Limescale

Limescale is a film or build up of calcium salts. Since it is rough it can harbour dirt.

Tea stains contain limescale, and may be removed from ceramics and glass with acid.

Cause of Limescale

As water containing dissolved calcium salts evaporates, the calcium salts crystallise and adhere. Hard water is water containing these salts.

Prevention

Ion Exchange Water Softener

• Removes calcium ions, replacing them with sodium ions.
• Requires topups of salt
• Equipment expensive

Phosphate Dosing

• cartridge fitted to water pipe, requires periodic replacement

Regular use of lime scale removing acidic cleaner

• Helps prevents buildup

Magnetic and electromagnetic scale preventers

No evidence of them being effective has been found.

Stainless steel wool ball in kettle

• The scale deposits on the small scourer-like ball. Since the metal is thin & flexible, the scale breaks off in little pieces and is emptied down the sink with the water.

Removal

• acids
• scrapers and abrasives:
  • plastic scourers remove minimal deposits.
  • copper scourers remove more deposits, but will damage tile grout and plastics
  • aluminium scrapers remove tougher deposits than copper scourers. Not available in shops, use a small piece of very thin sheet ali a fraction of a mm thick.
  • steel scourers are hard enough to damage nearly all materials found in modern homes. May be used on steel where very light scratching is acceptable. May be used on glass, but only gently or scratching can occur.

• very heavy encrustations are removed with a needle drill, eg at municipal waterworks.

• Cotton buds are useful when acid is applied to some parts but must be kept off others.

Chemicals

Hydrochloric acid

• Strongest of all limescale removers
• Fizzes on contact with limescale
• Handle with care
• Avoid all contact with metals, grouts, mortar, concrete, cement based blocks, lime based paints, natural fibre fabrics
• Slowly dissolves eyeballs & other human parts
• Wash off skin promptly
• Darkens crazed patterning on ceramics

Sulphuric acid

• Sulphuric acid may be used for limescale removal.

Sulphamic acid

• Does not darken crazing of ceramics

Phosphoric acid

• found in some commercial limescale removing cleaners

Vinegar

• Cleans chromework such as taps

Citric acid

• Mildest of all
• A common food ingredient
• Very slow acting
• Requires heat to be effective
• Suitable for washing machines, aluminium, and unknown or mixed materials.

Safety

• Never allow acids to come into contact with bleach. People have died from doing this. If it occurs, don't wait around to figure out what happened, evacuate the area immediately. It only takes a few breaths of chlorine to kill.

• Stronger acids eat clothes, cememnt and lime based products, metal, eyes and other parts of humans. Use HCl with care.

• All acids react with copper to create toxic runoff. Wash away residues to avoid any contact with food or food preparation equipment.

Goods

Baths, plastic

Any of the acids listed will work, but the stronger ones damage chromework if contact occurs.

Shower curtains

• Any of the acids listed will work, except those requiring heat (vinegar, citric acid)
• Limescale on curtains retains water and encourages mould

Tiles

• All acids damage tile grout, so apply to tiles with care. A cotton bud can be used to get acid close to grout without getting it on the grout.
• Plastic scourers & scrapers are effective for mild scale
• Copper scrapers are more effective on tiles but will break up tile grout.

Kettle

Add citric acid, boil, let sit until cold, rinse clean.

Washing machine

Add citric acid, dont put any clothes in. Set to a 95 degree C or boil wash. When the water reaches boiling, switch the machine off and leave overnight. Switch on in the morning and let it complete its wash program.

Chromework, Taps

• plastic scourer
• heat the chrome with boiling water and apply vinegar. Rub with plastic scourer or coarse cloth.

Stainless Steel

• Tomato ketchup
• plastic scourer
• copper scourer

UPVC

• any acids

Othernyms

Hydrochloric acid brick acid, patio cleaner

Sulphamic acid Fernox DS3,

Suppliers

Hydrochloric acid Builders merchants, online BMs.

Sulphamic acid builders merchants, plumber's merchants

Citric acid chemists. Supermarkets also stock products containing citric acid at inflated prices.

Limescale removing toilet cleaners may contain any of several acids, but are invariably weak mixtures.

Other descalers

Any acid will work as a descaler. Adding salt to mild acids increases their action. Examples of other descalers include:

• tomato ketchup
• orange juice
• steel balls

NT 2006