Production Techniques and Chemistry > Colloidal Silver Production
Perceived color and particle size distribution of Colloidal Silver
kephra:
Colloidal silver produced by the reduction of silver compounds as presented on this site has particles averaging about 14 nanometers in diameter as determined by their surface plasmon resonance. 20 ppm solutions with 14 nanometer average particle size are clear yellow in color, about the color of Johnson's baby shampoo. At higher ppm, the 14nm particles appear brownish in color. At slightly larger size, the perceived color shifts slightly to orange, and at slightly smaller size, it shifts very slightly to having a green tint.
It is not possible to make colloidal silver products having only one particle size. There will always be a spread in sizes which takes the form of a normal Gaussian distribution curve1. Even commercial labs cannot make a product where every particle is exactly the same size without resorting to extreme measures like ultra filtration which explains their astronomical price.
The human eye has cones in its retina which detect blue, green, and red wavelengths. If the brain perceives yellow color, its because the eye detected green and red together in some ratio. More green wavelengths shifts the color toward green, but less red also shifts the perceived color toward green. Because of this, yellow colloidal silver with a slight green tint does not necessarily mean that all the particles are smaller. It means that there are fewer larger particles that would shift the color toward red. It is also significant that the human eye is more sensitive to green than it is to blue and red.2
Because of the way the eye/brain perceives color, it cannot accurately distinguish among samples with different size distributions. IE: A sample with sizes ranging from 12 to 16nm particle sizes will look approximately the same color as a sample with sizes ranging 10 to 18nm. The eye tends to see the average size, but not the size distribution.
1) See https://commons.wikimedia.org/wiki/File:Empirical_Rule.PNG
2) See http://www.physicsclassroom.com/class/light/Lesson-2/Visible-Light-and-the-Eye-s-Response
gary676@gmail.com:
When my wife buys her colloidal silver at the health food store, it is claimed to be 10 PPM but is clear in color. is this wrong?? I have been looking deep into making our own colloidal silver because of the large family I have and also because I want to know we are taking the real stuff, not an imposter? In your Perceived color and partical size section, it states only colors.
kephra:
Clear is bad, it indicates that it is not colloidal silver but is ionic silver if silver at all.
The yellow color on this forum indicates particle sizes around 14 nm. Professional researchers classify their silver nanoparticles by the wavelength of light it absorbs. These nanoparticles absorb blue light leaving green and red, which the eye perceives as yellow. The exact wavelength of blue which is absorbed by 14 nm average particle size is about 410 nm.
Color equates to particle size.
RickinWI:
@ Gary: If your wife is getting it in a health food store it most likely comes in a brown or blue bottle and it is most likely actually IS (Ionic Silver) even though they are (incorrectly) calling it colloidal silver (Colloidal Silver). The brand "Sovereign Silver" is just that. It's 10 PPM IS in a nice blue bottle & it costs ALOT.
WayneInPHX:
--- Quote from: kephra on July 05, 2016, 10:13:16 PM ---Clear is bad, it indicates that it is not colloidal silver but is ionic silver if silver at all.
The yellow color on this forum indicates particle sizes around 14 nm. Professional researchers classify their silver nanoparticles by the wavelength of light it absorbs. These nanoparticles absorb blue light leaving green and red, which the eye perceives as yellow. The exact wavelength of blue which is absorbed by 14 nm average particle size is about 410 nm.
Color equates to particle size.
--- End quote ---
Ok, I am a little confused Kep. I thought the color shows the ppm and tyndall shows particle size. Too big being bright tyndall. Set me straight bro.
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