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A Biased Guide to:
Water Temperature Control in Photographic Darkrooms

Note: This guide, written by David Hass of Hass Manufacturing Company, is biased. Although everything contained herein is factual, there is a strong preference given to the products made by Hass Manufacturing Company.

Introduction

There are four methods commonly in use in photographic darkrooms for controlling water temperature. There is the ice-cube method, the manual faucet method, the thermostatic mixing valve method, and the Intellifaucet method. Here are brief descriptions of each method, with the pros and cons of each.

1. The ice-cube method (also known as the see-saw method).

Procedure: Set out a beaker on your bench. Fill it with some water a little bit warmer than you need. Put an accurate thermometer in the beaker. Add an ice cube. Read the thermometer. If it doesn't get cold enough with one ice cube, add another. Repeat until it is too cold. Add some more water a little warmer than what you need. Hopefully you'll hit your temperature. If not, repeat the add-ice-cube dance.

Pros: Equipment costs are low (if you already own a freezer). Reliable (I processed hundreds of rolls of film this way and never wrecked a roll). Low-maintenance.

Cons: A pain in the keister. Not useful for rinsing film or paper. Only useful for mixing up developer solutions.

2. The manual faucet method (also known as the 'I hope nobody flushes a toilet' method)

Procedure: If you don't know how to do this, stop reading and send your film out for processing.

Pros: Equipment costs are low. Low-maintenance (unless you have to call a plumber to change your faucet washers, in that case, you'll have to mortgage your house to pay for the service call).

Cons: Unreliable. Risky. Requires constant supervision from the faucet attendant (probably you). Make sure nobody flushes a toilet, turns on the washing machine, turns on the dishwasher, takes a shower, or otherwise uses any water in your house while you are processing film. You could install a shutoff valve to close down all water to the rest of your house while you're processing film, however, this will lead to enormous expenses, such as calling a plumber (see Pros above), and could be dangerous to your person as others in the house stalk you and track you down until you're done developing that really cool roll of T-Max you've been dying to see.

3. The thermostatic mixing valve method (also known as the 'false sense of security method')

Thermostatic mixing valves were a really great advance some 30-40 years ago. They are very simple. Here's how they work.

A bimetallic coil (or fluid-filled coil tube) inserted into a chamber filled with your water expands when the water gets hotter and contracts when the water gets colder (nature uses this method, too ;-) ). The coil is attached to a valve plunger which blocks hot or cold water to keep the temperature swings to a minimum. The thermostatic mixing valve attenuates (reduces) temperature swings, but does not eliminate them.

Procedure: Buy a good quality thermostatic mixing valve (about the same price as an Intellifaucet D250). Install it. Open your sink valve. Rotate the handle of the mixing valve while reading the dial temperature gauge. Wait 2 to 5 minutes. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Read the temperature gauge. Adjust the handle. Wait 2-5 minutes.Read the temperature gauge. Adjust the handle. Wait 2-5 minutes. Ahhh, forget it, just send it out for processing.

Pros: Definitely better than 1 and 2 above. Lowers your blood pressure. Reduces your need to alienate the rest of your family. Simple to operate.

Cons: High-maintenance costs. Rebuilding kits typically run between $150 - $175 and have to be installed once a year for heavy use, less often for lighter use. You know you need a rebuild kit when the procedure above doesn't work any more. Does not "control" the temperature - it just reduces temperature swings. You can't set an exact temperature and then go watch TV while your film is being rinsed. You must check and re-check the temperature to make sure nothing bad happens. If it seems that I've spent more words on these valves than the others it is because thermostatic mixing valves are the main competitors to the Intellifaucet.

4. The Intellifaucet method (also known as the "Awesome" method)

Procedure: Install an Intellifaucet. You can install it right where your faucet is if you like. Very simple. (You might still need to mortgage your house to pay for the plumber, sorry, we ain't perfect.) Rotate the knob on the Intellifaucet to the temperature you want. Wait for the "Ready" light to go on. Done. Finito. At's all folks. The fat lady is singing. You're done!

Pros: It controls the temperature to what you want automatically with no supervision from you. You can't beat that with a stick. Go to the movies. Go watch TV. Read a book. It will be all right.

Cons: None.

September 11, 1998, Version 1.0


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