I see this kind of question very frequently being posted in forums.
I developed my first B&W film. It’s developed ok but I got drying marks on the negative.
I couldn’t find Kodak photo flo or similar product in my city or online. My tap water is hard water. Is that a problem too? Please help.
How does a photographic wetting agent work ? : If you read the contents of a bottle of wetting agent, or their MSDS (material and data safety) sheets, you will find out that photographic wetting agents are nothing but a mixture of very pure detergents and alcohols. The main function of the wetting agent is to reduce the surface tension of water. In simple words this means the ability of water particles to stick together or to other surfaces.
Knowing this, one can use any surfactant (surface tension reducer) as a wetting agent. The only other requirement is that it should not react with the film base, the gelatin, or the silver image.
All of the following can be used as wetting agents:
- Mild shampoo without conditioner (baby shampoos are best).
- Glycerin (1-2 drops per 500ml)
- highly diluted dish-washing liquid. (Make sure it does not have “bleach”, “acid”, etc.)
- In India, there is a seed/fruit called RiTha (रिठा) that’s traditionally used for cleaning Jewelry.
You may be able to think of more. The most important concern is to make sure it’s in very dilute form. If there is too much foam then there is too much wetting agent.
It is also important to dry the film in a proper manner. After rinsing in a wetting agent film should be hung to dry in a dust-free environment and allowed to dry naturally.
Accelerating the process by blowing hot air etc will increase chances of drying marks. In order to create a dust-free environment, you can steam your bathroom (just let the hot water shower run for a bit till the mirror fogs up), or use a water spray (like the ones used by barbers or for cleaning plant leaves) and generously spray the area where you are going to hang the film.
If after carefully doing all this if you are still getting water marks, then you have discovered a new scientific phenomenon that should be thoroughly investigated for commercial possibilities.