripping it immediately from the comb. This point is of importance, since if the sample of honey be of inferior quality, or adulterated, the process may not succeed. The quantity of water to be added will vary with the consistence of the honey, from about an equal bulk to two parts: it should be sufficient to make the preservative solution pass slowly through filtering-paper.
After the plate is removed from the Nitrate Bath, it is to be drained and wiped on the back in the usual way. The Honey is then poured along the edge in such a manner as to form a broad wave which forces the Nitrate of Silver solution before it and covers the film. Next drain the plate into a measure and pour on a second portion of Honey as before. This second dose may be used again for the first application to the succeeding plate.
Lastly, stand the glass on blotting-paper in a dark place for about a quarter of an hour or twenty minutes, and wipe the lower edge before putting it into the plate box.
The exposure required will probably be about four or five times as long as that for new and sensitive Collodion, or twice as long as the exposure required for old and brown Collodion.
Before applying the developer, immerse the plate in a Bath of rain-water for five minutes, moving it about occasionally to soften the honey. This will probably be sufficient for plates which have not been kept longer than four hours, and beyond that time the process is not considered certain, since the Honey exercises a slow reducing action upon the Nitrate of Silver.
The solution of Pyrogallic Acid may be used of the ordinary strength, with a full dose of Acetic Acid. Only a faint image comes out at first, but on pouring over the plate a fresh portion of the developer with two or three drops of the Nitrate Bath added to each fluid drachm, it may be intensified to any extent.
Fix with Hyposulphite of Soda, and wash in the usual way.
When the process fails, from heat of the weather or other causes, the image will probably be feeble and red by transmitted light, and the shadows defective and misty. This is especially likely to happen when the Nitrate Bath is very old and contains much Acetate of Silver; or when the same portion of Honey is used more than once, and has undergone partial decomposition by the action of the Nitrate of Silver. The use of pure Honey, free from mouldiness and fermentation, will, in cool weather, almost certainly ensure success.