This section is from the American Hand Book of the Daguerreotype, by Samuel D. Humphrey. Published S. D. Humphrey, 37 Lispenard Street 1858.
In consideration of the importance of galvanized plates, I shall endeavor to give as plain and concise a manner of manipulation as possible. For some time it was a question among the operators generally, as to the beneficial result of electrotyping, the Daguerreotype plate, but for a few years past our first operators have found it a fact, that a well electro-silvered surface is the best for producing a portrait by the Daguerreotype.
From my own experiments, I have found that a plate, by being galvanized, can be rendered more sensitive to the operation of the light in proportion of one to five, viz.: if a plate as furnished by the market, be cleaned, polished, coated and exposed in the camera, if the required time to freely develop an impression be ten seconds, a similar plate prepared in like manner and galvanized, will produce an equally well-defined image in eight seconds. In connection with this subject, there is one fact worthy of notice; a plate with a very heavy coating of pure silver, will not produce an equally developed image, as a plate with a thinner coating, hence the thin coating, providing it entirely covers the surface, is the best, and is the one most to be desired. The experiment is plain and simple. Let the slate receive a heavy or thick coating by the electrotype, then polish, coat, expose in the usual manner, and the result will be a flat, ashy, indistinct impression; when, on the other hand, the thin coating will produce a bright, clear and distinct image, with all the details delineated.
The style of battery best for the purpose has been, and now is, a question of dispute among operators; some preferring the Daniell battery to Smee's. Some claim the superiority of the first from its uniformity of action; others, of the latter, for its strength. I consider either good, and for the inexperienced would prefer the Daniell. This is more simple in its construction, while it has certainty in action. The more skillful electrotyper would prefer Smee's, and this is the one most generally in use. I would remark that the plan of galvanizing plates should be followed by every operator, and when once thoroughly tested, no one will abandon it.