Making Jewelry Beautiful
by Dan Schafer
We started manufacturing in Thailand in 1990. In two earlier articles I introduced some of the issues we faced in setting up in Thailand, but we eventually had a good crew of skilled workers. At that point the product we made and sold was called cloisonné jewelry, glass enamel fused to a metal design. The metal we stamped our designs into was copper.
The copper was quite easy to work with, but the finished product had to be plated, because, even though the enamel was beautiful, in order to sell it as jewelry it needed to be plated silver or gold so that it looked like jewelry.
This is where things started to get technical. A farm boy wasn't going to be able to rely just on his common sense. OK, it helped a little to have had some chemistry in high school and a college class with some lab work, but I didn't know the first thing about electroplating. Fortunately for us the company from which we purchased our first basic equipment and chemicals was willing to provide some training for us.
I will summarize what we learned. The job was basic. Theoretically at that point we really only needed to plate two metals: nickel and gold. The nickel was necessary for 2 reasons. First it was a barrier. Gold directly on copper would not last very long because the copper under the gold would eventually start to oxidize. The green roofs of the Canadian government buildings are a clear example of copper oxidation which is nice there but is not nice on jewelry. The second function of the nickel is to make a nice hard and bright surface. So plating the gold on that hard surface gave it a beautiful color that would last for many years.
But plating cannot be done without the bare metal being absolutely clean. Finger prints that no one sees on the bare metal will show up as ugly marks because the plating could not smoothly attach there. So we found we needed ultrasonic waves in a hot detergent solution, then electro-cleaning which electrically creates hydrogen bubbles at the surface of the piece of jewelry as the way to lift any remaining invisible bits of oil from a finger print or such like and finally an acid to clean and "activate" the surface.
But we also needed to take into account that for every solution into which you dip your jewelry some is going to cling to the jewelry as it is pulled out. So we needed to ensure we avoided contaminating a following solution with residue from a previous bath." For example, if one is lifting a rack of jewelry out of a soapy bath and the next step is an acid dip you need to make sure you are not carrying soapy solution into the acid.
A counter-flow rinse tank. Dan and Bow checking gold plating.
The answer we learned is to rinse, rinse, rinse in what are called counter-flowing tanks. The jewelry is going one way and the water flow the other. That is, the first tank will always be relatively the "dirtiest" because it is really the end of the water flow. Speaking flow-wise, it is the last tank in a series of 3 where fresh water -- in most cases ultra-pure deionized water-- flows into number 1, overflows from there into 2, from there into 3, and from there to the drain. And our plating racks get rinsed 3, 2, and 1.
That introduction indicates a little of what technical things we needed to learn. So even though we were not experts, if we followed the basic principles we were taught, everything went well, amazingly so.
However, a more immediate issue we had to face was that however clever we were with our rinse water there always is some chemical remaining in the rinse water when it became waste water. As you may know if you have read my earlier articles, our factory was not in an industrial zone. We had set up in a longan fruit orchard, far from any industrial infrastructure like waste water treatment. But one thing that often goes with longan orchards is a pond which had been dug as a source of water for the fruit trees, and ours was not an exception. Since our property had no provision for drainage to anywhere, our waste water eventually would have to go into that pond.
We certainly didn't want to be the people whose industry contributed to polluting the natural environment -- not just for our reputation's sake, but on principle. We weren't so focused on our own immediate need that we would take shortcuts that eventually created problems. Actually, even then we hoped manufacturing in Asia could be a means to improve things -- improve the standard of living of the people who came to work for us, and help them to develop new skills and broader understanding. So here we faced a challenge both in solving the problem and in having a positive influence on our employees and our neighbors in the community.
So, go back to the drawing board. Certainly there must be a way to get the chemicals out of the water. There has to be a way to discharge only clean water.
I learned that the first thing to accomplish that is to take into account pH of the effluent. Certain things will happen in a low pH or acidic liquid that won't happen in a high pH or base solution. So, the best way is to keep separate these waste streams at source. That meant a big plumbing job and some big holding tanks to store those two kinds of effluent.
In order to eventually send the water to the pond we needed to get everything toxic out. Like most things we meet, there likely has been someone else who has done something like this before. So with a little research we learned that we could invest in equipment to precipitate virtually all the contaminant out of the low pH solution. The system stirred the liquid in a mixing tank, metered out a high pH solution into the tank, and continually monitored the pH of the agitated liquid to achieve the set level. Again, it was amazing how well that worked. When the tank holding the treated water was full the equipment would shut down. Then slowly the precipitated solids would settle out overnight.
In the morning there would be clear water above and sludge below. So when we came to work the next day, we opened a PVC valve at the bottom until all the sludge slowly flowed through a PVC pipe to one of two sludge beds we had created. Then we siphoned the clear water out to the pond. We could alternate sludge beds over a period of time so that one would have a chance to dry and be packed up for hazardous waste disposal, while we used the other.
I will leave for another time the other waste stream -- the high pH, but the nice thing about it we learned was that virtually all the toxicity there could be oxidized out.
So the answers weren't always easy to find, but as we persisted and did our research it looks like we won.
So now, almost 30 years later, our pond is still there and stocked with fish. It has its ups and downs (literally) with the dry and rainy seasons, but with its aerating fountain (see photo) it has been a feature of our campus.