Hazards in Etching

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Contact with acid is the main concern in etching, especially when preparing acid etching solutions. Concentrated acids are the most dangerous, protective clothing and goggles must be worn; PVC, neoprene rubber, latex neoprene or butyl gloves are all suitable for use with both concentrated and diluted acids (such as nitric), they do not give absolute protection and should be replaced frequently.

Fumes. Acid fumes can be extremely dangerous if inhaled, good ventilation is required at all times. Inhaling the fumes can cause irritation to the lungs, impair breathing causing nitric acid poisoning, or pulmonary oedema -a disease that leaves fluid on the lungs.

Burns. ALL acid burns, contact with the skin should be avoided at ALL times. If contact is made with the skin wash immediately with clear water, cover the burn and seek medical attention.

Nitric:- gives off nitrogen dioxide gas when etching zinc or copper plates, can cause bronchitis or emphysema from chronic exposure to small quantities.

Potassium Hydroxide:- A powerful alkali, irritation of eyes & lungs and can damage the nose. Can cause dermatitis.

Formaldehyde:-Is a sensitizer, emits highly irritating fumes especially when heated, avoid skin and eye contact.

Ferric Chloride:-Is an iron salt mixed with water to make an etching solution where it hydrolyses to produce hydrochloric acid, which is irritating to the skin and eyes. Safer than Dutch Mordant.

Dutch Mordant:- Mixture of hydrochloric acid, potassium chlorate and water. Chlorine gas is given off, which is toxic and can cause irritation to the mucus membranes, eyes and lungs.

Liquid hard ground:- Contains disunite, can cause photosensitisation of the skin, irritant to skin and mucus membrane and depress central nervous system.

Turpentine:-Flammable, can depress the central nervous system and cause irritation. It is also suspected of causing kidney damage.

Mentholated spirits:- Highly flammable, can be absorbed through the skin.

Turpentine:-Flammable, can depress the central nervous system and cause irritation. It is also suspected of causing kidney damage.

Printmaking inks are harmless but some do contain toxic metals, glycol ethers and other hazardous chemicals.

Antimony Pigments:- Antimony orange, Naples Yellow

Arsenic:- Emerald green, Paris green, Cobalt, Violet.

Cadmium sulphide:- All cadmium pigments.

Chromium:- Green viridium, Chromium yellow.

Cobalt:- Cobalt violet, Cobalt yellow.

Lead compounds:- Flake white, Chrome yellow, Naples yellow, Umbers.

Manganese dioxide:- Umbers

Mercuric sulphide:- Cinnabar, Vermillion.

Molybdenum:- Orange.

Selenium:- Cadmium red.

Acid:-

If ferric chloride is not adequate for your etching, it probably means using nitric acid or Dutch Mordant. These are strong acids and require a safety shower as well as protective clothing.  Nitric acid has additional hazards, as it is an extremely strong oxidizing agent. It will react violently with organic compounds (solvents, acetic acid etc.), and should therefore be stored in an acid-safe cabinet away from  oxidizable materials.  Nitric acid gives off various nitrogen oxide gases, including nitrogen dioxide, a strong lung irritant that can cause emphysema.  Local exhaust ventilation, such as a slot hood or a fume hood, is absolutely necessary for these etching baths to remove the noxious gases.Large quantities of concentrated acid under pressure are very dangerous because they might rupture the container.  Dutch mordant is typically 10% hydrochloric acid in water with potassium chlorate added.  The potassium chlorate would readily react anything in the waste solution, grease, dirt, etc.  The gas in the closed jerrican was either chlorine or chlorine dioxide.