CHAPTER VII.
Negatives Suitable for Collotype.
A COLLOTYPE plate may be readily produced from any negative, but the highest results are naturally only obtained when the negative is prepared with a view to its special use. First should be considered the question—May the negative, without detriment to the finished print, be utilised without a reversal? In the not very frequent case of this important point being immaterial, it is simply necessary to produce the negative on patent plate, and it is at once available for printing from. As the negative may easily sustain damage in any of the various operations, it should be thinly and evenly varnished; this, while affording protection, does not mar the sharpness of the resulting print to any appreciable extent.
Reversed Negatives.—In the majority of cases, the resulting copy has to exactly correspond with the original as regards the position left and right, and in such cases the negatives will have to be reversed. This is usually effected in one of four different ways—
1. Reversal of the image by reflection with a prism or mirror, or reversing the plate.
2. Stripping the negative from the glass.
3. By the dusting on or powder process.
4. By the use of negative films.