Maintaining the silver bath for collodion wetplate photography
Part 3: the heavy maintenance to address problems like pinholes, developer distribution and more.
Several problems when photographing with wet collodion plates can be caused by a faulty silver nitrate bath. In the last episodes, I covered those topics and I recommend that you read part 1:
and also part 2:
When do you need a heavy silver bath maintenance
As you know, light silver bath maintenance can be done with sunning and filtering and removes ether and organic substances. It also regulated the acidity of the silver bath because nitric acid is neutralized. This light maintenance is something you can do on a regular basis, if you know how many plates you run through it. Sometimes, some other problems will need a more nasty variation of silver bath maintenance.
Pinholes: pinholes are small black spots all over the plate. Those are present right after fixing and they won’t disappear with washing. This is caused by an over-iodized bath, that means that too many free silver iodides are present in the silver bath and this blocks building up silver iodines in the collodion layer.
Developer distribution: with overworked baths, you will realize that you need to increase the amount of alcohol in your developer to get an easy distribution of the developer when pouring on the developer. The volume of alcohol in your developer should match the volume of alcohol in your silver bath to enable a good distribution. Silver baths with too much alcohol tend to fog your plates, also when measuring the specific gravity, you also measure the amount of alcohol in your silver bath and therefore you get obscured results.
Fogging: if you silver bath fogs your plates, too much alcohol is present so an heavy maintenance should help.
There are plenty of other problems that might be solved by silver nitrate maintenance, just remember: take your time and have a cool head while doing heavy maintenance.
My heavy silver bath maintenance
This is my procedure to reset my silver baths. It is a bit different to other information you may find in the web but it works for me in a very good way.
You will need this equipment to do a heavy maintenance:
a large glass beaker (min. 2l)
distilled Water (a lot)
a big stainless steel pot
a heating plate (best would be induction)
all filtering equipment like described in the latest episodes
a thermometer for higher temperatures (up to 90°C)
Caution: use safety equipment like googles and gloves and keep every a clean and childsafe working environment. Also: do the heavy maintenance outdoors!
Step 1: Precipitation of free iodides
The first step is quite easy, fill in about 1l of your silver bath in a glass beaker and double the volume. In doing so, free iodides will precipitate and turn the silver bath into a milky liquid:
Don’t worry, the bath will be clear as soon as it is heated since the free iodides will break up, this is done in step 2.
Step 2: Evaporating the excess water and alcohol
Alcohol has a boiling point of 78°C, so heating up the silver bath is the only way to remove it. I saw many videos where collodion photographers heat up their silver baths until it boils: don’t do that! Too high temperatures can cause the building up of silver fulminate, that can explode. So keep in mind not to heat up your silver nitrate like water you cook noodles in!
Take your stainless steel pot and fill it with at least 2l of distilled water
Put your glass beaker (that holds the milky silver nitrate) into the pot
Heat up the silver nitrate up to 80°C and check the temperature with a thermometer
Wait until the water has evaporated and the original volume is reached
Step 3: The end phase
After the silver nitrate solution has cooled down, it’s safe to filter it. Do that at least 4-6 times, you will see that a lot of materials are present. After that, check the specific gravity, add silver nitrate crystals or water and note every step you have done in your notebook.
Now you have a nearly brand new silver bath, with no ether and alcohol present, free iodides are gone and it should work like a new bath. Be aware that you won’t need as much alcohol in your developer.
That’s it for now,
Max