It is advisable to treat all three plates in this way simultaneously, so that there may be no delay in the final transfer. For the final support gelatinized paper is required, which has already been dealt with. The paper should be larger than the picture. Having all three images on the waxed papers, the first may be laid down on the dampened final support, lightly squeegeed, and after about half a minute the wax paper may be stripped, and then the other images transferred in the same way. Instead of using the waxed papers, the final support may be squeegeed direct to the plates, and there is even less chance of non-registration.

A cement is not actually necessary, but the final result is stronger if one is used and there is less likelihood of the films separating. Either of those already suggested may be used, but they must not be too freely applied. If the cement is used, it is advisable so to arrange the work that each print may be left for about ten minutes before the next is applied; but the paper must not be allowed to dry, and should be placed face up on a pile of wet blotting or filter papers.

Another alternative is to make two pictures on glass, and the third on thin celluloid, printing through the back to obtain a reversed picture and then cement this down to the other two transferred prints, when the celluloid acts as a protection to the picture. For experienced workers coating the constituent pictures with collodion will naturally suggest itself as a good preventive against expansion, but for the novice, coating with collodion is not such an easy matter, and if this be used more time must be allowed for the stripping fluid to penetrate. If three celluloid films are used, and this is possibly the easiest plan, though there is slight modification of the colors, especially in the more delicate tints, because of the color of the celluloid, then, as we shall have celluloid applied to gelatine, a cement must be used which will act on both, which can be made on the following lines:

Gelatine 2 g.

Pyroxyline 5 g.

Glacial acetic acid 50 ccm.

Methyl alcohol 100 ccm.

Amyl acetate 20 ccm.

Soak the gelatine in the acid and melt by heat, dissolve the pyroxyline in the alcohol and amyl acetate and add to the gelatine solution, stirring well, and, if any gelatine is thrown out, heat a little more.