Yes, I agree I have overcomplicated my setup by using two silver electrodes, there is still a lot of room for improvement. Thanks for the pointers.
I would like to get a little deeper into the color and stability issue. It is an issue few people write about, other than saying their silver colloid is 100% stable, or has been stable over a period of a year... but in all cases it is likely that some change takes place in the colloid, right? I have produced colloids in the 15-20 ppm range over the past 6 months with several different protocols, and I have noticed that some seem totally stable, no visible color change over a 4-5 month period. I always keep a small sample in clear glass and daylight conditions.
Some samples show significant red shift after weeks and months. The 80 ppm colloid produced last week that I mentioned in a previous message also seems to show some red shift.
Red shift is a bit tricky, as I understand, because color can be related to particle size (red shift between 2.2 and 12.5 nm and blue shift above 12.5 nm and again a red shift over 20-30nm). Other research relates red shift to change in particle shape (yellow for spherical particles, green and blue for rods and triangles, etc.), with spherical particles being the smallest (largest surface area). I guess the color change, in any case, is related to increased agglomeration, due to influence of radiation (light, heat), as it happens over time (I don't suppose we could count with a spontaneous particle size reduction).
But what I was wondering about specifically, is about the influence of the amount of reducing and capping agent (I agree that an excess of glucose does not seem to have a bad influence, or even seems to have a positive influence on shelf life), and the time you leave the colloid cooking after cutting off the energy to the electrodes? What would be your explanation about red shift in this short period of time? Lack of capping? Overcooking? Excess agglomeration due to other processes?