Leaches / Lyes
Lye is a corrosivealkaline substance, commonly sodium hydroxide (NaOH, also known as 'caustic soda') or historically potassium hydroxide (KOH, from hydrated potash). Previously, lye was among the many different alkalis leached from hardwood ashes.[1] Today lye is commercially manufactured using a membrane cell method.
Solid dry lye is commonly available as flakes, pellets, microbeads, and coarse powder (most commonly flakes). It is also available as solution, often dissolved in water. Lye is valued for its use in food preparation, soap making, biodiesel production, and household uses, such as oven cleaner and drain opener.
Food uses
Lye is used to cure many types of food, such as lutefisk, green olives, canned mandarin oranges, hominy, lye rolls, century eggs, and pretzels. It is also used as a tenderizer in the crust of baked Cantonese moon cakes, and in lye-water "zongzi" (glutinous rice dumplings wrapped in palm leaves), in chewy southern Chinese noodles popular in Hong Kong and southern China, and in Japanese ramen. In the United States, food-grade lye must meet the requirements outlined in the Food Chemicals Codex (FCC),[2] as prescribed by the U.S. Food and Drug Administration (FDA).[3] Lower grades of lye are commonly used as drain openers and oven cleaners and should not be used for food preparation.[3] Lye is a strong alkali, producing highly basic solutions.
Safety
Both wet lye and dry lye solutions are highly caustic and will degrade organic tissue.
Hazardous reactions
Solid sodium hydroxide or solutions containing high concentrations of sodium hydroxide may cause chemical burns, permanent injury or scarring, and blindness. Lye may be harmful or fatal if swallowed.
Solvation of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables.
The combination of aluminium and sodium hydroxide results in a large production of hydrogen gas: 2Al(s) + 6NaOH(aq) → 3H2(g) + 2Na3AlO3(aq). Hydrogen gas is flammable; mixing lye (sodium hydroxide) and aluminium in a closed container is therefore dangerous. In addition to aluminium, lye (sodium hydroxide) may also react with magnesium, zinc (galvanized), tin, chromium, brass, and bronze to produce hydrogen gas and is therefore dangerous.
Lye intoxication can cause esophageal stricture.
Protection
Personal protective equipment including safety glasses, chemical-resistant gloves, and adequate ventilation are required for the safe handling of lye. When in the close proximity of lye dissolving in an open container of water, a vapor-resistant face mask is recommended.[4] Abstaining from protection can result in serious injuries.
Storage
Lye is a deliquescentsalt and has a strong affinity for moisture. Lye will deliquesce (dissolve or melt) when exposed to open air. It will absorb a relatively large amount of water from the atmosphere (air) if exposed to it. Eventually, it will absorb enough water to form a liquid solution because it will dissolve in the water it absorbs.
Hygroscopic substances are often used as desiccants to draw moisture away from water-sensitive items. Desiccants should never be placed inside a canister of lye because lye has much stronger hygroscopic properties than activated carbon and silica gel (the most common ingredients in commercial desiccant packets) and will pull and absorb the water from the desiccant packets.
Lye should be stored in air-tight plastic containers. Glass should never be used for storage as lye will slowly eat away at this material. The containers should be labeled to indicate the potential danger of the contents and stored away from children, pets, heat, and moisture.[4]
Notes
References
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Solid dry lye is commonly available as flakes, pellets, microbeads, and coarse powder (most commonly flakes). It is also available as solution, often dissolved in water. Lye is valued for its use in food preparation, soap making, biodiesel production, and household uses, such as oven cleaner and drain opener.
Food uses
Lye is used to cure many types of food, such as lutefisk, green olives, canned mandarin oranges, hominy, lye rolls, century eggs, and pretzels. It is also used as a tenderizer in the crust of baked Cantonese moon cakes, and in lye-water "zongzi" (glutinous rice dumplings wrapped in palm leaves), in chewy southern Chinese noodles popular in Hong Kong and southern China, and in Japanese ramen. In the United States, food-grade lye must meet the requirements outlined in the Food Chemicals Codex (FCC),[2] as prescribed by the U.S. Food and Drug Administration (FDA).[3] Lower grades of lye are commonly used as drain openers and oven cleaners and should not be used for food preparation.[3] Lye is a strong alkali, producing highly basic solutions.
Safety
Both wet lye and dry lye solutions are highly caustic and will degrade organic tissue.
Hazardous reactions
Solid sodium hydroxide or solutions containing high concentrations of sodium hydroxide may cause chemical burns, permanent injury or scarring, and blindness. Lye may be harmful or fatal if swallowed.
Solvation of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables.
The combination of aluminium and sodium hydroxide results in a large production of hydrogen gas: 2Al(s) + 6NaOH(aq) → 3H2(g) + 2Na3AlO3(aq). Hydrogen gas is flammable; mixing lye (sodium hydroxide) and aluminium in a closed container is therefore dangerous. In addition to aluminium, lye (sodium hydroxide) may also react with magnesium, zinc (galvanized), tin, chromium, brass, and bronze to produce hydrogen gas and is therefore dangerous.
Lye intoxication can cause esophageal stricture.
Protection
Personal protective equipment including safety glasses, chemical-resistant gloves, and adequate ventilation are required for the safe handling of lye. When in the close proximity of lye dissolving in an open container of water, a vapor-resistant face mask is recommended.[4] Abstaining from protection can result in serious injuries.
Storage
Lye is a deliquescentsalt and has a strong affinity for moisture. Lye will deliquesce (dissolve or melt) when exposed to open air. It will absorb a relatively large amount of water from the atmosphere (air) if exposed to it. Eventually, it will absorb enough water to form a liquid solution because it will dissolve in the water it absorbs.
Hygroscopic substances are often used as desiccants to draw moisture away from water-sensitive items. Desiccants should never be placed inside a canister of lye because lye has much stronger hygroscopic properties than activated carbon and silica gel (the most common ingredients in commercial desiccant packets) and will pull and absorb the water from the desiccant packets.
Lye should be stored in air-tight plastic containers. Glass should never be used for storage as lye will slowly eat away at this material. The containers should be labeled to indicate the potential danger of the contents and stored away from children, pets, heat, and moisture.[4]
Notes
- ^ McDaniel, Robert (1997).
- ^Food Chemicals Codex
- ^ abUS Food and Drug Administration
- ^ abLye Safety Precautions
References
- "Federal Food, Drug, and Cosmetic Act". US Food and Drug Administration.
- "Food Chemicals Codex". United States Pharmacopeia.
- "Lye Safety Precautions". Certified Lye.
- "NaOH MSDS".
Convince yourself of our products for your applications.
We recommend the following products for your process medium:
hose diaphragm valves
diaphragm valves