This article page is from a segment of the Metalsmith Magazine (1983 Summer), “Health Hazards”, discussing questions from readers and answers provided by Linda herself.


Dear Linda,

You are doing a great service by persevering the study of health hazards in your column in Metalsmith. The language of toxicology tends to be arcane, to say the least, and you apparently have the tenacity to not let it get you down. Congratulations!

Now, having said that, and recalling that one should beware strangers from the east bearing gilts (or unsolicited compliments), yes. I do have a question. It is probably a tough one. Have you looked into the subject of the disposal of plating salts, especially cyanides?

Ganoksin is sponsored by

There seem to be two viewpoints:

  1. What is legal and responsible (EPA approved, as well as local ordinance, etc.); and
  2. What is convenient—it is probably possible to flush a pound of cyanide down the toilet and get away with it in many towns around the country. but this is irresponsible (and if you have a septic tank, it is plainly foolish).
  3. Then there is the process of “bombing”—brightening gold using hydrogen peroxide and sodium cyanide solution. What do you do with the leftovers, not to mention the washings?

I live in a rural area where I could, if I wanted to, simply dump the stuff on the ground and get away with it, but I have no desire to start my own private Love Canal. Obviously, gold salts go back to the refiner, they are not interested in copper or silver leftovers, or cyanide used in metal surface treatments. What should be done with used cyanide solutions? Do you have any suggestions? I’m sure many of your readers would be interested.

Several things that I would like to point out:

  1. Working with, and attempting to neutralize, acids will produce harmful acid mists and fumes. Adequate ventilation should be used, and the craftsman should wear a respirator, rubber gloves and eye protection. Many home/studio ventilation systems have not been designed to withstand the corrosive nature of acid mists and fumes. All personal protective equipment should be specifically for acid mists, it is not effective to wear a respirator or rubber gloves that were designed for another purpose.
  2. Do not just put a jar of acid waste material in your trash can! It can become an inconsiderate unknown hazard lo the garbage collector and the people who work at the sewage-treatment facility. Check for local regulations on this by calling your local municipal sewage-treatment facility.
  3. Undiluted acid that has not been chemically neutralized will probably be corrosive to your plumbing system. It is also very likely that even the neutralized acid solutions, since they are usually saline in nature, will also be corrosive to your plumbing system.
  4. Very large quantities of acids can be handled by companies who specialize in hazardous waste disposal. They will require the waste to be sealed in a barrel which they will pick up and transport to a Class I (or Class A) land fill. At the land fill, if the waste is in liquid form, it must be drained from the barrel. Class I land fills are designed and built to prevent hazardous liquids from leaching into the ground and contaminating the local water table.

The major drawback to this type of hazardous waste disposal is that most of us do not work with large enough quantities to economically justify this means of disposal. Some of us would be willing to personally take our own small quantity of toxic waste to a Class I land fill, but they are not always conveniently located. According to my sources, none exists in the whole state of Arizona or Colorado. So, again, the solution seems to be to contact your local waste-treatment facility.

Here are a few things I have found out on my own:

  1. The Environmental Protection Agency has a variety of toll-free “hot lines.” The number for the “Hazardous Waste Office’ is (800) 424-9346.
  2. I was told by the EPA/HWO that unless you exceed 1000 kilograms of hazardous waste discharge in any one month, federal laws do not apply to you. (Local laws may differ but probably are similar.)
  3. It is legal, but probably unwise to flush wastes into a septic tank. It is more prudent to take the acid that you wish to dispose of to the nearest municipal sewage treatment plant, or flush neutralized and diluted acids into a system that leads to a municipal sewage treatment plant. lf that’s not possible, there are simple chemical manipulations that can make most acid wastes less harmful.

— Carroll A. Smith


Dear Carroll,

Thank you for the compliments, questions and results of your inquiry. Upon calling the EPA/HWO toll-free number, I received the same information that you did. However, when I called the San Francisco office of the EPA, I spoke with Fred Kreeger who was more specifically helpful. He also put me in contact with a chemist at the San Francisco EPA office who was very informative.

Ganoksin is sponsored by

Most of us artist/metalsmiths/goldsmiths/silversmiths do fall into the category they classify as “small quantity users,” and thus we are exempt from EPA regulations. Nonetheless, I’m sure many of us would like to do what is healthy, safe and correct for ourselves and the environment.

It was also suggested to me that we should ask our supplier about disposal, neutralizing or recycling acid wastes. But frequently I find that the supplier is nothing more than a salesman with little, or no, knowledge about health and safety. Perhaps we could propose that the supplier set up disposal/recycling in conjunction with his distributor. Since it would require storage space and supervision time, the supplier could figure out a reasonable fee to charge for facilitating this service. There really is no reason for us to expect any supplier to provide this service merely for the convenience of his customers. By charging a fee, the supplier can relieve the craftsperson of the disposal dilemma and make it worth his time and overhead expense for the storage space required.

To dispose of the acid waste material in this way, one would return it back to the supplier in the same container in which it was purchased, sealed with a tight-fitting lid. Or, in the case of something like Sparex, which is purchased in a dry, granular form, the supplier could provide an appropriate container for returning the liquid waste. Many stores will not have the integrity or sense of responsibility to the environment, or to their customers, to want to be involved in this procedure—with, or without, the profit motive. It is within our power, as consumers, to insist that our suppliers provide this service. The craftsman should also understand that whatever it costs the supplier to provide this service, assuming it is realistic and reasonable, it will surely be more economical and practical than each individual craftsman trying to dispose of the acid waste material independently.

Ganoksin is sponsored by

As I further elaborate on the specific acids, and the recommended means of neutralizing them, keep in mind the above paragraphs 1 and 3, and that when acid is to be diluted with water, always add the acid to the water, never add the water to the acid. The following procedures were recommended to me by a chemist with the EPA, however, it must be understood that each individual craftsman undertakes to work with acids in his own studio at his own risk. These procedures are intended only for neutralizing and disposing of very small quantities of acid waste solution, i.e., one quart maximum.


This acid is primarily used by enamelisls to etch glass. In most circumstances, it may be used up until it evaporates, then, rinse out the container with lots of fresh water. The container may then be disposed of with your ordinary trash.


What you are essentially doing when neutralizing hydrochloric acid is converting it to sodium chloride (ordinary table salt). Fill a large, 1 gallon, plastic pitcher half full of water (1,42 gallon H20). To this, slowly add a maximum of 1 cup of hydrochloric acid solution. In another, very large, 3 gallon, plastic basin, place about ¼ to ½ cup baking soda and 1 gallon fresh water. Into this basin, slowly pour the diluted acid solution from the first, 1 gallon, pitcher. Pouring it slowly will help to minimize the fizzing. bubbling and fumes. The mists, or fumes, produced by this fizzing is primarily carbon dioxide. Once the fizzing has subsided, the contents of the large basin may then be flushed, with copious amounts of cold running water, down the drain.

Ganoksin is sponsored by

Sulfuric Acid, Sparex and Nitric Acid

These can all be diluted, neutralized and disposed of in the same manner as hydrochloric acid (in separate containers, and not at the same time, of course). This process of neutralizing converts sulfuric acid to sodium sulfate, a compound similar to epsom salts. Nitric acid is converted to sodium nitrate which is used as a commercial fertilizer.

The chemist that was advising me had had no experience with Aqua Regia (nitric and hydrochloric), he advised me to consult with a chemist who specialized in explosives when I inquired about the possibility of neutralizing this acid combination. He also cautioned that the fumes could be very detrimental to your health, and could cause cellular damage which may lead to lung damage.

Sodium Cyanide and Cyanide

These would both have to be taken to a publicly owned treatment works (municipal sewage plant) or returned to a supplier. Sodium cyanide is an inorganic salt, not an acid. Cyanides have definite toxic properties; this is what is used in the “gas chamber.” Do Not Ever combine cyanide, or its waste, to any other acid, or its waste—this would be deadly, Cyanide, when mixed with any other acid will form hydrogen cyanide which is an odorless gas that is deadly. (This could happen accidentally if a piece was not thoroughly rinsed off and neutralized between a pickling process and a cyanide process.) Sodium cyanide mixed with tap water will produce fumes that will make you violently ill. Drinking this would produce death—Jonestown style. So, please do not dump cyanides down the toilet or sink, or leave any contaminated container around that might accidentally be used for drinking. The advising chemist also couldn’t imagine anyone working with the combination of hydrogen peroxide and sodium cyanide, as you mentioned that you use in the “bombing” procedure, He sounded quite horrified, stressed the danger and recommended using both ventilation and a respirator.

Ganoksin is sponsored by