Fog isn't usually a silver bath problem unless the pH is not in the proper range. You might get "comets," clear pinholes, or have a speed/contrast issue, but the silver bath usually doesn't cause problems. You could "sun" the bath if you are not sure. Just put it in a clear glass or plastic open container and set it in the sun away from kids and pets for a few hours. The silver will react with anything organic in the bath and it may turn cloudy and have a black precipitate. Just filter the sunned bath and you should be OK. The ether and alcohol that may have accumulated in the bath will also evaporate during sunning and that will also improve the quality of the silver bath. After some use, you may need to add a little more silver nitrate to keep the strength up. That's all I've ever done and I've been using the same baths for 3-5 years. Others do more like boiling the volume down and neutralizing the bath, but I've never had the need to do so.
But, while we are talking about the silver bath, did you pour a glass plate with salted collodion and let it sit overnight in the silver bath? (Don't use an aluminum plate for this.) You need to do that to obtain proper contrast initially. The silver bath must contain adequate silver iodide (the iodide comes from the collodionized plate) in order to be in equilibrium with the iodide on future plates that are sensitized. If the bath someday gets too much silver iodide in it, you will start to see pinholes on your plates. At that point a more severe maintenance step is required to return the silver bath to the proper state. But don't worry about that now. It may take years before you will have to do something that involved to rescue your silver bath. Directions can be found in some of the early collodion manuals available online if you ever need to remove the excess iodine that builds over time.
Do you know the pH of your silver bath? It should be near neutral (pH 6-7) for negatives and more acidic (pH 4-5) for positives. If the bath is too neutral, you may get some fog. If so, lower the pH incrementally and slowly drop-by-drop with acid until your plates don't show the fogging when everything else (developer strength & time, exposure, etc.) has been adjusted. You only want to add enough acid to get rid of the fog. Too much will lower the sensitivity of the collodion. It is recommended that nitric acid is used for this rather than acetic acid. Acetic acid will react to form silver acetate which may cause later problems and which also takes some silver out of the system. Nitric acid will be in harmony with the silver nitrate but it is also a very hazardous chemical to use. In particular it represents an inhalation hazard that can cause severe corrosion of the lungs with subsequently lethal pulmonary edema. Don't breathe the stuff and keep it off your skin.
Before you change anything else chemically, work on the exposure and development aspect. It sounds as if 2 seconds is too short and 16 seconds is too long. Once you have an image you will be able to adjust other variables one at a time if needed to improve the quality. Don't try to change everything at once.
Based on some exposures done with a Brownie two weeks ago, I would think an exposure of around 4-6 seconds in midday northern skylight on a sunny day would be close to the proper exposure with the camera at its widest aperture. I was in that range with 3-week old collodion and a fresh silver bath. I also used a Brownie that had the aperture removed and a good exposure then was about 1.5 seconds IIRC.
Are you using a book, manual, or some sort of guide as you begin your wetplate trials? The most often recommended are:
- John Coffer's Do'ers Guide to Wetplate Collodion +/- his DVD set. See www.johncoffer.com
- Quinn Jacobson's new manual might be available through http://studioq.com/
- Scully and Osterman's manual or their chapter in John Barnier's Coming Into Focus book on alternative photographic processes. See www.collodion.org
- John Towler's 1864 The Silver Sunbeam
George Berkhofer and Wlll Dunniway also have brief manuals on the process. You can also find other 18th-century references by Desire Monkhoven or Mathew Carey Lea or Estabrooke's book online for free. Googling should turn all of these up.
And I have to push my online article as well. See my signature below for the link.
Last edited by smieglitz; 05-17-2012 at 11:24 PM. Click to view previous post history.
Reason: added safety warning