Dr. Tung H. Jeong
 

Introduction

The GP-2 developing procedure is most suitable for the Russian produced fine grain emulsion now known as PFG-03M  Both the developer and the emulsion are discussed in the book "Silver Halide Materials for Holography and Their Processing" by Dr. Hans Bjelkhagen and published by Springer-Verlag.  The book and the materials are distributed by INTEGRAF (Fax: 847-615-0835; e-mail: tjeong@aol.com).

The ingredients of GP-2 are:

Methylphenidone 0.2 g
Hydroquinone 5.0 g
Sodium Sulfite (anhydrous) 100g
Potassium hydroxide 5.0g
Ammonium thiocyanate 12.0g
Distilled or de-ionized water 1.0 liter
 

Mixing method

Consult a professional chemist or a certified chemistry teacher concerning safety procedure for mixing and using chemicals.  Observe all safety rules at all times.

The contents of each of the five chemicals is dissolved in one liter of distilled or de-ionized water warmed to 50o  - 60o C.  To open each pouch, tap the chemical to the bottom and then cut open the top with a pair of scissors.  Invert the open pouch very close to the top of the water and empty the contents into it.  Avoid contents from escaping into the air.

Keep the mixed solution in a tightly capped bottle and label it  as "GP-2 Developer, Stock".  At room temperature, this solution should be good for one year.

To make a "working solution", mix 15 ml of the stock solution with 400 ml of distilled or de-ionized water.  Label this as "GP-2 Developer, Working Solution".  Keep this at room temperature.
Hologram Exposure

The sensitivity of the PFG-03M emulsion is about 500 mJ/cm2, which is a factor of 5 to 10 lower than Agfa's 8E75 emulsion.  But the PFG-03M has a resolution of 10,000 lines/mm, twice that of the Agfa material, resulting in brighter and clearer holograms.  Since the sensitivity changes based on the history of the emulsion (age, storage conditions, etc.), each batch should be tested for optimum exposure.
 

Developing Procedures

Make and develop holograms in a darkened room illuminated by a minimum of green light.  A green bulb such as those from a Christmas tree decoration can be used underneath the counter or table.  Place obstructions around the light so that after dark adaptation, enough light remain so that the holographer can safely move around.  Make certain that there is no direct light on the holographic plate.

In a tray larger that the hologram, fill with enough working solution of GP-2 so that  the hologram will be fully submerged.  Remember, one liter of stock yield 27 liters of working solution; so don't be stingy.  Develop each hologram with a tray of fresh solution.

1.  Developing:  place the exposed hologram into the solution  with the emulsion facing upwards and do not agitate.  Cover the tray with something opaque and let develop for 12 minutes.

2.  Wash the developed hologram in running water  for at least 5 minutes.  At this time, the room light can be turned on.

3.  (Optional) Soak hologram in a dilute photoflo solution for 30 s.

4.  Lean the glass side of the hologram against a vertical surface, and let it stand on top of a paper towel.  The emulsion side should be expose to air.  Let it dry slowly.  Do not squeegy or use forced air.  It may take over an hour for the hologram to dry.

For transmission holograms, an image can be viewed (with laser light) while the hologram is still wet.  For reflections holograms, no image (using a point source of incandescent light), can be seen until the hologram is thoroughly dried.