A Painless Zap Tester
In the process of getting a handle on the soap making process, I not only re-invented the alkaline battery but also came up with a very simple alternative to the zap test. The zap test is simple enough but has it's own set of issues, i.e sanitation, yuck factor and potential for false negatives. The downside of mine is that it costs $3 if you do not own a voltmeter.
It may be a surprise to learn that the "Energizer Bunny" gets all his energy from a wannabe bar of soap.
An alkaline battery consists of a metal can filled with KOH (sound familiar?) and a metal rod embedded in the KOH. When the metal rod and the metal can are connected to the "Energizer Bunny" he does his thing until the KOH is consumed to point that lets the bunny sleep (no more zap).
If we poke the probes of a Digital Voltmeter ($3 and sometimes free at Harbor Freight) into a bar of soap, we will measure a voltage because the two probes and the soap produce a not very efficient alkaline battery.
The actual voltage measured will depend on two things:
1. The TA (total alkali) remaining in the soap
2. The metal used in the probes
The commercial battery works as well as it does because the metal can has a very large surface area and it is made from a metal that is different from the metal rod.
Using the probes as they come with the meter will work but the value is low enough to make measuring unreliable but still demonstrates the phenomenon which is:
Raw soap (zap level) will read roughly twice the voltage of a safe, non zapping bar.
I have found that among materials readily available, copper and aluminum make very good probes, producing about 1.5V (sound familiar) for a naughty bar and 0.8 or less for a safe bar.
You can use a test lead with alligator clips to experiment with different materials or just wind a short piece of aluminum wire around one tip leaving the end to poke into the soap. The probes are usually plated brass and you can sand off the plating or use as is. Brass is mostly copper. Just to clarify, the probes must be of two different metals to work well.
Using this setup, my pH 12 bar discussed in another thread measures 1.5V and all the rest of my bars are less than 0.8V.
I made a bar using Dunn's oven process and at trace it measured very low presumably because it was still an emulsion and does not conduct very well but within 30 mins it rose to about 1V and slowly rose for the first 3 hours to about 1.4 and then dropped to about 1.0V at 4 hrs and settled at about .6 overnight. Final pH is about 10.5
So there you have my painless zap tester. Not only painless but there will be no false negatives because the probes are actually poked into the soap, below the highly variable surface.
Jack Schmidling, Marengo, Il
In the process of getting a handle on the soap making process, I not only re-invented the alkaline battery but also came up with a very simple alternative to the zap test. The zap test is simple enough but has it's own set of issues, i.e sanitation, yuck factor and potential for false negatives. The downside of mine is that it costs $3 if you do not own a voltmeter.
It may be a surprise to learn that the "Energizer Bunny" gets all his energy from a wannabe bar of soap.
An alkaline battery consists of a metal can filled with KOH (sound familiar?) and a metal rod embedded in the KOH. When the metal rod and the metal can are connected to the "Energizer Bunny" he does his thing until the KOH is consumed to point that lets the bunny sleep (no more zap).
If we poke the probes of a Digital Voltmeter ($3 and sometimes free at Harbor Freight) into a bar of soap, we will measure a voltage because the two probes and the soap produce a not very efficient alkaline battery.
The actual voltage measured will depend on two things:
1. The TA (total alkali) remaining in the soap
2. The metal used in the probes
The commercial battery works as well as it does because the metal can has a very large surface area and it is made from a metal that is different from the metal rod.
Using the probes as they come with the meter will work but the value is low enough to make measuring unreliable but still demonstrates the phenomenon which is:
Raw soap (zap level) will read roughly twice the voltage of a safe, non zapping bar.
I have found that among materials readily available, copper and aluminum make very good probes, producing about 1.5V (sound familiar) for a naughty bar and 0.8 or less for a safe bar.
You can use a test lead with alligator clips to experiment with different materials or just wind a short piece of aluminum wire around one tip leaving the end to poke into the soap. The probes are usually plated brass and you can sand off the plating or use as is. Brass is mostly copper. Just to clarify, the probes must be of two different metals to work well.
Using this setup, my pH 12 bar discussed in another thread measures 1.5V and all the rest of my bars are less than 0.8V.
I made a bar using Dunn's oven process and at trace it measured very low presumably because it was still an emulsion and does not conduct very well but within 30 mins it rose to about 1V and slowly rose for the first 3 hours to about 1.4 and then dropped to about 1.0V at 4 hrs and settled at about .6 overnight. Final pH is about 10.5
So there you have my painless zap tester. Not only painless but there will be no false negatives because the probes are actually poked into the soap, below the highly variable surface.
Jack Schmidling, Marengo, Il
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