Copyright © 2011 / W.G.Peters — Nov 27, 2011 — updated 6/24/2012

I am constantly looking for new processes and substances to use for making colloidal silver.  Here are my latest thoughts.


The electrolytic process for making colloidal silver requires an electrolyte to work.  Even pure distilled water with nothing added to it acts as a weak electrolyte because a very small amount of pure water disassociates into H+ and OH- ions.   You might say that a certain amount of water dissolves in itself as hydrogen hydroxide.  A liter of pure water will contain 10-7 moles1  of hydrogen ions, and 10-7 moles of hydroxide ions.  This amounts to 0.00018 milligrams of hydroxide ions, but this tiny amount is enough to make silver hydroxide when you put silver electrodes in the water and connect them to a battery.  These hydrogen ions and hydroxide ions are the current carriers which allows current flow through the electrolysis cell, but so few carriers result in a very weak current.  A weak current results in a long process time.

Aside from the long process time, using the hydroxide inherent in pure water as the electrolyte has another problem.  The amount of hydroxide is not constant, but increases as the amount of silver hydroxide increases.  This creates a run-away process that gets faster with time, and therefore is difficult to control as anyone who has used this simple process can attest.

We can solve these problems by adding an appropriate electrolyte to our water.  A useable electrolyte must have certain characteristics.  It must be non-toxic above all else.  It must not form any toxic byproducts.  It must form a soluble compound with the anode metal.  It must dissociate in water (ionize). Its positive ion should not plate out onto the cathode.  It should be inexpensive, and readily available.  These requirements reduce the number of choices considerably.

In choosing the specific compound to use, toxicity is paramount.  Luckily substances normally found in human physiology are good candidates.  Chlorides, citrates, gluconates and hydroxides and carbonates are all non-toxic anions3 especially in the low concentrations we need.  Chlorides are everywhere in the body, and citrates are an integral part of the citric acid cycle which provides our energy.  Gluconates are commonly found in foods.  Hydroxide is a natural constituent of water.   The body is very adept at handling these substances.  However, gluconates are not readily available for most people, so I take them out of the list.  Citrate is a good choice if the goal is to make ionic silver, as it is more soluble than silver hydroxide or chloride.

There are only two very common bio-compatible cationic substances which will not plate out onto a cathode.  They are sodium and potassium.  Both of these ions react strongly with water as soon as they are reduced to metal at the cathode, and create hydroxides which are water soluble.  So, the sodium or potassium stays in solution as ions.  Because of this, a sodium or potassium salt would be ideal for making colloidal silver electrolytically.  An added benefit of using sodium salts is that it is self replenishing.  The sodium ions that contact the cathode are immediately reduced to sodium metal, and then react with the water to become sodium hydroxide.    The net result is that the electrolyte is never used up.

For these reasons, my first choice of an electrolyte is sodium carbonate, commonly known as washing soda.  It is cheap, readily available, and it works extremely well for making colloidal silver.  It is also safe to handle.  Everyone has consumed sodium carbonate, it is what results from heating baking soda, so is a common ingredient in baked goods.

When using sodium carbonate as an electrolyte, the MINIMUM theoretical voltage needed is 3.5 volts.  Below this there is not enough voltage to reduce the sodium at the cathode and oxidize the silver at the anode.  This comes from the electrochemical series which describes the voltage a metal creates when used with a different metal in an electrolytic cell (battery).  Experiments I have conducted seem to confirm this.  The sodium ion requires -2.71 volts to force an electron to it, and the silver atom requires 0.8 volts to remove an electron from it.  So the total is 3.51 volts.  In practice, a higher voltage is necessary because voltage is lost in the bulk fluid between the electrodes.  In practice, the voltage should be several times this minimum to account for the voltage lost in the electrolyte.  I have demonstrated making CS with only 7.5 volts on the electrodes with satisfactory results, but I have found that higher voltage is always better. However, the improvement is not linear.  IE: 10 times the voltage does not provide a ten fold increase in quality or efficiency.  Anything over 20 volts is probably not very beneficial.  Of course, the optimum results also depends on the temperature and geometry of the electrodes.  What is optimum for my setup probably won’t be for someone else’s.  As a minimum the voltage should be at least 10 volts.  However minimum voltage depends on the spacing of the electrodes and 10 volts is for a spacing of 1.5 inches.

Using sufficient sodium based electrolyte keeps most of the silver from plating onto the cathode.  The cation with the lowest redox potential from the electrochemical series will selectively plate out.  Since sodium’s redox potential is 2.71 and silvers is .8, the sodium ions keep the silver from plating onto the cathode.

Reducing Agents:

Reducing agents are necessary if one wishes to make non-ionic colloidal silver.  While heat alone can accomplish this, the process is slow, and not always complete.  Also, it is very difficult to make higher ppm concentrations of silver using heat alone.

As with electrolytes, the non-toxicity of a reducing agent is the first consideration.  I pondered this for a long time until I realized that any food we eat will undergo chemical oxidation by the body.  The body knows quite well how to handle the oxidized byproducts of metabolism.   This means that if the food is non-toxic, so will be its reduction/oxidation products.  Luckily, there are many sugar based and other food products which are reducing agents and work with silver.  The quality of the product differs with choice of reducing agents in that some produce more consistent particle sizes, some work faster, and some produce more stable product. Agents which have shown to work are glucose, fructose, corn syrup, invert sugar, maltodextrin, honey, and cinnamon.  Tea is also a reducing agent, and has been shown to reduce gold.  So far, the best I have found is cinnamon extract, with my second choice being clear corn syrup, and honey being my least favorite because of all the foreign matter it contains.  Lactose and maltose may also work, but I have not tested them.  Ordinary table sugar (sucrose) does not work, nor does ordinary starch. One common food item I would like to try is coffee.  Yes, coffee.  Amateur photographers who experiment with their chemistry know that coffee2 will develop film, and that means it will reduce silver.

When the process is complete, and all of the silver ions are reduced, the solution will contain nothing toxic.

For any of these agents to work, the pH of the solution must be basic (above pH 7).  Otherwise, the reducing agent will be expended reducing hydrogen ions.  Using sodium carbonate as an electrolyte automatically raises the pH sufficiently to activate the reducing agent.   This requirement would seem to put a lower limit on the current used for the electrolysis, as the voltage minimum would not be reached if very low currents were used.   This limit would also depend on the electrode geometry, as decreasing the electrode area will have the effect of raising the cell resistance, therefore requiring a higher voltage for a given current.

1)   A mole of any substance contains approximately 6 x 1023 molecules, and weighs the sum of its atomic weights in grams.
2)   Coffenol developer contains Folgers instant coffee, vitamin C, and baking soda.
3)   Anions are  ions which are more negative than the anode.  Cations are ions which are more positive than the cathode.
4)   It gives the salt and vinegar flavor to certain brands of potato chips.


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