Alcohol

Jul 10

A discussion on the use of alcohol for wood drying and related dangers.

A member of the Calgary Woodturners Guild mentioned at the Feb 2014 meeting that he used Methyl Hydrate to dry green bowl blanks. After rough turning to ½” thick, and submersing them for 24 hours, he then wraps them in brown paper to let dry for up to four months. He has had great success in obtaining bowl blanks that have not cracked or warped for him.

This drying method generated a discussion on the use and safety surrounding the use of “alcohol” in the shop. It was obvious that most of the members were unaware of the types of alcohol and the proper use of each. Terry Golbeck, of Black Forest Wood Company, relayed the events of one of his former customers. Apparently the customer was applying shellac by hand as a finish without using any precautions. The methanol solvent was absorbed through his skin leading to his death due to methanol poisoning.

This article is intended to help clarify the consequences and safe use of different types of alcohol for woodworkers. Just because you can buy things at a store does not mean they are safe to use without precautions. If nothing else please read the following conclusions. After that more details on the chemistry and uses of the different alcohols are provided.

Conclusions

There are numerous alcohols but the three most common are methanol, ethanol and isopropanol. Each has several common names but ALL are TOXIC.

Methanol (C2H5O, Methyl Hydrate, Wood Alcohol, Wood Spirit or Methyl Hydroxide) is the most toxic. The MSDS sheet states:

“ May be harmful if inhaled, absorbed through the skin or swallowed. Mild central nervous system depressant. May cause headache, nausea, dizziness, drowsiness, and incoordination. Severe vision effects, including increased sensitivity to light, blurred vision, and blindness may develop following an 8-24 hour symptom-free period. Coma and death may result….Metabolic acidosis and severe visual effects can occur following an 8-24 hour latent period. Coma and death, usually due to respiratory failure, may occur if medical treatment is not received.”

Ethanol (C2H60, Ethyl Alcohol, Grain Alcohol or drinking alcohol). Ethanol is a psychoactive drug and is one of the oldest recreational drugs still used by humans. Ethanol can cause alcohol intoxication when consumed. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a solvent, and as a fuel. In common usage, it is often referred to simply as alcohol or spirits. Based on its abilities to change the human consciousness, ethanol is considered a psychoactive drug. Death from ethanol consumption is possible when blood alcohol level reaches 0.4%. A blood level of 0.5% or more is commonly fatal. Levels of less than 0.1% will cause intoxication, with unconsciousness often occurring at 0.3–0.4%. the table below shows the effect at different blood levels. Remembering that the legal impaired driving limit is 0.08%

  
    BAC (g/L)
    BAC (% v/v)
    Symptoms
  

    0.5
    0.05%
    Euphoria, talkativeness, relaxation
  

    1
    0.1%
    Central nervous system depression, nausea, possible vomiting, impaired motor and sensory function, impaired cognition
  

    >1.4
    >0.14%
    Decreased blood flow to brain
  

    3
    0.3%
    Stupefaction, possible unconsciousness
  

    4
    0.4%
    Possible death
  

    >5.5
    >0.55%
    Death
  

Isopropanol (C3H8O, Isopropyl alcohol, secondary alcohol or Rubbing alcohol). The substance is toxic to kidneys, liver, skin, central nervous system. Repeated or prolonged exposure to the substance can produce target organ damage. Isopropyl alcohol and its metabolite, acetone, act as central nervous system depressants. Symptoms of isopropyl alcohol poisoning include flushing, headache, dizziness, depression, nausea, vomiting, anesthesia, and coma. Poisoning can occur from ingestion, inhalation, or absorption; therefore, well-ventilated areas and protective gloves are recommended. Around 15 g ( ½ Oz.) of isopropyl alcohol can have a toxic effect on a 70 kg (155 Lb.) human if left untreated. However, it is not nearly as toxic as methanol or ethylene glycol. Isopropyl alcohol does not cause an anion gap acidosis unlike ethanol and methanol. Isopropyl alcohol does however, produce an osmolal gap between the calculated and measured osmolalities of serum, as do the other alcohols. Overdoses may cause a fruity odor on the breath as a result of its metabolism to acetone, which is further metabolized to produce the nutrients acetate and glucose. Isopropyl alcohol is oxidized to form acetone by alcohol dehydrogenase in the liver.

Safety considerations

Alcohols may be used safely but proper handling and storage are required.

Personal Protection for use with Methanol

Eye/face Protection: Chemical safety goggles. A face shield may also be necessary.

Skin Protection: Chemical protective gloves, coveralls, boots, and/or other chemical protective clothing. Safety shower/eye-wash fountain should be readily available in the immediate work area.

Hand protection: Butyl or Viton ®. Since methanol is recognized as a skin absorption hazard, check with glove manufacturers for appropriate glove material, thickness and resistance to breakthrough.

Respiratory Protection: Respiratory protection should be worn when there is a potential to exceed the exposure limit requirements or guidelines. Use an approved positive-pressure full-face self-contained breathing apparatus or a full-face supplied air respirator.

Storage: Store this material in a cool, dry, well-ventilated area away from oxidizing materials and corrosive atmospheres, in a fireproof area. Keep amount in storage to a minimum. Storage area should be clearly identified and clear of obstruction. Do not store below ground level, or in confined spaces. Have appropriate fire extinguishers and spill cleanup equipment in or near storage area. Store away from strong oxidizers, mineral acids and metals.

Discussion

The properties associated with Alcohols are:

A colourless liquid, with a mild, characteristic alcohol odour when pure. Readily absorbs moisture. Burns with a clean, clear flame, which is almost invisible in daylight, or a light blue flame. Alcohols are useful as solvents.

Alcohols that are under consideration include Methanol, Ethanol and Isopopanol. Because you can drink Ethanol, the government wants its taxes, so it is expensive. Isopropyl alcohol dissolves a wide range of non-polar compounds. It also evaporates quickly and is relatively non-toxic, compared to alternative solvents. Thus it is used widely as a solvent and as a cleaning fluid, especially for dissolving oils. Together with ethanol, n-butanol, and methanol, it belongs to the group of alcohol-based solvents.

Which brings us to Methanol. Methanol has a high toxicity in humans. If as little as 10 mL of pure methanol is ingested, for example, it can break down into formic acid, which can cause permanent blindness by destruction of the optic nerve, and 30 mL is potentially fatal. It is used to denature Ethanol to prevent human consumption. However it is widely used in common things such as windshield washer fluid, gasoline de-icer, camp fuel (gelled and brand named as Sterno). The largest use of methanol by far is in making other chemicals. About 40% of methanol is converted to formaldehyde, and from there into products as diverse as plastics, plywood, paints, explosives, and permanent press textiles.

All chemicals are described with Material Safety Data Sheets (MSDS). You are encouraged as the user of a product to read and understand the entire MSDS, and follow the precautions specified unless the conditions of use necessitate particular procedures or methods. These sheets include information on the hazards, composition, first aid, fire fighting methods, handling and storage, exposure controls/personal protection, physical properties, stability and reactivity, toxicological information, ecological information, disposal considerations, transport information, regulatory information and other information.

These sheets are readily available from the dealer selling the chemical or from a web search. A link below is given for each of the alcohols above.