The ABCs of Quality Control, for
A. The Pottery Purifiers
B.  Colloidal Silver & Alternatives
C.  Purifier Systems

Rigorous standards need to be applied in many different aspects of the purifier and it's production.  Any purifier project must take the following kinds of quality control into coinsideration.

At right an inexpensive photo spectrometer is used to show conductivity of water, directly convertable to ionic parts per million. While the tap water in the beaker is 177 ppm, the requirement for the water used to make the colloidal silver is 0.7 ppm.

For the production of the concentrated colloidal silver (CS) that is used for treatment of the pottery purifiers there is a need to use de-ionized, distilled water, which has total disolved solids of under 0.7 ppm.  This degree of purity is much higher than for normal distilled water, in which ppm can be 5.0 to 10.0 or more. 
What needs to be considered in maintaining quality?

A. Pottery/ ceramic purifiers 
The purifiers, candle or disk must give a good appearance, free of cracks or blemishes.  Several good attributes are strength and appropriate permeability.  Whether the surface is rough or smooth is a matter of personal preference, but in general smooth purifiers are preferred for turbid water, rough purifiers for raw water that is already clear.  A normal rate of production failure for the purifiers may be 10% or less.  The pottery clay of the production should be free of sand.  Several important tests necessary for the pottery are performed under C., the purifier system requirements.

B.  Colloidal silver and alternatives
1.  Concentrated colloidal silver
It is necessary to use de-ionized distilled water while doing the production of the concentrated CS.  As in the photo above a photospectrometer can be used to determine ionic ppm content of the water, and/ or for the CS of the production.  A good way of determining total ppm of the colloidal silver is by weighing the silver electrodes, before and after the CS production.
2.  Silver in general
That silver metal used for making electrodes of CS production should be no less than 99.9% pure  This same degree of purity should also be the standard for the production of silver nitrate salts.
The silver electrodes should be weighed before and after the production of concentrated colloidal silver.  This method, and the difference in weight, allow an easy, accurate determination of the ppm, or weight of silver per purifier.
C. For purifier systems, with candles or with particulates
1.  Microbiological results
Every workshop batch of purifiers should have provided an appropriate number of random samples, for micro biological tests. 
2.  Silver presence in the filtered water
From an appropriate, occasional random testing, the first filtered water is tested by atomic absorption in order to determine the amount of silver present.  Verification is required that silver becomes undetectable in the filtrate.
3.  Other water quality tests
Whether for physical chemical results, presence of nitrates or chlorides, etc.
4.  For particulate systems
Considerations for particualtes, in addition to those of a., b., and c., include:  prior to such testing, what particle size distribution, per what column height, will indicate a system of appropriate flow?

D.  Factory safety
Aside from normal safety procedures with kilns and other heavy equipment of the workshop there are several special, safety considerations:
1.  For the particulate grog, all those fine particles that are screened out contain some that are small enough to become air born.  Breathing this fine particulate grog dust should be avoided, since this kind of material remains lodged in the lungs.  Those doing the process should use proper face masks, of the type that filter out this dust.  And a fan or air extractor should be used to pull the dust away from the work station.  Stay away from airborn grog dust.
2.  In working with silver nitrate it is important not to handle this material.  Exposure of the silver salt will deposit this on the skin, or other working materials, like cloth, wood or paper.  With the presence of light the deposited salt stains skin or material with black silver oxide.  And one should not come into contact with the nitrate, whether as acid, fume or salt.  Rubber gloves should be used with silver salts, air extractors or fans are also a requirement.  Proper advice of chemistry professionals is a must concerning production of silver nitrate salts.

Conclusion
It is granted that any particular location of production would face differing requirements for standards.  This brief presentation of ABCs is intended to show some of the important considerations that are necessary.

Please feel free to make contact for questions or observations:
Reid Harvey
pottery@wlink.com.np

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