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Alternative Photographic Processes - (Hand made photographic -emulsions and processes)

Sizing papers - General information

Different processes may require specific sizing and the information below is only a guide.

With some processes and papers it is necessary to size the paper before the application of the emulsion. This is because paper is made of a mass of finely woven and interlaced fibres and is very absorbent. Without size the emulsion can seep into the fibres of the paper and stain them in a manner where the stain can not be washed out later. Sizing fills the pores or gaps between the fibres keeping the image on the surface and in some cases increases the sensitivity of the emulsion. While some papers have a weak gelatin or hydros animal protein size incorporated in the paper, this may not be enough to prevent the staining and further sizing must be done before the paper can be coated with emulsion.

The most common sizes are colloids, like starch, gelatin and arrowroot. If you are unsure that the paper needs sizing, make a small test print. If the sensitiser immediately soaks into the paper or if the processed image is very faint or looks like it sank under the surface of the paper, sizing is needed.

Sizes

Gelatin size:

7.5mls Gelatin 500ml distilled water 2.5ml formaldehyde Mix the gelatin into warm water to dissolve it. Use this within a short space of time as it will granulate as it cools. It is best to mix fresh size as you need it.

Glucose size:

5ml Glucose 500ml distilled water Mix the glucose into warm water to dissolve it. Use this within a short space of time as it will granulate as it cools. It is best to mix fresh size as you need it.

Starch size:

5ml of liquid starch 500ml water. Starch size keeps better and will not crystallize as it cools. Sizing can be done by either painting on the size solution, or floating it onto the paper in a tray. Different sizes work with different paper and processes and some experimentation may be necessary. For instances gelatin is considered the best for Gum Bichromate printing.

Cornstarch or arrowroot size:

Mix 1 teaspoon of cornstarch or arrowroot with a small amount of cold water to evenly wet it, then add 1 cup boiling water. Spray starch may also be used to size paper. In each case brush the size evenly on paper. Let dry before coating the paper with the emulsion, make sure that the emulsion is on the same side of the paper as where the size has been applied.

Other surfaces besides paper:

Cloth, wood, birch bark, leather, some kinds of plastic, bisque ware ceramics, and other porous, water-immersible materials may also be used.

Size cloth with laundry starch or cornstarch, or spray sizing before coating with sensitiser. Careful laundering of printed garments is recommended.

When coating T-shirts or other clothing, put a sheet of plastic inside the shirt so the sensitising solution does not soak through to the back.

Give very porous objects, such as plaster, a coating of matte spray paint or spray laundry sizing to keep the sensitising solution from soaking in.

Give shiny objects, such as metal or plastic a subbing layer, (thin, fine layer of matte spray paint) to give the sensitising solution something to hang on to. Clean these well before applying the subbing layer. Trichloroethylene is very good.

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