Coffee machine
An appliance that heats hard water continuously, and where one maker's own descaling routine begins by taking out the filter that exists to prevent scale.
Precautions
- Check the manufacturer's instructions
- Rinse thoroughly afterwards
- Do not apply to a hot surface
- Never mix with other cleaning products
Start here
What this is, what tends to go wrong with it, and what to do about it.
Made from
Which part are you cleaning?
These parts take different answers. Cleaning one the way you clean another is a common way to damage this.
- Coffee machine water filter
The part that exists to prevent scale, and the manufacturer's descaling procedure begins by taking it out — a step almost no consumer coverage mentions.
Household plastics
Things not to use here
- Coffee machine drip tray
Warm, wet and full of spent organic matter between emptyings. It is the part of a coffee machine most likely to smell, and the least likely to be descaled.
Household plastics, Stainless steel
Things not to use here
- Milk frother
A protein circuit inside a machine otherwise designed around minerals. It needs cleaning on a different schedule and for entirely different reasons.
Household plastics, Stainless steel, Natural rubber
Things not to use here
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
A living growth, not a stain. Killing it and removing the staining are two separate jobs, and neither addresses the moisture that caused it.
Why it is difficult: Porous and non-porous surfaces, Moisture control and recurrence, Cleaning, sanitising and disinfecting, Organic load, Surface roughness
- 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
- Fingerprintsvia its material
Skin oils transferred by touch. A greasy soil rather than a dirty one, which is why water alone does not shift them and why they return immediately.
Why it is difficult: Surfactancy
- Water marksvia its material
What hard water leaves behind when it evaporates instead of being wiped away. A mineral film, not dirt, and the fix is at the drying stage.
Why it is difficult: Water hardness, Evaporative deposition
- Rustvia its material
Hydrated iron oxide from corroding iron or steel. Distinguish a surface deposit, which cleans off, from active corrosion of the item itself, which does not.
Why it is difficult: Corrosion and passivation, Why old stains are harder, Adhesion and cohesion
- Burnt-on food and carbon depositsvia its material
Food heated until it carbonised and bonded to the surface. Time and softening do the work; scouring powder does the damage.
Why it is difficult: Contact time, Carbonisation, Adhesion and cohesion, Why old stains are harder
- Greasevia its material
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
- Heat tintvia its material
The rainbow or brown bloom on stainless steel that has been heated. Not a deposit and not dirt: the metal's own surface oxide, thickened by heat.
- Mildewvia its component
The flat, powdery surface growth that appears on damp fabric, grout and shower curtains — and the carpet trade's procedure for it names no bleach at all.
Why it is difficult: Moisture control and recurrence, Porous and non-porous surfaces, Organic load
- Coffee oil residue· no established method
The film inside a brewer that makes good beans taste stale. It is an oxidised oil rather than a stain, and descaling does not touch it.
Why it is difficult: Why old stains are harder, Why oil resists water
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
Protein and fat in water, and the reason a dried milk spill smells long after the mark has gone is that the protein is still there.
Why it is difficult: Protein denaturation, Adsorption of odour molecules, Heat-set stains, Penetration into fibres
The science behind this: Water hardness, Solvent crazing, Static and dust, Solvents and polymers, Plasticizer migration, Corrosion and passivation
In detail
A bean-to-cup machine is a pressurised water circuit with a heater in it, which makes limescale its defining maintenance problem — the manufacturer's own guidance calls descaling the most important maintenance procedure. The manufacturer's own guidance gives three things the consumer coverage of it leaves out. The FILTER COMES OUT FIRST: the water tank is removed, the lid lifted, and the water softener filter taken out if fitted before the descaler goes in, then refitted during the rinsing. Descaling through the softener defeats both. The RINSING IS THE PART THAT GETS SKIPPED: two full rinse cycles follow the descale, each with the tank emptied, rinsed under running water and refilled to maximum — and if the tank was not filled to maximum, the machine prompts for a THIRD rinse specifically to ensure the descaler solution has been completely eliminated from the internal circuits. The manufacturer also carries its own scalding warning: hot water containing acid comes out of the spouts during the cycle. On frequency it declines to give an interval and points at the machine's water hardness SETTING instead — set it to match the water in use and the machine decides when.
Why
- Coffee machine is explained by Water hardness
Related
- Coffee machine has the component Coffee machine water filter
- Coffee machine has the component Coffee machine drip tray
- Coffee machine has the component Milk frother
- Coffee machine is made from Household plastics
- Coffee machine is made from Stainless steel
- Coffee machine is made from Natural rubber
- Coffee machine is commonly affected by Limescale
- Coffee machine is commonly affected by Coffee oil residue
- Coffee machine is commonly affected by Mould
Aftercare and prevention
- Neutral cleaning requires the aftercare Coffee machine
Hacks and claims involving this
- Descaling a coffee machine with vinegar Unresolved
Sources for this page
Sources
Guide: Descaling — De'Longhi Coffee Machines Help Center
De'Longhi · Manufacturer documentation
Relied on for: That descaling is the most important maintenance procedure, that the water softener filter is removed before descaling and refitted during rinsing, that hot water containing acid flows from the spouts, and that a third rinse is prompted to ensure the descaler is completely eliminated from the internal circuits. (states this directly)
Descale light is flashing frequently — De'Longhi Coffee Machines Help Center
De'Longhi · Manufacturer documentation
Relied on for: That frequent descaling prompts are attributed to the machine's water hardness setting, and that the instruction is to match the setting to the water in use. (states this directly)