Making Colloidal Silver with modern technology has never been easier but you still need to follow certain rules to achieve a top quality solution.

You will often hear people say ‘I make perfect Colloidal silver with just a battery and a couple of wires’

They are certainly making a solution containing some colloidal silver but it is far from perfect.

The best way to understand the reason for the various technologies used is to look at the history of low voltage home colloidal silver manufacture.

1) Single Battery Generators.
The earliest units consisted of a PP3 battery with two crocodile clips and two short lengths of silver wire. This produced 9v at the electrodes which although is enough to generate some silver ions, is very slow to get started as the distilled water is a very poor conductor. For this reason, most people moved on to the next type of unit which had multiple batteries.

2) Multi Battery Generators.
By using three batteries in series we now have 3 x 9v or 27v at the electrodes. This allows a larger current to flow in the pure distilled water so the ions are produced much faster but causes another problem. As the ion concentration increases, so does the current. This creates a positive feedback loop which causes the current to increase exponentially. As we now have 27v at the electrodes, quite high currents will flow after a while and the solution will often turn grey with the large amount of silver hydroxide/silver oxide produced. Although these are not toxic, they spoil the appearance of the solution and are not what we are after which is the silver ions and silver particles. They gained the nick name of ‘Mud Makers’ for the murky solution produced. For this reason most people moved on to the next type of generator.

3) Multi Battery with Resistor Current limiting.
There are various ways to limit the current. The first and cheapest way is with a resistor. The limits the maximum current but also limits the current throughout the process so will slow the process down significantly as the voltage drops. For this reason most people moved on to the next type of generator.

4) Multi Battery with Voltage Regulator Current limiting.
By using an integrated circuit as the current limiter, the voltage will stay at 27v until the current limit is reached. This is typically 2-3 times more time efficient than the resistor method and is the start point for most modern generators produced today.

For people making large batches or small batches regularly, the battery cost becomes an important factor so mains powered units have become the normal for all but the entry level units.

5) Mains Powered Current Limited.
There are two ways of producing the 27v or higher voltage required for the electrolysis process. The first is to use a 27v transformer but these are not a common item so add unnecessary costs. The second is to use a DC to DC converter that takes a standard 5V USB power supply and multiplies it up to 27v or greater. This is the approach taken by almost all modern generators.

If 27v works better than 9v why not use 100v?
There is a trade off between speed of production and safety. It is generally recognised that 40v is a safe cut off point above which there exists a shock hazard although 40v is erring very much on the safe side. Most units available today are 40v or less for this reason.

6) Mains Powered with Variable Current Limiting.
The solution produced is highly dependant on the current used to produce it. Very low currents (<1mA) will produce almost pure ionic silver with virtually no colloids. Higher currents (above 5mA) will produce a blend of ionic and colloidal. Very high currents (>10mA) will produce a blend but much quicker and with larger particle sizes. Larger electrodes will require a proportionately higher current to achieve the same results. For these reasons, variable current is required for all but entry level units.

Stirring the Solution.
Now that we have our generator producing the correct voltage and current, we still have a couple of problems to solve. As the electrolysis progresses, there will be a build up of silver hydroxide on the electrodes. This will grow like a furry jacket between the electrodes until it reaches the other electrode. You can either stop the process and lift the electrodes from the water and wipe with a kitchen towel (this will need to be done several times for strong solutions) or you can stir the solution to prevent this build up.

Mechanical Stirring.
There are several ways of mixing the solution prevent buildup and the first one used was the mechanical stirring method. This is achieved using either a laboratory grade PTFE mixing bar with magnets rotating underneath, or by an overhead motor and stirring propeller. Both will work fine but as overhead PTFE propeller bars are expensive, most manufacturers will use plastic propeller mouldings typically used for model boats (black plastic instead of white). You want to keep as little plastic as possible in contact with the solution and only food grade plastics should be used. We use the PTFE mixing bars in our Compact 3 unit.

Bubble Stirring.
Bubble stirring works by using an aerating pump from an aquarium to cause a flow of bubbles past the electrodes causing a circulation away from the electrodes. This method works fine but is not recommended as it introduces dust from the air into the solution and also will cause CO2 to be dissolved into the solution which will make all of the solutions slightly yellow. (Pure ionic solution will be water clear)

Electronic Stirring.
Electronic Stirring works on the principle of ionic flow. When power is applied to the electrodes, one electrode will begin to deposit silver hydroxide and silver metal as a furry coating, the other will release silver ions into the solution. The ions all flow in one direction. If we now reverse the power to the electrodes, any furry buildup will be returned back into solution and the ion flow will reverse. There is no visible motion in the solution but the effect is the same as with mechanical stirring and no plastic stirrer is required to be added into the water. This adds significant costs as the unit now requires a microprocessor and other circuitry to control the polarity switching but is extremely effective.

Almost there!
Now we have our correct current and our nicely stirred solution, we need to know when the process is finished. The early units measured the conductance of the solution to decide if the strength was correct. The problem with this approach is that the conductance is highly temperature dependent and non linear so will need to be temperature compensated using a temperature probe in the solution. The other alternative is to either warm the solution to room temperature each time or have weaker solutions in the summer and stronger in the winter. The way to get around this is to use the Faraday equation. This allows the exact amount of silver ions to be calculated from the cumulative current applied and is temperature independent. It does however require a microprocessor and complex internal software. This is the approach taken in the Compact 3 unit. The other manual alternative is of course to use a thermometer to measure the temperature and look this up on a graph and plot the estimated time and then use an egg timer. This is not very accurate but will work in a fashion as long as you remember to turn it off when the timer beeps.

As you can see, there is a lot more to producing a quality solution than a battery and two wires. It is important to understand the limitations of each generator type before you buy but you should always ask.

What is the electrode voltage? (should be over 30v)
Is it current limited? (essential)
Is the Current Limit variable? (ideally 0.3mA to 12mA)
Does it have any stirring system? (Will need either electronic or mechanical)
Is it mechanical or electronic? (Electronic is preferred)
What are the stirrers made of? Are they food grade plastic? (PTFE is best)
Are the electrodes 99.99 or at worst 99.90 grade? (Do not use sterling or lower grade silver electrodes)
Does it have an auto-off feature and is the off point PPM variable? (Only the better units will have these features)

Always make sure you ask these questions before you buy a generator.