A convenient way of doing this is to have two bottles, and a large funnel with a sponge pressed into the neck of it; or, what is better, some filtering paper folded in it.
The solution in one bottle, the funnel is placed in the other, and the picture held over it; when the solution is poured on the plate, it runs from it into the filter, and is always ready for use.
It is best that the washing be done immediately on the plate coming from the mercury bath.

If allowed to stand long with the coating on, it assumes a very dark tint--as the operation of the light continues, though less active than while exposed in the camera, and destroys that brightness which would otherwise have been obtained.

It is preferable to wash and gild a picture without it first being dried; yet when there are doubts of its giving satisfaction, there would sometimes be a saving by drying and getting the decision of the subject before gilding, as this last injures the plate for another impression.

First, light your spirit-lamp, then with your plyers take the plate by the lower right-hand corner, holding it in such a manner that the plyers will form in a line with the upper left-hand corner; pour on, slowly, the hyposulphite solution, slightly agitating the plate, until all the coating is dissolved off; then rinse off with clean water, and if it is not to be gilded, dry by holding the plate perpendicular with the bottom left-hand corner lowest, and applying the blaze of the spirit-lamp to the back, at the same time blowing gently downward on the face of the plate.
The hyposulphite solution should be often filtered through a sponge, and it will answer for a great number of washings.

Yet it is observed that the mercury collects in this solution in small globules; these often come in contact with the plate, causing white spots, which spoil the impression.