an interesting talk on the Lippmann process for colour

Neuhauss self portrait c1901

TorontoI signed in on July 21st, a coolish and sunny night, to hear Dr Hanin Hannouch in Berlin, Germany (2am over there when 8pm the evening before here). The event was sold out on Eventbrite, but our Programme Director opened a YouTube channel in case he had to cut off access. The channel has since been linked to our web site under Social Media in the right hand sidebar. This presentation is our first July talk – usually we go for ten months and take July/August off. 

We began the evening with a brief 30 minute social get together. Once underway, our president, Clint Hryhorijiw introduced the evening covering the society, its ambitions and activities. Among other items, our president mentioned he has lots of photographica to auction; and that the PHSC Trunk Show is ON for this August (15th or 22nd – date to be confirmed).

Celio introduced our speaker, Dr Hanin Hannouch in Berlin and her discussion of the Lippmann interferential colour process as investigated over a century ago by Richard Neuhauss. Hanin has a very young and pleasant voice which she used to speak impeccable English in a very clear and articulate manner. The ZOOM translation software had little difficulty recording the talk although German names and words gave it a fit (Neuhauss came out variously as No House, New House, etc.). Dr Hannouch said copious amounts of coffee helped her stay alert so early in the morning in Berlin.

The use of light in the visible spectrum is the basis for all successful photographic processes. Initially, only the energetic blue rays (and the even higher/shorter rays) activated emulsions.  After years of experimentation, emulsions were made sensitive to mid range visible spectrum rays too (orthochromatic) and finally emulsions were made sensitive even to oranges and reds – panchromatic emulsions. In celebration, most colour processes suddenly displayed red flowers, red dresses, etc to demonstrate their ability to record the full visible spectrum. 

Hanin pointed out that coloured bands on soap bubbles (which almost everyone has seen) are a manifestation of the interferential effect used by Lippmann. We tend to think of photographic discoveries as entirely scientific but she noted that both politics and religion  seem to play a large part too. For example, being Jewish, the Lippmann family suffered persecution in Luxembourg and fled back to France (and obscurity for a time) shortly after Lippmann’s birth. At that time, French and German sciences were competing for supremacy.

In 1908, Lippmann won the coveted Nobel prize  for his work in Physics and was suddenly embraced by his country as a hero. France, through him, had won the Nobel prize in science besting Germany! 

Dr Hannouch Studied the Lippmann process through photographs made by Richard Neuhauss. She noted that these positive photos were often glued to and viewed through a glass plate, or a 10 degree glass prism. The use of a stuffed parrot as the subject helped two fold: The bird was motionless while the minutes-long exposures were taken; and the complex and finicky viewing of the colours created by interference waves could be compared to the original for colour accuracy.

During the Q&A, she noted that Lippmann’s theory was different from the theory that Maxwell set out to prove in 1861. In a well documented experiment, Maxwell photographed a tartan ribbon through three separate filters using three glass plates coated with monochrome (back and white) media. The experiment was intended to prove the three-colour process of human vision as predicted by the Young-Helmholtz theory.

Interestingly, Richard Neuhauss chose a tartan jacket for his 1901 self portrait. A member of our attendees noted that Neuhauss made it with a five minute exposure using the Lippmann process. While the Lippmann process was very slow, so too were the three-colour processes c1900. Dr Hannouch suggested today’s modern three-colour processes benefitted from the intense experimentation that they underwent over the decades while the interferential process languished and all but disappeared, possibly demonstrating the impact of politics over science.  

Her presentation was very well received by an enthusiastic audience with the Q&A session extending a bit longer than Dr Hannouch’s talk itself. An informative and positive evening for all.

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