Use of Talc in Ag Emulsions

[wildbillbugman]

For P.E. and All,
Talc is used as a Lubricant; a Thermal; and mechanical energy absorbent. Is it used in Ag-gelatin emulsions?
Bill:munch:

 

[wildbillbugman]

I guess that no response to this question indicates that no one has tried it or, more likely, everyone thinks it is a stupid idea. Well my initial results show a ROCK HARD emulsion that exposes and develops well. More later.

 

[juan]

Keep us posted.
Juan

 

[pschwart]

I guess that no response to this question indicates that no one has tried it or, more likely, everyone thinks it is a stupid idea. Well my initial results show a ROCK HARD emulsion that exposes and develops well. More later.

Not stupid, just never used it beyond trying to knock down gloss in some alt process prints. Some talc sources include additives. What did you use?

 

[wildbillbugman]

pschwart,
The talc I use is clean. No additives. When I was working in U.V. Curable coatings that needed to withstand high temperature
"shock", talc absorbed much of the mechanical stress from thermal shock. In these cases, talc was usually 10-20%. I really don not know why I have not tried this earlier.

 

[Photo Engineer]

Talc is not used, but other metal oxides are such as TiO2 or other insoluble metal salts such as Baryta.

PE

 

[wildbillbugman]

Thanks PE,
In Our Thermal shock coatings Baryta was also used. But it was not as effective as talc for stress absorption. I intend to look at it. I will be releasing a non-gelatin panchro emulsion soon, barring an unforeseen problem.
The talc has done wonders for wet coating as well as resistance to strong developers like D-19. Also talc helps with staining of the emulsion surface during processing.

 

[wildbillbugman]

I am drying a study of talc levels in a silver-halide emulsion. I should be ready to report by next Tuesday.
Bill

 

[wildbillbugman]

Hello All,
I have now tried enough emulsion using pure talc to make a statement that , in a PVA based emulsion,talc gives me beautiful results. I have an emulsion that exposes well at 1 to 10 seconds in camera at f4.7. After developing, in home made D19 the emulsion not only holds up perfectly but is rock hard when dry. I have been told that gelatin plus talc equals a big sticky mess.
Bill

 

[Photo Engineer]

That didn't come from me. You can mix powdered forms of many metal salts with gelatin with no bad reaction, but it is often pH dependent.

PE

 

[wildbillbugman]

Sorry PE,
No. You are not the person who told me that talc in gelatin is a mess. You did say that "talc is not used". I assume in gelatin emulsions.
I have not used gelatin ,accept to eat it, in years.

 

[pschwart]

Hello All,
I have now tried enough emulsion using pure talc to make a statement that , in a PVA based emulsion,talc gives me beautiful results. I have an emulsion that exposes well at 1 to 10 seconds in camera at f4.7. After developing, in home made D19 the emulsion not only holds up perfectly but is rock hard when dry. I have been told that gelatin plus talc equals a big sticky mess.
Bill

I have been told that gelatin plus talc equals a big sticky mess.
I have made carbon tissue that had talc added to the gelatin for a matte finish and not had a problem.

 

[wildbillbugman]

OK- That was just something I was told. I have not worked with gelatin for years, literaly