Step 6: Filtering the gold foils.

Picture of Filtering the gold foils.
Items required
  • coffee filters
  • filter holder
  • 60oz pickle jar. or glass container large enough to contain waste acids.

Simply Poor the contents of the two gallon bucket into the pickle jar using the coffee filters to catch any foils that are floating on the surface of the acid. Once you have pored off all the acid you will be left with a pile similar to what is in the picture.  scoop these from the bucket into another container for future processing.

Congratulation you are about 50% finished. **********   

************************************* HEALTH WARNING ***************************************

Melting at this stage may lead to the following health hazards.

Inhalation of zinc oxide fumes can occur when welding or cutting on zinc-coated metals. Exposure to these fumes is known to cause metal fume fever. Symptoms of metal fume fever are very similar to those of common influenza. They include fever (rarely exceeding 102o F), chills, nausea, dryness of the throat, cough, fatigue, and general weakness and aching of the head and body. The victim may sweat profusely for a few hours, after which the body temperature begins to return to normal. The symptoms of metal fume fever have rarely, if ever, lasted beyond 24 hours. The subject can then appear to be more susceptible to the onset of this condition on Mondays or on weekdays following a holiday than they are on other days.


Beryllium is sometimes used as a alloying element with copper and other base metals. Acute exposure to high concentrations of beryllium can result in chemical pneumonia. Long-term exposure can result in shortness of breath, chronic cough, and significant weight loss, accompanied by fatigue and general weakness.


Mercury compounds are used to coat metals to prevent rust or inhibit foliage growth (marine paints). Under the intense heat of the arc or gas flame, mercury vapors will be produced. Exposure to these vapors may produce stomach pain, diarrhea, kidney damage, or respiratory failure. Long-term exposure may produce tremors, emotional instability, and hearing damage.


Inhalation and ingestion of lead oxide fumes and other lead compounds will cause lead poisoning. Symptoms include metallic taste in the mouth, loss of appetite, nausea, abdominal cramps, and insomnia. In time, anemia and general weakness, chiefly in the muscles of the wrists, develop. Lead adversely affects the brain, central nervous system, circulatory system, reproductive system, kidneys, and muscles.


Cadmium is used frequently as a rust-preventive coating on steel and also as an alloying element. Acute exposures to high concentrations or cadmium fumes can produce severe lung irritation, pulmonary edema, and in some cases, death. Long-term exposure to low levels of cadmium in air can result in emphysema (a disease affecting the ability of the lung to absorb oxygen) and can damage the kidneys. Cadmium is classified by OSHA, NIOSH, and EPA as a potential human carcinogen

Disposing of your waste acids.

Place your acid in a separate container, I choose used 2 liter or 3 liter bottles,   Label these bottles as CLCu2 with a black sharpie marker. under that write may also contain trace amounts of NICKLE and ZINC, BERYLLIUM, CADMIUM and LEAD.   You can take these items to your local hazard roundup or recycle your acids with a method I plan on detailing in another instructable.

DO NOT dump your acids down the drain or on the ground.  it is IMPORTANT to be responsible with wastes.

Cryxis9911 months ago

I will be doing this for a school experiment and was wondering where to take the waste, would a normal waste disposal place accept the glass jars full of acid and metal or are there specific places to take this acid?

Also when combining the muratic acid and hydrogen peroxide about how violent is the reaction? would I be able to do that in a fume hood?

EricTipton1 year ago
Hey Railes, great post. I'm taking my time in learning, but one recent question I have is... is there a limit on how many fingers you have to use? I have about a half pound right now, and would rather do a full pound all at once when I get there. Is this possible? I feel like I read that you are only supposed to do 150 grams at a time, or something like that, but maybe that was to an entirely different process. Would you have to let it sit longer possibly? Thanks for any insight, I really appreciate it. -Eric
Railes (author)  EricTipton1 year ago
i only used a small amout for the demo, batchs can be done at any quanity.
Okay that's great news, thanks a lot.
Wait, couldn't you just take the gold foil that is 80% gold and 20% copper, and heat it till it melts and scrape off the slag(copper)
Railes (author)  Coolnventions2 years ago
Nope, not unless you have exteme precision induction melters.
harmless202 years ago
Excuse me Railes but may I ask you how you recovered the gold from the coffee filter? I've seen people just burn the filter, if you could help me it would be greatly appreciated
Railes (author)  harmless202 years ago
Scorch the filters, then treat the ash with the second chemical bath.

You need a great deal of filters before they are with doing this with. You would be best served by making sure no foils linger if possible.
xxx_mox_xxx2 years ago
so is there gold in the first bath too that we can recover from? if so how do you recover it from the first bath? by bath i mean the clcu2. is there gold in the clcu2?
Railes (author)  xxx_mox_xxx2 years ago
No gold is dissolved with the first bath.