View Full Version : How Did They Clean Glass For Commercial Plates?

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08-28-2010, 11:40 AM
Hi Ray,
"Perfect"? What is that? The method that I have described on Denise's website "The Light Farm" works for me at least 95% of the time! I started this thread because some pieces of glass stubbornly show beading of distilled water after this cleaning. My original question, which got lost if it was ever addressed at all, was: Can the actual composition of the glass be the cause of this?
I do not use glass only for glass negatives. Glass is the final support for ALL of my art/images. Therefor, I am constantly aware of the color of each piece of glass that I handle. I find that ordinary glass sold at glass cutting stores for picture frames, windows and such, varies wildly in intensity of color.
Moreover, over the past few years, the colors have gotten more varied and more intense.
"Water White" glass is low in iron content but ,these days, expensive !
The glass that I have had difficulty cleaning came from a commercial window glass shop. It is too green to be used as a final support, but probably OK for glass negatives.
Because I have observed that the glass in ALL of the old commercial glass plates from Seeds;Hammer; etc. are close to water white, I wondered if there could be a correlation between elemental contaminants and beading of water. But nobody tackled this question. I assume because nobody knows.

Ray Rogers
08-28-2010, 12:13 PM
Hi Ray,

You were posting while I was writing...
Bill doesn't say so every time (nor should he be required to) but he is working with a non-gelatin synthetic colloid of his own design. His emulsions are gelatin-free, so all the rules are different. He readily acknowledges this. I coated some plates that he had cleaned with his protocol, and they worked great... with maybe a half dozen plates that developed any frilling at all (except when I made the mistake of adding surfactant.) I no longer hesitate to claim authority.

I'm not sure why you won't ever actually make an emulsion, but perhaps you might consider doing so. Experience is always more reliable than 'wisdom'.

Well Denise,
I have to dissagree that the presence or absence of gelatin
does not need to be clearly stated.
While your site does mention Gum, your web site, as well as your own emulsions... are gelatin emulsions, are they not?

Bill's article does state his uses, but I also recall "Using this procedure, I NEVER see frilling or lifting of the emulsion from glass, hardener or none." which I took as a rather strong endoresment of the method for gelatin emulsions. There is a chance I misread Bill, but well, that is why I think it is necessary to state if the procedure has zilch to do with gelatin. Without any such notice, a gelatin or gelatin-polymer mixture is properly assumed.

Now, as far as your next to last sentence, I must say that it is offensive!
You have repeatedly made such comments to me before, and I have resented it each time.
I resent:

1. Your assuming the position of an all seeing God that has the ability
to see what I have done and have not done.

2. Your posting your incorrect assumptions online.

3. Your assuming the role of "authority". IMHO, that is way too premature.

Even at our best, we are all still students.

I don't like your last paragraph... nor my response to it.
We should be friends, not vampires.
If you remove your false claim that I do not make emulsions,
I will remove my related comments.

Ray Rogers
08-28-2010, 12:45 PM
Hi Ray,
"Perfect"? What is that?

Hi Bill.

The perfect comment came from the sentence I quoted to Denise.
I will go get it and past it here:

"Using this procedure, I NEVER see frilling or lifting of the emulsion from glass, hardener or none."

I took this as a rather strong endoresment of the method for gelatin emulsions. There is a chance I misread you.

As far as your real question, let me just say I understood your point.
It was a very deep question, but one for the manufacturer to handle... I imagine there are very few glass emulison specialists today that can speak authoritativly on how various glass compositions affect photographic emulsions and how well they adhere.

I buy my glass directly from the manufacturer.

I thought about commenting on your question, but not knowing the answer, I did not.
I feel the answer is yes but I lack the necessary proof to make such a claim.

As far as glass tint goes... My experience however is different from yours.

You stated that you found today's glass more colored with a greater variety of colors...
is it possible that such glass is comming from China?

Perhaps the more intensely colored glass you are seeing (where ever it comes from) is different from the former glass that was easily found... and you are comparing this newer, more colored stuff to older glass plate glass?

The plate manufacturers probably did select their suppliers,
but I don't have any reason to assume that they used glass as white as what I have bought.

My collection of Eastman glass plates is NOT white glass.
It is the standard green tint stuff. (Isn't the greenest stuff coke bottle glass?!)


sorry - I hesitsted about posting my thoughts because I didn't want to cause trouble... but even here as you will see "never" has decreased to 95%.
When you said "never" I read "100%" ... Slipping to 95% did not escape my notice. That's all I was saying. I belive Kirk and Denise when they say you can clean glass!

I just wish it was still at "NEVER" ! :p

Ian Grant
08-28-2010, 12:49 PM
Back to the OP's question.

Hot water & soap was the norm if glass needed cleaning.

British publicans could tell you that the best way to clean a beer glass was plain soap suspended under a hot water tap followed by a plain hot water rinse. Unfortunately that's banned by the EU, and so machines leave lipstick etc on glasses instead :D

Try washing a glass in washing up liqid, then another in soap powder (used for clothes), the difference is rather surprising :D


Ray Rogers
08-28-2010, 12:55 PM
Baker, writing in the 19-teens, and Wall both address the issues, as does Clerc (1930's) on tropical conditions. Baker goes so far as to list brand names of gelatins and their hardness numbers.[/I].

Yes a lot of people have put in a word or two.
But do you think they are saying:
"You will not experience frilling if you just use a hard emulsion." ?

That is not the way I read their comments at all.
Your earlier comment about needing special treatment ("only if...") seems overstated.

Photo Engineer
08-28-2010, 01:21 PM

There are two hardness numbers.

1. Bloom index or hardness number expressed in a value from about 70 to 300 which relates to the fraction from which the gelatin is made from the initial mix, and relates to chain length and viscosity.

2. Old style gelatin came in 3 levels of allyl thio urea or "hardness" related to its ability to impart sulfur sensitization to an emulsion. Modern photo grade gelatin is inactive and therefore this term is meaningless. Old text books do not differentiate between these two terms very well.

Make sure you know the difference.

The Bloom index is a measure of hardening capability and rate as well as other factors. The longer you keep a glass plate, the harder it becomes (with formalin or chrome alum or glyoxal or whatever). So, a glass plate frills more or less as a function of age as much as anything else. This is covered in both Haist and Mees but just as hardening in general rather than these specifics.


Ray Rogers
08-28-2010, 01:31 PM
Yes. Good point.

There are many instances where one has to make an educated guess at which one is being referred to, but in all fairness, Denise was probably looking in glass cleanng/subbing sections where such confusion is less likely.

BTW, I have found a steady change in the reccomended "hardness" over the early years.

Photo Engineer
08-28-2010, 01:57 PM
Well, in the literature, there was "weak", "middle" and "hard" bloom gelatin referring to Sulfur content, and there was also the same but referring to Bloom Index. It was not until the BI was actually quantified by Bloom that the numbers began to be used, but by then the Sulfur content became irrelevant due to the new refining process for photo grade gelatin.

Early workers used about a 75 BI gelatin but today we generally use a 250 BI gelatin. The 75 hardens very quickly and coats more smoothly (IMHO) than the 250.


08-28-2010, 03:12 PM
When I wrote the article on glass cleaning I was using Both gelatin(from the Formulary) and the modified PVA (one at a time! NOT together) I have described in the "Alternative Process" Forum. My statement that"I never have frilling" was absolutely true at the time! It was also true that the method for cleaning glass which I described in the article ALWAYS produced plates which held standing sheets of water without beading. The fact that the latter is no longer true is the reason I started this Thread. I see now that asking questions that people don't know the answer to only creates friction. Go ahead and use glass upon which distilled water beads up. That is only a test I learned from people who coat thousands of square feet of glass per day. Other than that it means nothing.
I also wish to point out that my emulsions today use different hardeners,dyes and emulsification processes than what I did back then. When I wrote the article on glass cleaning, most of my recipes with gelatin came from people with more experience than I had.
Unless someone comes up with some substantial information, this will be my last post on this topic.

Photo Engineer
08-28-2010, 03:29 PM

I can see your frustration.

Yes, beading is bad and yes a smooth flow of water across the glass is desired. It is important for all vehicles used in coating from gelatin to polymers.

Why this beading changed for you is beyond me. I have no suggestions except that the usual source of this problem is due to oily material in the water used for cleaning, or a change in the "detergent" (read any cleanser into this) used for the cleaning process. At my first workshop at the Formulary, there was a low level oily contaminant in the lab due to other chemicals used there. It caused all sorts of problems. I have found a work around to this problem, but unfortunately it will not work with glass AFAIK.


Kirk Keyes
08-29-2010, 11:38 AM
If you remove your false claim that I do not make emulsions,
I will remove my related comments.

Well, Ray, perhaps it's really up to you to disprove Denise's claim. All it takes is a scan or photo of a plate or neg you've made.

I can personally attest to being a witness of plates made by both Denise and Bill. If you like, I can post a photo of some of my (crappy) plates.

Photo Engineer
08-29-2010, 12:23 PM

I hate to jump into this, but the comment Denise made seems unrelated to the issue and therefore Ray objected to it. I think that we should therefore stay out of it and let them discuss this matter. It is not an issue for me either way.


Kirk Keyes
08-29-2010, 10:50 PM
PE - OK, one second reading, I agree.

Ray - I withdraw my rude post and appologize for making it.

Kirk Keyes
08-29-2010, 11:09 PM
As to the earlier suggestion for using hydrofluoric acid, I'd recommend it not be used by people that do not have the safety training that is really needed for using, or the experience of having already used it.

Hydrofluoric acid has serious complications when it contacts the skin or when vapors are breathed. Hydrofluoric acid is an extremely corrosive liquid and is a contact poison. It readily penetrated flesh and destructively binds with bone.

Additionally, I don't think hydrofluoric acid would help. I think if the glass had something already on the surface that was repelling the gelatin, I suspect it would repell the hydrofluoric acid as well. It would probably dissolve a bit of the glass and make a little bit of releif when compared to the unclean surface of the glass.

That said, I once tested the contents of an abandoned 55 gallon barrel to determine what the contents actually were, and it was 50% sufuric acid and 15% hydrofluoric acid. It was for cleaning windows on commerical buildings. Glad I didn't have a job where I had to use that stuff...

08-29-2010, 11:28 PM
How about the deadly old-school sulphuric acid + dichromate 'lab glass cleaner'? It is a nasty mixture to work with, but it sure does clean!

Ray Rogers
08-30-2010, 12:29 AM
Thank you Kirk.
Apology accepted.

(Thanks also to Ron, for his post which resulted in Kirk taking a second look).

It appears Hydrofluoric acid may have found use cleaning glass
for some autochrome plates as well....

Given a desire to use chemistry rather than "elbow grease",
I think I would prefer ‘Carey-Lea’.

(The cleaner mentioned by Hexavalent).


Kirk Keyes
08-30-2010, 12:36 PM
How about the deadly old-school sulphuric acid + dichromate 'lab glass cleaner'? It is a nasty mixture to work with, but it sure does clean!

That's certainly an excellent glass cleaner - not fast though as you typically place the glass into the dichomate/sufuric solution (aka Chromic Acid cleaner) and let it sit for a while.

Note I suggested the use of NoChromix as a replacement for chromic acid cleaning baths. It's works pretty much as well as chromic acid solution and without the environmentally hazardous hexavalent chrome.

Photo Engineer
08-30-2010, 01:51 PM
Chromix gives no details in their MSDS citing it as a proprietary mixture.

Wonder what it is?


Kirk Keyes
09-01-2010, 12:08 AM
Chromix gives no details in their MSDS citing it as a proprietary mixture.

Wonder what it is?



If I remember correctly, it's an oxidizing organic compound. I seem to remember that it does generate some bubbles when mixed up.