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Bromide Paper: Gelatino-Bromide Emulsion Coated on Paper
Charlie

Created by

Charlie

18. October 2026DE
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Bromide Paper: Gelatino-Bromide Emulsion Coated on Paper

Bromide paper is paper coated with silver bromide in gelatin, the printing and enlarging paper of the darkroom. Thorpe (1913) gives a beginner's emulsion: gelatin swelled in potassium bromide solution, silver nitrate made clear with strong ammonia, the two joined under ruby light, ripened, set, washed, and spread on paper as on a glass plate. From the moment the silver goes in, work only by ruby light. Grain and ounce figures are Thorpe's; the gram conversions and the 10-sheet batch are ours. The picture: our own drawing.
Advanced
4 days

Instructions

1

Swell the gelatin

Dissolve 185 grains (12.0 g) of potassium bromide in 5 oz (142 ml) of water. Cover 300 grains (19.4 g) of hard gelatin with it and stir until it softens and swells.

Materials for this step:

Potassium BromidePotassium Bromide12 g
Gelatin PowderGelatin Powder19.4 g

Tools needed:

WaterWater
Glass BeakerGlass Beaker
Glass Stirring RodGlass Stirring Rod
Balance ScaleBalance Scale
2

Dissolve the silver

Dissolve 231 grains (15.0 g) of silver nitrate in 5 oz (142 ml) of water with gentle heat in the water bath. Add strong ammonia (0.880) a little at a time, stirring, until the precipitate that first forms dissolves again.

Materials for this step:

Silver NitrateSilver Nitrate15 g

Tools needed:

WaterWater
Strong Ammonia Solution (0.880)Strong Ammonia Solution (0.880)
Glass BeakerGlass Beaker
Glass Stirring RodGlass Stirring Rod
Large Pot (lower, for water bath)Large Pot (lower, for water bath)
3

Melt the gelatin, never above 35 °C

Stand both vessels in the pan of water, never above 35 °C, stirring, until the gelatin is perfectly liquid. Up to here ordinary light is fine.

Tools needed:

Large Pot (lower, for water bath)Large Pot (lower, for water bath)
ThermometerThermometer
Glass Stirring RodGlass Stirring Rod
4

Add the silver under ruby light

From now on, ruby light only. Pour the silver solution into the gelatin in a thin stream, stirring all the time. Rinse the silver beaker with about 1 oz (28 ml) of warm water into the emulsion.

Tools needed:

Ruby SafelightRuby Safelight
Glass BeakerGlass Beaker
Glass Stirring RodGlass Stirring Rod
WaterWater
5

Ripen

Leave the emulsion in the hot water for half to three-quarters of an hour.

Tools needed:

Large Pot (lower, for water bath)Large Pot (lower, for water bath)
Ruby SafelightRuby Safelight
6

Set in the dark

Pour it into a flat dish, put it in a light-tight box and let it set for at least 24 hours; two or three days is better.

Tools needed:

Shallow Ceramic TraysShallow Ceramic Trays
Light-Tight BoxLight-Tight Box
7

Wash through canvas

Scrape the set jelly onto wet coarse canvas and tie it into a bag. Knead it under water so it squeezes through in threads. Pour off the water, cover with fresh, wait 5 minutes and pour off: six to eight times.

Tools needed:

SpatulaSpatula
Canvas FabricCanvas Fabric
StringString
WaterWater
Ruby SafelightRuby Safelight
8

Drain and store

Turn the threads onto a strainer covered with a cloth and let the water drain. Rinse with methylated spirit and keep in a lidded jar until coating.

Tools needed:

StrainerStrainer
Muslin ClothMuslin Cloth
Denatured AlcoholDenatured Alcohol
Glass Jars with LidsGlass Jars with Lids
Ruby SafelightRuby Safelight
9

Coat the paper

Melt the emulsion in the warm water bath. Lay a sheet of paper flat on a levelled glass slab. Pour emulsion on the middle to cover nearly half the sheet, and spread it to each end with a glass rod 2 inches wider than the sheet, held just off the surface.

Materials for this step:

PaperPaper10 sheets

Tools needed:

Large Pot (lower, for water bath)Large Pot (lower, for water bath)
Glass SheetGlass Sheet
Spirit LevelSpirit Level
Glass Stirring RodGlass Stirring Rod
Ruby SafelightRuby Safelight
10

Dry

When the coat has set, move the sheets to a rack in a drying box with a current of air. They dry in 12 to 48 hours. Keep them in the light-tight box.

Tools needed:

Drying RackDrying Rack
Light-Tight BoxLight-Tight Box

Materials

4

Tools Required

20

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Bromide Paper

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