How Did They Clean Glass For Commercial Plates?

[Kirk Keyes]

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]

Kirk;

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.

PE

[Kirk Keyes]

PE - OK, one second reading, I agree.

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

[Kirk Keyes]

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...

[Hexavalent]

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]

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).

Ray

[Kirk Keyes]

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]

Chromix gives no details in their MSDS citing it as a proprietary mixture.

Wonder what it is?

PE

[Kirk Keyes]

Chromix gives no details in their MSDS citing it as a proprietary mixture.

Wonder what it is?

PE

"NoChromix"

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