A Note on the Author

The below text was written by the Mr. Berkhofer many years ago. Long before he would go on to write his Collodion Manual. In the years after writing this passage he unfortunately grew weaker and due to a heart condition was unable to make as many plates as he would have liked. However his passion never faded even as his body did. He continued to experiment and tinker up to his final days finding the perfect toning, or best subject he could. What we have here is a great little beginning insight into how he got his start, and his approach to this art. In his own words.

The Perfect Formula

When my friend John Hurlock and I began to make wet plates we had no formulae. We were in the Oak Lawn, Illinois high school, he a junior and I a sophomore. It was in early March, 1955. For over a year we had been making gelatin dry plates and had become relatively successful, with exposures as little as 1/100 sec. at F/8. From this experience we knew there would have to be iodide and bromide in collodion, but of proportions we knew nothing. Encyclopedia articles helped little, merely speaking of "iodized collodion." And so we cheerfully bought "flexible" collodion and added a few crystals of both potassium iodide and potassium bromide plus a little alcohol to thin the mixture. As for developer, again we had only the non-specific encyclopedia articles mentioning iron sulphate; for fixer, potassium cyanide. Somehow on March 27th I managed to obtain a plate with part of it having a recognizable image; John got his a day or two later.

Later in the spring, John obtained a copy of the Photo Lab Index, which at least gave developer and fixer formulae, and we had determined that we needed to use "plain" collodion, not the "flexible" variety with its addition of castor oil. From this point onward we began our search for the perfect collodion formula. John has now worked for the NALCO Chemical Company for over 35 years as a polymer chemist, but even then he was highly knowledgeable and took the lead in our research.
As many a wet plate photographer knows, a collodion composed of just potassium iodide and bromide has a relatively slow speed, no matter how little the amount of acid in the silver bath. So, our hunt for accelerating chemicals began. By the end of the summer of 1955 we were regularly adding ammonium iodide to the colloion, with a resulting considerable increase in speed. Our developer and fixer solutions remained the same:

Ferrous Sulphate 30 grams
Glacial Acetic Acid 30 c.c.
Water 500 c.c.

Sodium Cyanide 30 grams
Water 500 c.c.

A collodion containing ammonium iodide, of course, tends to deteriorate quite quickly, so a stabilizing factor was needed. In addition, the slight degree of solubility of potassium bromide in collodion suggested that another bromide be substituted for it. By the winter of 1955-56 we were regularly adding cadmium bromide to our mixtures. Its extreme solubility in collodion plus its tendency to slow the deterioration of ammonium iodide soon convinced us of the necessity of its inclusion.

In the spring of 1956 my family sold our home in Oak Lawn, and we eventually resettled in Wayne, Michigan, outside Detroit, where my father had secured a new job.
Thus, the close working relationship John and I had enjoyed for several years came to an end. However, we exchanged letters on virtually a weekly basis, sharing our latest discoveries and successes. At that time I was still using a turn of the century 4x5 dry plate camera, but he had already switched to a 6 ½ x 8 ½.
 John entered Northwestern University that fall and I entered my senior year in high school, graduating the following June.

During the following several years there were really only two improvements we made in our operations. John discovered that the life span of a wet plate could be lengthened if it were dipped in a magnesium nitrate solution before leaving the darkroom and then redipped in silver nitrate before exposure. Magnesium nitrate is highly hygroscopic and keeps the plate moist. We both also began to eliminate potassium iodide completely from our collodion and substitute cadmium iodide, as that, too, helped stabilize ammonium iodide. Thus, our collodions now were composed of two cadmium salts and two ammonium. Now that the colldion was satisfactory we would truly begin the search for the perfect formula. The "Philosopher's Stone" had to be out there somewhere!

I entered the University of Michigan at Ann Arbor in the fall of 1957 and whole new worlds opened. One I particularly relished was the EngineeringLibrary. Here was housed a wonderful collection of original manuals on daguerreotypes and wet collodion.

Being the '50's, no one had any interest in these and I could check out what I wanted. And so I copied, copied and copied formulae, waiting for holidays and summer vacation when I could try them.

My family was fortunate in that my father obtained a new job back in Chicago in August 1958, so we returned to Oak Lawn. Of course I would not graduate until 1961, but John and I could collaborate again at certain times of the year. Now our experiments consisted mostly of varying the quantities of the salts on a grain-by-grain basis. Occasionally we would try something new, such as the addition of sodium iodide or lithium bromide to the collodion. At other times months would go by with no experimentation, just pleasant picture taking. While in Wayne, Michigan I had obtained an 1880's American Optical Co. camera, which I still use. John continued to use his 6 ½ x 8 ½ dry plate camera, too. I had also located a copy of N. G. Burgess' 1862 "The Photograph Manual," which cost me all of $8.50, but I never really cared for his formulae.

Following graduation in 1961, I worked for a year at a hospital to raise funds to go to graduate school. I am still using up the supply of gum sandarac and sodium cyanide I laid by at that time. I enrolled at the Univ. of Illinois in 1962 and would study classical philology there on the Urbana-Champaign campus until 1966. During that time one of my happiest discoveries was to come into contact with Louis Walton Sipley of the American Museum of Photography in Philadelphia. Through him I was able to obtain original copies of several books, including, "The Silver Sunbeam" by Towler, "A Manual of Photography" by Carey Lea and some random issues of the " Philadelphia Photographer" from 1865, 66 and 68.

The "Philadelphia Photographer" I treasure still for its tipped-in plates. I had already devoured the U of I's collection of them and "The Photographic Times." The manual by Lea proved a godsend. Its formulae were excellent and the procedures highly workable. To this day I still consult it. All through the mid '60's I continued to experiment now and then, but once I found several of Lea's formulae that gave outstanding results, I always came back to them. It was also at this time that I first began to prepare my own albumen paper. However, there was no pressing need for it as the Kodak Studio Proof was still available, as was a similar product by ANSCO. Toning either with gold chloride gave the same tonal values. My only other change in procedure was to abandon using an albumen substratum on the glass and depend solely on roughened edges and corners to bind the collodion to the glass plate.

Leaving the University of Illinois in 1966, I took my first job in Springfield, Ohio and lived in an apartment until a year after my marriage in 1969. Regrettably there was no room for a darkroom until after my wife and I bought our home in 1970. And so, for four years I did wet plates only when I visited with my parents. Since the creation of my own darkroom again, I have continued to use wet collodion, but I think the days of seeking the perfect formula are now past. They are past simply because there is NO perfect formula! After forty-four years of experience, I have come to the simple conclusion that what is perfection for one person is a seriously flawed formula for another.
If, then, I am no longer experimenting, what are my choices of formulae?


I prefer Lea's Landscape Collodion #7 for every purpose, but others prefer to use mixtures which include potassium iodide and a little water to effect the solution of any potassium bromide formed as a byproduct. The only salts I never tried were zinc iodide and lithium iodide (I never could find either), sodium bromide (seemed to be little advantage over the potassium), or ferrous iodide which you have to make yourself and Burgess says is very short-lived. Occasionally I will check my old notes and mix up a formula I tried years ago, but I always find the Lea formula superior. Like all collodionists, I have a bottle in which I keep the remains of failed experiments and old, out-of-date reddened collodion. And sometimes very superior results can be had by using this, or mixing it with new collodion.


I keep on hand a bottle each of Lea's Weaker and Stronger iron developers with full acetic acid content and sugar. Yet others prefer pyrogallic acid, which I have not used since 1958, disliking the length of development time and the possibility of detaching the collodion film from the glass. Some people say that they cannot get enough density with an iron developer and must then redevelop. I have always found that, if the exposure is appropriate to the light, an iron developer gives a perfectly dense, printable negative. I use the stronger for exposures of 5 seconds or less, and the weaker for those exceeding 5 seconds.


Yes, I still use cyanide, in the same proportions as I did in 1955: 30 grams to 500 c.c. of water. Some people cannot stand to be near cyanide as it makes them physically ill. My friend John has always been that way. I guess I am lucky because it has never affected me and I never use rubber gloves. Without gloves it is also easy to remove silver stains while you are manipulating the plate. However, I would not recommend the procedure for everyone!


Now that the Kodak and ANSCO p.o.p. Studio Proof is gone; I regularly make my own albumen paper. I prefer to make it using one of Towler's formulae for plain salted paper, which includes ammonium chloride, sodium chloride and sodium citrate. I suppose it's "cheating" to use this with albumen, but it certainly gives a rich purple image if properly toned with gold.

Yes, I guess my days of gradually altering formulae grain by grain to see whether there was a magical effect are definitely over. Yet, if the romance of experimentation is gone, it has been replaced by the solid pleasure of using something fairly reliable. I still take wet plates because I love the miracle of creating the image from the basic chemicals with my own hands. I love the 19th century optics of my old lenses and the beauty of an antique, wooden camera. My pictures owe nothing to any commercial manufacturer of film, cameras or "photographic" chemicals. The occasional failure only whets the appetite for more exposures. Then, too, I suspect I am an escapist who has always wanted to slip back into the 1860's. If only I could be on hand when Mr. Lincoln comes to the studio for his next sitting!

After forty-four years of making wet plates my only regrets are, one, the hideously rising prices and narrow availability of chemicals; two, the thought that at age 60 my hands may go one of these days and I will no longer be able to pour the plates, and three, since I still work six or seven days a week, my lack of time to devote to this wonderful art.