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Grease

Fats and oils, which water alone cannot lift. Removed by surfactants, by heat, by solvents, or by alkalis that convert the fat into soap.

In detail

Grease resists water for a simple reason: fats and oils are non-polar and water is polar, so water cannot wet or carry them away. Three routes get round this. Surfactants — the active ingredients in washing-up liquid and most cleaners — have a water-attracting end and an oil-attracting end, so they surround oil droplets and hold them suspended in water long enough to be rinsed. Heat helps by lowering the viscosity of the fat so it can be moved at all, which is why hot water genuinely works better here and not merely psychologically. Strong alkalis take a different route: they react with fats to produce soap, which then dissolves. That saponification route is what makes caustic oven cleaners effective on baked-on fat, and it is also why they attack aluminium, skin and painted surfaces, all of which are vulnerable to the same chemistry.

What works

Aftercare and prevention

  • Dry soil removal helps prevent Grease

    In the drain context this is the whole answer: scrape and bin the fat rather than rinse it, and there is nothing in the pipe to clear later.

Hacks and claims involving this

When the obvious answer is wrong

Can I use oven cleaner or a strong degreaser on aluminium?

Aluminium is amphoteric — attacked by strong bases as well as by strong acids. The alkali dissolves the protective oxide film and then the metal beneath, leaving a dull grey or blackened surface that is not a deposit and cannot be cleaned off. There is a second consequence that is a safety matter rather than a cosmetic one: a US state hazardous substance fact sheet records that sodium hydroxide reacts with metals including aluminium to form flammable and explosive hydrogen gas, which is not what anybody expects from cleaning an oven tray in a confined space.

A different kind of treatment works: Take the contact-time route instead of the chemical-strength route. Soaking in hot water with an ordinary detergent softens polymerised soil given long enough, and repeating a mild treatment is the trade's stated sequence for burnt-on deposits precisely because the aggressive alternatives damage surfaces. Where the item is unquestionably steel rather than aluminium the caustic route is available, so the first thing worth establishing is which metal you have — aluminium trays and steel trays look similar and behave completely differently. If a caustic product has already been used, ventilate and do not enclose the item while it is reacting.

What should I use on a greasy mark on a wool jumper?

Wool is a protein fibre, and the mechanism that converts fat to soap also hydrolyses protein. A strong alkali therefore attacks the garment on the same chemistry it uses on the stain, and the damage is to the fibre rather than to its appearance — it is not a mark that can be cleaned off afterwards. The wool body approaches the same problem from the other end, warning that methods primarily aimed at garments made from cotton or synthetic fibres are not all suitable for wool, and specifying a dilute wool detergent in TEPID water rather than anything stronger or hotter.

A different kind of treatment works: Change the mechanism from saponification to dissolution, and respect the order. The wool body's instruction for oily or greasy stains is that they are best treated with SOLVENTS FIRST, and that the solvent MUST BE ALLOWED TO EVAPORATE before any water-based treatment is subsequently carried out. That waiting step is the part most likely to be skipped and it is stated explicitly. The water-based stage that follows is a dilute solution of an approved wool detergent in tepid water — dilute rather than strong, tepid rather than hot. Technique carries the rest: scoop or blot the excess quickly with white tissue or an absorbent towel, work from the edge of the mark towards the centre, and do not rub. Where the mark survives that, the honest next step is professional cleaning rather than a stronger alkali.

How do I get grease off a vinyl seat without leaving a mark on it?

The coated-fabric trade body classifies vinyl, polyurethane and silicone coated fabrics as SOFT-SURFACE materials despite their being smooth and non-permeable, and states that hard-surface cleaners, sanitizers and disinfectants are not intended for soft surfaces and could damage them. It then names hand sanitisers among the substances that STAIN coated fabric. So the alcohol wipe that removes the grease is on the list of things that mark the seat, and the mark it leaves is not a soil sitting on the coating that can be wiped off again.

A different kind of treatment works: Take the soil off first with a soft-surface product rather than a hard-surface one, and treat cleaning and disinfecting as two operations rather than one. The trade body is explicit that they are not the same: a soil-removal product may not disinfect and a disinfectant may not remove soil, and the surface should be clean of soil BEFORE anything is sanitised or disinfected. Then rinse, which is the step this source says almost nobody performs — it observes that technicians typically do not rinse coated fabric, so product residue is the normal state of the surface rather than the exception. A residue film is what makes a cleaned vinyl seat feel tacky and pick up the next mark faster. None of this applies to ordinary fabric upholstery, which is a different material with different guidance.

Sources for this page

Sources

  1. Kirk-Othmer Encyclopedia of Chemical Technology

    John Wiley & Sons · Reference work

    Relied on for: That surfactants act by reducing interfacial tension and emulsifying oils, and that alkaline hydrolysis of fats produces soaps.

    Verification: the work exists and is described correctly. Nobody has yet read the specific passage.

What CleaningHQ cannot answer yet

These are recorded questions about this subject that we have not yet researched to a standard we would publish.

  • Remove baked-on grease from an oven cavity
  • Remove oily soil from textiles
  • Remove polymerised grease from painted or laminated cupboard doors
  • Remove set oily staining from textiles
  • Compare surfactant and alkaline routes to grease removal
  • Diagnose odour in a dishwasher
  • Assess low-hazard routes to oven cleaning
  • Remove oil from a workshop timber surface
  • Select a degreasing agent for drivetrain components
  • Clean aluminium alloy road wheels
  • Address film and smearing on vehicle glass
  • Remove accumulated oils and residue from a hairbrush
  • Remove coffee oils and staining from a press pot
  • Remove pigmented oily soil from cotton
  • Cleaning interval for an extractor filter
  • Clean the filter of a domestic dishwasher
  • Remove fatty soap residue from bathroom surfaces
  • Clean a ventilation fan and its housing
  • Clean the high-contact areas of upholstery
  • Whether diluted acetic acid removes cooked-on grease from an air fryer
  • Reach soil in the cavity between an oven door's glass panes

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