There are three factors that will determine the quality of the Colloidal Silver that you make. The first is the water that you use. It must be distilled to a high degree of purity. You will need some way to check that the water you are using is pure enough. The distilled water that is sold in grocery stores in 1-gallon containers will generally be good enough. You will still need some way to check it. That can be done with a conductivity meter or by some method included in the design and function of whatever generator we use.
The second factor is the purity of the silver that we use. We want silver ions and preferably no other metals. We want to make a solution containing silver ions, as they are proven to be of great benefit. There are many other metals. However, that can do us great harm. We must take every precaution we can to avoid taking toxic metals into our bodies. That is why we use only 9999 silver wire and insist on a certificate of analysis showing the impurities that are present. In the case of the highest quality silver, the largest impurity will be copper which is not bad in small amounts. That will be the case in silver that comes directly from silver ore that is refined directly. If you buy silver without an assay certificate, it could contain scraps from manufacturing facilities that are alloying silver with any number of other metals. So it's not just a matter of it being 9999, but what is the nature of the other .01%. When you consider the fact that when we make Colloidal Silver , the result is a liquid solution with silver in parts per million (PPM), it makes no sense to try to economize on this. If we consider making Colloidal Silver at a strength of 10 PPM, for example, 1 ounce of silver wire could make theoretically 100,000 ounces or 1500 gallons of colloidal silver.
The third factor is the amount of time that we allow the process. Hydrogen will appear at the cathode (the negatively charged electrode, where electrons enter the water), and oxygen will appear at the anode (the positively charged electrode). Back in the days of the 3 9 V battery and coins, we would wait until we saw a cloud of what we were told were pieces of silver forming in the water and stopping the process soon after that. In reality, the cloud formed by hydrogen and oxygen micro bubbles and meant that the process was in a runaway mode. Disconnecting the batteries at that point would, if you were lucky, get you perhaps a five PPM colloidal silver solution. It would not keep its strength for very long as the larger particles would quickly collide with and absorb the silver ions. A few of us promoted the use of current limiting to prevent the runaway condition. Some of us noted that the higher resistance we used, the better results we obtained in both higher PPM and stability. Many of us, including yours truly, tried every conceivable method of stirring to allow the use of a higher current to speed up the process. All of my efforts in this direction failed. I could not get around the fact that for a given surface area of silver anode only a certain amount of current was allowed. There is a region surrounding the anode called the Nernst diffusion area. To put it simply, it is a region that will only allow a certain density of ions to exist before they agglomerate into larger particles. So for those of you with your setups for making colloidal silver, try reducing the current and allowing more time and let us know the results.