The chemical reactions that occur during film development are designed around specific temperatures. Some developing processes are more temperature-sensitive than others, and require precise control during processing. Placing your bottles of chemistry and your developing tank in a water bath is one of the best and most accurate ways of controlling, and more importantly maintaining, the temperature of your chemistry. Combining a sturdy container with our TCS-1000 Temperature Control System allows a large volume of water to be raised to the correct processing temperature for developing your film. Here are some general best practices that will help you achieve the best results with your CineStill chemistry.
When it comes to a water bath, bigger is usually better. A larger volume of heated water will be better able to transmit heat into your bottles and developing tank than a smaller volume of water. We like to use a 16 quart plastic tub here at CineStill. The material your water bath is made of also matters. Choose an insulating material like plastic, as a conductive material like metal will lose more heat into the air, cooling down the water. Be mindful of the surface your water bath is sitting on as well. A warm tank of water will lose quite a bit of heat if it's sitting on a cold stone countertop. A folded towel placed underneath the water bath can help insulate it from a cold, conductive surface.
Measuring the Temperature of Your Chemistry:
If you're using the TCS-1000 in a water bath configuration, it's important to measure the temperature of the chemistry directly by placing a thermometer into the chemical storage bottle itself. The TCS-1000 is designed to circulate liquid and bring it up to a target temperature, measuring the actual temperature of the liquid flowing over its internal sensors. However, in a water bath setup, it doesn't know the temperature of the chemistry inside your chemical storage bottles. So don't assume that the chemistry is up to temp the minute the TCS-1000 beeps and shows that the water has reached the target temperature.
Check the thermometer that should be sitting inside of your bottle of chemistry. If the temperature is lower than the target, wait a bit longer. It takes time for the thermal energy generated by the TCS-1000 to transfer from the unit to the water, then from the water to the chemistry sitting inside of the bottle. Depending on how much heat is being lost from the whole system (through conduction to the surface the bath is sitting on and radiation into the surrounding air), it may be necessary to raise the target temperature slightly in order to achieve the correct processing temperature in the bottle.
Keeping your Developing Tank in the Bath:
During your developing process, keeping your developing tank inside of the water bath while you're not doing inversions is a great way to ensure that the tank spends as much time as possible in a temperature-controlled environment. This is important because the tank will be losing heat to the surrounding air while being inverted outside of the bath. It will lose more heat the lower the volume of solution in the tank and the lower the ambient air temperature.
For a long, particularly temperature-sensitive process like developing slide film with the D9 "DynamicChrome" 1st developer (9 minutes at 1:1 dilution, 10.5 minutes at 1:2), placing the developing tank into the water bath in between inversions is a very good way to maintain your temperature to ensure proper density and color.
*If you are not using a water bath, increasing the temperature of the chemistry by a few degrees is recommended to offset the temperature loss happening during the processing time.
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