What is Rust?
The scientific name for rust is ‘iron oxide’ and it is a compound formed when iron combines with oxygen in the presence of water, through the process of oxidation, otherwise known as ‘rusting’ or ‘corrosion’. Iron combines so easily with oxygen that pure iron is very rarely found in nature and the chemical compounds in liquids like acid rain and sea water speed up this corrosion process, thus iron is more prone to rusting in areas exposed to these liquids. Similarly heat will increase rusting as it speeds up chemical reactions. Unfortunately, iron oxide is a larger molecule than iron and so when rust forms, it essentially “puffs up” – this causes cracks and voids, which then exposes more iron metal to the environment and encourages more rusting, ie. a vicious circle.
Rust Stains
Rust can leave a very unsightly reddish-brown stain which can be difficult to remove. If you find rust stains on clothing, first of all make sure that you do not put the garments in the dryer or iron them before treating the stains. Heat may set the stains permanently and make them impossible to remove. Also, never use chlorine bleach as this will set the stain as well.
One of the best solutions for rust stains on clothing is lemon juice (citric acid) or the stronger white vinegar (acetic acid). Both of these are mild acids which will help dissolve the iron oxide compound. Place some absorbent white paper towels beneath the stain to act as a blotter, then cut a lemon in half and soak the stain with fresh lemon juice (alternatively, bottled lemon juice will also work). Leave the garment (with the paper towel blotter still beneath the stain) out in the sun to dry and the rust stain should gradually disappear. Wash according to the usual instructions.
You can also launder the stained clothing with commercial rust removers – these will also contain acids, usually oxalic or hydrofluoric acid – which will combine with the iron and loosen it from the fabric, then hold it in suspension in the water. However, these are often only designed for use on white or colourfast fabrics Be very careful, also, as these acids are highly poisonous.
In some cases, the rust staining (especially if it appears after a wash) actually comes from the high iron content in the water or is due to a rusting washing machine tub. For the former problem, a water conditioner or iron filter may be a worthwhile investment while for the latter, unfortunately, the only solution is to replace the washing machine tub, as otherwise it will eventually spring a leak.
For rust on non-porous materials, such as around drains and faucets and kitchen counters, you can also use lemon juice or white vinegar: dampen a sponge with either and then rub the stain vigorously. If the stain is stubborn or if the stain is on a porous surface, you may have to resort to using oxalic acid, which can be purchased as a powder from a hardware or marine-supply store. Remember that oxalic acid is highly toxic if ingested – it works on rust by forming a water-soluble complex (called a chelate) around each iron ion and it will react likewise with the iron in your blood, making it as poisonous as cyanide. Store it safely and keep it out of reach of children and pets; make sure you protect yourself before use by wearing gloves, eye protection and long sleeves as it is also a skin and eye irritant. To make sure you have removed all traces of toxic solution, spray the area lightly with an alkaline, all-purpose household cleaner to neutralise the acid, then rinse again.
If the stain is really stubborn, then you may want to try using a block of pumice (volcanic roack) to scrub at the stain – being a mild abrasive, the pumice will abrade the surface and remove the rust deposits. However, proceed with great care and with as little abrading as possible – once the surface is scratched or worn down, it will attract stains more easily. Remember, never use chlorine bleach as this sets the iron stain.
For rust stains on carpet, try lemon juice diluted with water first – otherwise, it may be best to use commercial carpet cleaning products or even call in the professionals.