Electrolytic Cleaning of Coins and Jewelry - A Detailed Tutorial, page 21
Safety Precautions During Electrolysis: Avoid Toxic Gas Danger, Prevent Accumulation of Hydrogen/Oxygen Gases, Overheating of Power Supply
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5) Avoid Toxic Gas Danger
There are two cases of toxic gas release during the electrolysis:
1) when TABLE SALT is used to prepare the electrolytic solution, and vapors of Chlorine gas is produced during the process (see details on page 15 of my "Electrolytic Rust Removal" tutorial). Chlorine gas can make you really sick quickly.
2) when STAINLESS STEEL anode is used, and Hexavalent Chromium gas is released in the mist directly above the electrolytic bath. Since the anode is not as large as, for example, in the electrolytic rust removal, the Hexavalent Chromium gas is not of a big concern; however, long term inhalation of the vapor increases the risk of lung cancer.
To avoid toxic gas danger, it is probably best not to use salt at all, and use only a minimum amount of stainless material with adequate ventilation and/or breathing protection. And NEVER put your face directly above the electrolytic container!
6) Prevent Accumulation of Explosive Mixture of Hydrogen and Oxygen Gases
When electric current flows through the electrolyte, hydrogen gas is evolved at the cathode (coin), and oxygen gas is evolved at the anode. When ventilation is absent or inadequate, and hydrogen and oxygen gases are mixed at high concentration levels, a highly flammable and explosive mixture is produced. A single spark between a power clamp and an electrode can produce a violent explosion. The fire of explosion burns at about 4280 °F (2360 °C) and may seriously injure you.
To prevent accumulation of explosive hydrogen and oxygen gases, do the following:
• Ensure the electrolysis is conducted in a very well ventilated area or better - outdoors, so that the gasses can escape safely.
• NEVER cover the electrolytic bath with a tight lid, otherwise gas pressure and high concentration levels of gases will build up.
To avoid any risk of explosion, do the following:
1) ALWAYS turn off the power before making adjustments to the setup.
2) Keep ALL potential sources of ignition (flames, cigarettes, torches, etc.) away from the electrolytic setup and surrounding area.
3) If you have already run an electrolysis session indoors, and need to run another session, do not "crank up" the process - wiggle the cathodic power clip to get a spark and establish a good contact (see details on page 22), before you completely ventilate the area.
7) Keep the Electrolysis Setup Undisturbed
Electrolysis should be conducted in a designated place which must meet the following conditions:
• It must be away from human traffic so that no accidental contact can occur.
• It has no access by animals, pets, children, or those who do not understand the danger.
• An outdoors setup should be protected from stray and wild animals, falling branches and leaves, and strong winds.
8) Prevent Overheating of Power Supply
Frequently touch the AC adaptor to determine if it is getting too hot. If so, disconnect it to let it cool off. Such overheating may occur as the fully encrusted coin becomes progressively cleaner. This, in turn, allows for a greater flow of electric current to pass through the adaptor, increasing its temperature. Thus, never leave your electrolysis machine on and unattended for a long while. Leaving the setup plugged and unattended may lead to the adapter's melting or catching on fire.
Although, most of the modern car battery chargers have cooling fans that prevent overheating, it is important to keep voltage and current below dangerous level. Do not cover the car battery charger with a box or bucket. If tightly covered, the charger will overheat with a possibility of burning up as the cooling fan will be circulating hot air only.
If you are unsure of any of the safety aspects described above or unsure about your safety - STOP! Get help before you do something unwise. Use common sense, be smart about what you are doing, and stay safe so you can finish your coin cleaning project and enjoy the results.