Dishwasher spray arm
The rotating arms that spray the wash water. Food caught in them is one of the first things a manufacturer checks when a dishwasher smells.
Precautions
- Check the manufacturer's instructions
Start here
What this is, what tends to go wrong with it, and what to do about it.
Made from
What tends to go wrong
A hard, chalky calcium carbonate deposit left by hard water. Dissolved by acids, essentially untouched by detergents.
Why it is difficult: Water hardness, Crystallisation, Adhesion and cohesion
Fats and oils, which water alone cannot lift. Removed by surfactants, by heat, by solvents, or by alkalis that convert the fat into soap.
Why it is difficult: Why oil resists water, Emulsification
- Dustvia its material
Mostly textile fibres and skin, held by static as much as by gravity — which is why a dry cloth on a plastic surface makes it worse.
Why it is difficult: Static and dust, Mechanical action and abrasion, Why different surfaces get different dirt, Surface roughness
A concentrated water-soluble dye with nothing else in it. Nothing has to be emulsified or dissolved — the only question is whether the surface has taken the colour up.
Why it is difficult: Capillary absorption, Dye migration and colour bleeding
A sticky, yellow-brown tar film deposited everywhere at once. It is the reason a room smells after everything visible has been cleaned.
Why it is difficult: Adsorption of odour molecules, Solubility and polarity
Coloured by turmeric in most prepared mustards, and curcumin is a pH indicator — which is why an alkaline cleaner turns a yellow mark red.
Why it is difficult: pH indicators in stains, Fat-soluble pigments, Photodegradation, Pigment retention
The commonest cleaning problem that is not dirt. The tackiness is the plastic's own additive arriving at the surface, which is why wiping it off works for a week.
Why it is difficult: Plasticizer migration, Damage versus soiling
The science behind this: Solvent crazing, Static and dust, Solvents and polymers, Plasticizer migration
Part of Dishwasher.
In detail
A dishwasher has no scrubbing action: the spray arms throw the wash water at the load, and detergent and heat do the rest. One manufacturer names food debris trapped in the spray arms, alongside the filter and the bottom of the tub, among the causes of a dishwasher that smells, which makes the arms part of routine checking rather than a repair. Its maintenance advice for odour is a hot empty cycle with a dishwasher cleaner or white vinegar about once a month, and wiping the door seals and interior with a damp cloth and mild detergent. Whether the arms come out, and how, depends on the model, so the machine's own manual decides that.
Related
- Dishwasher spray arm is made from Household plastics
- Dishwasher spray arm is commonly affected by Limescale
- Dishwasher spray arm is commonly affected by Grease
Sources for this page
Sources
Removing Odors in your Dishwasher
Whirlpool Corporation · Manufacturer documentation
Relied on for: That food debris trapped in the spray arms, the filter or the bottom of the machine causes odour, and that a hot empty maintenance cycle with a dishwasher cleaner or white vinegar is run about once a month. (states this directly)