Lye

For other uses, see Lye (disambiguation).

Pellets of sodium hydroxide.

A lye is a liquid metal hydroxide traditionally obtained by leaching ashes (containing largely potassium carbonate or "potash"), or a strong alkali which is highly soluble in water producing caustic basic solutions. "Lye" is commonly an alternative name of sodium hydroxide (NaOH) or historically potassium hydroxide (KOH), though the term "lye" refers to any member of a broad range of metal hydroxides.

Today, lye is commercially manufactured using a membrane cell chloralkali process. It is supplied in various forms such as flakes, pellets, microbeads, coarse powder or a solution.

Applications

Food uses

Lyes are used to cure many types of food, including the traditional Nordic lutefisk, olives (making them less bitter), canned mandarin oranges, hominy, lye rolls, century eggs, pretzels, bagels, traditional Turkish desserts pumpkin dessert (it creates a hard crust but the inside remains soft). They are also used as a tenderizer in the crust of baked Cantonese moon cakes, in "zongzi" (glutinous rice dumplings wrapped in bamboo leaves), in chewy southern Chinese noodles popular in Hong Kong and southern China, and in Japanese ramen noodles. They are also used in kutsinta, a type of rice cake from the Philippines together with pitsi-pitsî.

In the United States, food-grade lye must meet the requirements outlined in the Food Chemicals Codex (FCC), as prescribed by the U.S. Food and Drug Administration (FDA). Lower grades of lye which are unsuitable for use in food preparation are commonly used as drain de-cloggers and oven cleaners.

Soap making

Lye in the form of both sodium hydroxide and potassium hydroxide is used in making soap. Potassium hydroxide soaps are softer and more easily dissolved in water than sodium hydroxide soaps. Sodium hydroxide and potassium hydroxide are not interchangeable in either the proportions required or the properties produced in making soaps.

"Hot process" soap making also uses lye as the main ingredient. Lye is added to water, cooled for a few minutes and then added to oils and butters. The lye is then cooked over a period of time (1–2 hours), typically in a slow cooker, and then placed into a mold. This method is much quicker than cold process, as it takes several weeks to complete.

The ancient use of lye for soap-making and as a detergent is the origin of the English word, deriving from Proto-Germanic *laugo and ultimately from the Proto-Indo-European root *leue-, "to wash." Relatives in other Germanic languages, besides their words for lye, include the Scandinavian languages' words for Saturday (laugardagur, lördag, lørdag), meaning "washing day".

Household uses

Bottles of alkaline drain cleaners containing lye.

Lyes are also valued for their cleaning effects. Sodium hydroxide is commonly the major constituent in commercial and industrial oven cleaners and clogged drain openers, due to its grease-dissolving abilities. Lyes decompose greases via alkaline ester hydrolysis, yielding water-soluble residues that are easily removed by rinsing.

Tissue digestion

Sodium or potassium hydroxide can be used to digest tissues of animal carcasses or deceased humans. Often referred to as alkaline hydrolysis, the process involves placing the carcass or body into a sealed chamber, adding a mixture of lye and water and the application of heat to accelerate the process. After several hours the chamber will contain a liquid with coffee-like appearance, and the only solid that remains are very fragile bone hulls of mostly calcium phosphate, which can be mechanically crushed to a fine powder with very little force. Sodium hydroxide is frequently used in the process of decomposing roadkill dumped in landfills by animal disposal contractors.

While the lye solution appears to "dissolve" organic material, in fact a chemical interaction is occurring, and the resulting product is no longer "lye" of any kind. The very basic lye reacts chemically with the very acidic proteins that make up the majority of the tissue. Those proteins are acidic because they are constructed of amino acids which ultimately are the "building blocks" of plant and animal matter. DNA is an abbreviation for "deoxyribonucleic acid" and when those acids, which begin to break down and decompose immediately after death when the supplies of sugar and oxygen to cells, the removal of carbon dioxide and alcohol waste products and the cell's function as a tiny nuclear reactor converting chemical energy into heat and electricity cease.

Only when decomposition has progressed to putrefaction and liquefaction, decomposition gases have bloated and split or at least stretched the skin to the point where lye can come in contact with cells below the surface does any significant reaction begin when the decomposition is occurring naturally in an aerobic, atmospheric environment. The primary result of spreading lye on the carcasses of dead animals or human bodies soon after death is dehydration and desiccation of the flesh at and near the surface. The result is essentially "mummification" and the ongoing process of decomposition is actually delayed and slowed when this occurs.

The desiccation contracts the skin and makes it more porous, hair follicles typically fall out and lots of "leaks" form that allow decomposition gases to escape as they form result. If large amounts of lye are used and its properly distributed under, on and around the body, the desiccation process can occur so rapidly and so intensely that the majority of the liquid water and other liquids and fluids in the body are "sucked out" of the body by the lye.

This occurs because the cellular decomposition that begins immediately after death results in the blood becoming very acidic, and large amounts of alcohol are created. Water draws alcohol and the resulting mixture is of lower specific gravity and viscosity than pure water. Alcohol formation in the blood keeps it liquid and preserves the veins, arteries and capillaries so that the blood itself is drawn to the surface even where it would otherwise settle downward due to gravity. The post-mortem lividity that occurs when blood pools on the "bottom" of the body, whichever part that may be, doesn't simply end in the blood pooling and clotting or very slowly drying and/or leaking as the skin decomposes. Instead, it too is drawn out of the body or at least to the skin's surface where it reacts chemically with the lye.

The resulting compound is essentially chemically inert and has a relatively low specific gravity and evaporates away quickly as its formed. When larger amounts of liquid blood leak through if internal gas pressures rise after the skin is somewhat sealed by the reaction processes, the pressure increase may cause larger, longer "leaks" of blood. This blood requires a larger amount of lye to react with, the process occurs more slowly and the chemicals produced will be mainly in liquid form and will leech into the soil or pool on any impermeable surface below it and evaporate away more slowly. The chemical compound produced is ultimately identical in makeup to what is produced if the sealed container/heat method is used, and that method is only "accelerated" because the lye and water mixture prevents dehydration and desiccation.

The resulting chemical compound is not identical, however, since the addition of water results in the creation of a thinner compound with lower specific gravity and reduced energy content per unit of measure. Mentioning energy content makes little since until one considers that as carbon-based life forms consisting primarily of carbon and water, when plant or animal matter decomposes and the resulting chemical reactions break down the acids that form the "organic" mass of the body, the interaction of those acids with a base like lye results in the production of liquid and gaseous fuel as sugar is fermented into alcohol, the alcohol dissolves fats that are ultimately pure stored chemical energy extracted from carbohydrates, much of the liquid water is dissociated into individual hydrogen and oxygen atoms by the intense heat released at the cellular level by those reactions and decomposition and metals and other heavy elements in the body are oxidized and broken down at the atomic or molecular level so their resulting density is low enough that they remain in solution.

When those processes occur in the open air on normal soil in the natural environment, its a slow, seemingly inefficient process but ultimately if the correct amount of lye is used and its properly distributed, eventually total decomposition occurs, the internal heat generated coupled with atmospheric heat make it a net energy producing process rather than an energy consuming process and as decomposition occurs very slowly the byproducts are absorbed into the air and soil where they continue to break down into elements and become "available" for use in "manufacturing" new compounds much more quickly. And if all of the various chemicals and compounds were retained in a closed container process similar to the first but without the additional water and heat needed to "accelerate decomposition" by using the cooking "trick" of creating "reducing" conditions to accelerate the breakdown of complex compounds to extract their ingredients for use in a recipe, the net result after full decomposition using a slower "reduction" technique with energy produced by the chemical reaction between the acidic organic compounds and basic inorganic lye compound, the final result would ALSO be a brownish, liquid.

However, the natural process would produce a much thicker liquid with higher viscosity, higher specific gravity and a lot more chemical energy per unit of volume. And that liquid would be a complex hydrocarbon compound almost identical in makeup, appearance and other characteristics and properties to what is considered by some to be a "pollutant" and by others to be the most useful and valuable natural resource on Earth. That complex hydrocarbon is "crude oil". Reduce a human body to its simplest chemical compound form and "natural state" at "standard" atmospheric conditions, and you have a NON-fossil fuel "synthetic" crude oil. It would be essentially identical in every important and relevant way. Right down to being able to "refine" it into different "fractions" via "electrolysis" using an external heat source. How did and does the Earth do the same thing but without "lye"? Simple. The Earth uses a precursor chemical to "lye" so the process is further simplified. That precursor substance is called LIME. And the process is made more efficient by the addition of groundwater and the application of geothermal heat when it occurs below the surface. Above the surface, good old sunlight works fine.

Fungus identification

A 3–10% solution of potassium hydroxide (KOH) gives a color change in some species of mushrooms:

• In Agaricus, some species such as A. xanthodermus turn yellow with KOH, many have no reaction, and A. subrutilescens turns green.
• Distinctive change occurs for some species of Cortinarius and Boletes

See: Chemical test in mushroom identification

Safety

First aid

Sources recommend immediate removal of contaminated clothing/materials, gently brushing/wiping excess off of skin, and then flushing the area of exposure with running water for 15–60 minutes while contacting emergency services.

Protection

Personal protective equipment including safety glasses, chemical-resistant gloves, and adequate ventilation are required for the safe handling of lyes. When in proximity to a lye that is dissolving in an open container of water, the use of a vapor-resistant face mask is recommended. Adding lye to water too quickly can cause the solution to boil.

Storage

Solid lyes are deliquescents and have a strong affinity for air moisture. Solid lyes will deliquesce or dissolve when exposed to open air, absorbing a relatively large amount of water vapour. Accordingly, lyes are stored in air-tight plastic containers. Glass is not a good material to be used for storage as lyes are mildly corrosive to it. Similar to the case of other corrosives, the containers should be labeled to indicate the potential danger of the contents and stored away from children, pets, heat, and moisture.

Hazardous reactions

The majority of safety concerns with lye are also common with most corrosives, such as their potentially destructive effects on living tissues; examples are the skin, flesh, and the cornea. Solutions containing lyes can cause chemical burns, permanent injuries, scarring and blindness, immediately upon contact. Lyes may be harmful or even fatal if swallowed; ingestion can cause esophageal stricture. Moreover, the solvation of dry solid lyes is highly exothermic; the resulting heat may cause additional burns or ignite flammables.

The reaction between sodium hydroxide and a few metals is also hazardous. Aluminium reacts with lyes to produce hydrogen gas. Since hydrogen is flammable, mixing a large quantity of a lye such as sodium hydroxide with aluminum in a closed container is dangerous—especially when the system is at a high temperature, which speeds up the reaction. In addition to aluminum, lyes may also react with magnesium, zinc, tin, chromium, brass or bronze—producing hydrogen gas.

Further reading

• McDaniel, Robert (1997). The Elegant Art of Handmade Soap: Making, Scenting, Coloring, and Shaping. Iola, WI: Krause Publications. ISBN 0-87341-832-8.

External links

• "Federal Food, Drug, and Cosmetic Act". US Food and Drug Administration.
• "Food Chemicals Codex". United States Pharmacopeia.