View Full Version : Tollens' Reagent and Coating

01-23-2009, 01:56 PM
I came across an article about Tollens' Reagent. I noticed that its recipe was pretty close to some of the ingredients in simple silver emulsions. Tollens' was used to coat mirrors a lot. The performance descriptions I've read about it imply that this type of mirroring is fast, smooth and effective. Also, I read one description where the solutions were applied using a small pump sprayer; these coatings were described as being very thin. It seems like Tollens' Reagent would be a great method for getting the emulsion on a base surface.

I found the descriptions of thinness intriguing because some descriptions of emulsions imply that a physically thin emulsion would be faster or more efficient than a thicker, bulkier emulsion. I imagine the truth lies in the proportions.

Since it's used on glass to make mirrors; that seems to imply that it would work really well with smooth surfaces like glass. Maybe it would also work on acetate.

Trouble it, Tollens' Reagent is described as producing elemental silver as its final product. Also, I came across a warning that storing this would produce another compound AGN3, which has explosive properties, as the aqueous Tollens' Reagent would decay.

So, I ask: Has anyone tried Tollens' Reagent as a method for applying the silver compounds to an emulsion? If Tollen's Reagent was used to get the elemental silver onto a film or glass, would there be any way to get the silver photosensitive again?

We know that Silver Nitrate in the presence of Potassium Bromide and Potassium Iodide will create a photosensitive silver halide. But, would elemental silver in the presence of Potassium Bromide also do this?

I have a feeling that it would not. Is that so? Can Tollen's Reagent be used in emulsion making in a way that was effective and efficient? Anyone tried it?

01-23-2009, 02:13 PM
As you may know, a silver-plated and mirror finished brass plate was made light sensitive by exposure to the fumes of iodine (?) (Iodide?) exposed in the camera and then developed with the fumes of mercury to make a daguerrotype. So, indeed silver metal CAN be made light sensitive.

Photo Engineer
01-23-2009, 02:17 PM
And, the problem is that by this method (Daguerre et al) no method could be enhanced for speed or spectral sensitivity except for Silver Halide crystals precipitated in gelatin.

Many efforts were made to speed up the silver mirror light sensitive coatings, albumen and other types of light sensitive systems, all to no avail. So, although it might work, you are stuck with UV sensitive systems with ISO values that are incredibly slow.


01-23-2009, 06:10 PM
Thanks for your quick replies. I'm intrigued by the ideas about emulsions; I enjoy exploring common, low-cost ways to expand my photography skills. Thanks for your valuable input. I've read some posts on here time and again; y'all are very informative. Good luck. J.