Potassium hydroxide
The other caustic alkali, and the one a regulator puts a number to: liquid drain cleaners contain a quarter to a third of it by weight.
What not to do
Potassium hydroxide is unsafe on Aluminium
Unsafe
Do not do this. The risk is established, and it is described below.
The reaction gives off hydrogen, which is flammable. This is a hazard as well as a damage warning.
Precautions
- Ventilate the area
- Wear gloves
- Wear eye protection
Why we say this
Strongly supported
A regulator naming the metal and the gas. The damage is the metal being consumed, so it cannot be polished out, and the hydrogen is a separate hazard in an enclosed space.
Sources
Right to Know Hazardous Substance Fact Sheet: Potassium Hydroxide (RTK 1571)
New Jersey Department of Health, 2010 · Government or regulator
Relied on for: That potassium hydroxide is corrosive in moist air to aluminium, zinc, tin and lead and forms flammable and explosive hydrogen gas. (states this directly)
Verification: a person has read the passage relied on.
Read on — The 'Description and Use' paragraph and the 'Handling and Storage' reactivity list. Supports the claim as stated. Completes the caustic pair, and the aluminium statement is the evidential basis for warning against caustic oven products on aluminium bakeware and trim, which had rested on the sodium hydroxide record alone.
Last reviewed by a person on .
Potassium hydroxide is unsafe on Galvanised steel
Unsafe
Do not do this. The risk is established, and it is described below.
Precautions
- Wear gloves
- Wear eye protection
Why we say this
Strongly supported
Galvanising is a zinc coating, and consuming the zinc removes the protection rather than cleaning the steel.
Sources
Right to Know Hazardous Substance Fact Sheet: Potassium Hydroxide (RTK 1571)
New Jersey Department of Health, 2010 · Government or regulator
Relied on for: That potassium hydroxide is corrosive in moist air to metals including zinc. (states this directly)
Verification: a person has read the passage relied on.
Read on — The 'Description and Use' paragraph and the 'Handling and Storage' reactivity list. Supports the claim as stated. Completes the caustic pair, and the aluminium statement is the evidential basis for warning against caustic oven products on aluminium bakeware and trim, which had rested on the sodium hydroxide record alone.
Last reviewed by a person on .
Potassium hydroxide is unsafe on Natural rubber
Unsafe
Do not do this. The risk is established, and it is described below.
Why we say this
Supported
The regulator's own qualifier — some forms — is preserved rather than removed, which is why this sits at supported rather than strongly supported.
Sources
Right to Know Hazardous Substance Fact Sheet: Potassium Hydroxide (RTK 1571)
New Jersey Department of Health, 2010 · Government or regulator
Relied on for: That potassium hydroxide attacks some forms of plastics, rubber and coatings. (states this directly)
Verification: a person has read the passage relied on.
Read on — The 'Description and Use' paragraph and the 'Handling and Storage' reactivity list. Supports the claim as stated. Completes the caustic pair, and the aluminium statement is the evidential basis for warning against caustic oven products on aluminium bakeware and trim, which had rested on the sodium hydroxide record alone.
Last reviewed by a person on .
Precautions
- Never mix with other cleaning products
- Wear gloves
- Wear eye protection
- Ventilate the area
- Keep away from children and pets
- Rinse thoroughly afterwards
In detail
Potassium hydroxide is sodium hydroxide's twin, and domestic products are formulated on whichever is cheaper or more soluble for the job. The New Jersey fact sheet does something its sodium counterpart does not — it says how much is in the bottle: liquid drain cleaners contain 25 to 36 per cent potassium hydroxide. That figure is worth having, because it turns a category statement about caustics into something a reader can weigh against what the same sheet says happens on contact, which is that this is a highly corrosive chemical whose contact can severely irritate and burn skin and eyes leading to eye damage. On surfaces the decisive fact is a metals one. Potassium hydroxide is corrosive in moist air to aluminium, zinc, tin and lead, forming flammable and explosive hydrogen gas as it goes. Aluminium is the one that matters domestically, because it turns up as bakeware, pan bases, extractor trim and window frames, and a caustic oven or drain product that touches any of them does visible, permanent damage. It also attacks some plastics, rubbers and coatings, and reacts violently with strong acids.
Properties
- Chemical name
- Potassium hydroxide
- pH
- Strongly alkaline
What works
Potassium hydroxide is effective against Grease Supported
It converts fat into soap rather than lifting it, which is why it works where a detergent has already failed.
Why
- Potassium hydroxide is explained by pH in cleaning
- Potassium hydroxide is explained by Saponification
- Potassium hydroxide is explained by Alkali attack on light metals
Sources for this page
Sources
Right to Know Hazardous Substance Fact Sheet: Potassium Hydroxide (RTK 1571)
New Jersey Department of Health, 2010 · Government or regulator
Relied on for: That liquid drain cleaners contain 25 to 36 per cent potassium hydroxide, that it is highly corrosive, and that it is corrosive in moist air to aluminium, zinc, tin and lead, forming hydrogen gas. (states this directly)
Verification: a person has read the passage relied on.
Read on — The 'Description and Use' paragraph and the 'Handling and Storage' reactivity list. Supports the claim as stated. Completes the caustic pair, and the aluminium statement is the evidential basis for warning against caustic oven products on aluminium bakeware and trim, which had rested on the sodium hydroxide record alone.
Last reviewed by a person on .