Oil, grease and hands

Where the obvious answer is wrong

Cases where the treatment that removes the problem is the treatment that ruins the surface it is on.

• 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.

• How do I get a grease mark off suede without ruining the nap?

  Suede is the porous lower split of the hide with nap on both sides, dyed like aniline and uncoated. The trade guide states that cleaning agents will immediately darken nude leather — there is no cautious first application, because the first application is the result. Water is not a safe alternative either: the guide specifies deionised water because hard water containing minerals may cause rings. And the guide separately prohibits alcohol, strong solvents, high-pH cleaners and dish detergent on leather generally, as incompatible with modern finishes.

• 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.

• How do I get a greasy mark off a leather sofa arm?

  The leather trade body prohibits both by name, and the reason is the finish rather than the hide. Modern leather finishes are WATER-BASED, and its banned list is built around what attacks them: any high pH cleaner, cleaners containing alcohol, strong solvents, and caustic household cleaners such as soap or dish detergent. The stated consequence is cracking or other damage to the surface. It is the same reason saddle soap and mink oil are on the list beside glass cleaner - traditional leather remedies formulated for finishes no longer used.

• 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.

• There is a greasy mark on my aniline leather sofa. Can I use a leather cleaner on it?

  Aniline leather is not finished leather. The trade body describes it as porous and DYED rather than coated, and states plainly that cleaning agents will immediately darken nude leather. There is no surface film between the cleaner and the hide, so the liquid goes in rather than sitting on top, and the darkening is absorption into the leather rather than a residue that can be wiped back off. The prohibition list this catalogue carries for finished leather is about protecting a water-based FINISH; aniline has no finish to protect, which makes it more vulnerable rather than less.

Assessed and found wanting

Widely repeated techniques in this area that the evidence does not support, or supports only in part.

• Sealing stone makes it stain-proof

  Does not work

  The stone trade's own guidance is unusually blunt about this: a sealer is a repellent, not a seal, and sealing does not make stone stain-proof.

• Natural cleaning products are safer

  Does not work

  Natural describes where something came from and predicts nothing about what it does. The UK regulator lists this belief among the myths it exists to correct.

• Mixing vinegar and bicarbonate of soda

  Does not work

  The most popular cleaning combination on the internet, and the two ingredients largely cancel each other out. Both are useful — separately.

• Vinegar as an all-purpose cleaner

  Disputed

  Genuinely excellent at one job and promoted into a universal one. The surfaces it is most often recommended for online include several it permanently damages.

• Hotter washes clean better

  Disputed

  True of the chemistry and false as advice. Temperature is one of four variables, and it is the one most fabrics constrain hardest.

• Never use soap on cast iron

  Does not work

  Among the most confidently held rules in domestic cooking, and the manufacturer contradicts it outright. The prohibition outlived the soap it was formed around.

• Steam mops are safe on sealed wood floors

  Does not work

  Steam mops are marketed for wood floors and sold in the flooring aisle. The wood flooring trade association rules them out entirely.

• Scrub a carpet stain to get it out

  Does not work

  The instinctive response to a spill, and the one the carpet trade association specifically prohibits. Scrubbing damages the carpet itself.

• Using a stone cleaner on a quartz worktop

  Does not work

  It looks like stone, it is sold as stone, and the manufacturer explicitly tells you not to use the products made for stone on it.

• Oven cleaner for a stubborn worktop mark

  Does not work

  Reaching for the strongest thing in the cupboard when a mark will not shift. On engineered quartz the manufacturer prohibits it outright.

• A stronger solution cleans better

  Does not work

  The trade body that publishes carpet stain procedures puts this in capitals: NEVER USE A STRONGER CONCENTRATION. That is a claim about damage, not about thrift.

• Steam mopping a laminate floor

  Does not work

  The European laminate producers' technical bulletin has one categorical sentence and this is it: steam cleaners are not suitable for use with any type of laminate floor.

• Washing silk at home

  Disputed

  The professional body lists five specific ways it goes wrong. It also has an obvious commercial interest in saying so, and both facts belong in the answer.

• Saddle soap and mink oil for leather

  Does not work

  The two products most associated with looking after leather are both on the trade body's prohibited list, and for the same reason: the finish changed.

• Washing-up liquid on leather

  Does not work

  The gentle-sounding option. The leather trade lists soap and dish detergent among caustic household cleaners not to use on it.

• Using oven cleaner in a self-cleaning oven

  Does not work

  The manufacturer prohibits it outright, and gives a mechanism nobody expects: the residue is what damages the oven, and it does so on the next self-clean cycle.

• All-purpose cleaner on a vinyl floor

  Does not work

  Named in the prohibition list by the flooring manufacturer, alongside steel wool and solvents — and so are the mops people use.

• Alcohol cleaners are gentle, so they are safe

  Disputed

  Its health rating is 1 and its flammability rating is 3. The hazard people underrate is the one the regulator rates highest.

• Lining hob drip pans with foil

  Does not work

  Saves cleaning, and the manufacturer forbids it with three consequences named: shock, fire or damage to the range.

• Oven cleaner on the grill pan and grid

  Disputed

  One accessory, two parts, opposite instructions. The manufacturer permits oven cleaner on the pan and prohibits it on the grid.

• Food spills on an appliance can wait until you clean

  Does not work

  For acidic spills the manufacturer says immediately, and names the consequence as discolouration rather than dirt.

• A stain method that works on cotton works on anything

  Does not work

  The wool body warns against exactly this, and gives wool a sequencing rule cotton advice does not have: solvent first, allowed to evaporate, only then water.

• Spraying disinfectant instead of cleaning

  Does not work

  Marketed as the thorough option, and it is — against organisms. On a dirty surface it can fail at both jobs at once, because soil shields the organisms it is meant to kill.

• Pouring boiling water down a drain

  Disputed

  Two confident answers circulate and neither survives contact with the evidence. The pipe manufacturer's limit is about volume and duration, not kettles — and the grease comes back anyway.

• Washing soda as a general-purpose cleaner

  Disputed

  It really is a strong alkaline degreaser, and two of its most-promoted uses are on materials that alkalis attack.

• Washing-up liquid on a bicycle

  Does not work

  Widely warned against in cycling forums, and the trade's own repair documentation specifies it: a quality dish washing soap is acceptable.

• Using baking powder instead of bicarbonate of soda

  Does not work

  Two different products with almost the same name. One of them already contains the acid that cancels it out, plus a starch that stays behind.

The records

• Engine oil

  Stain or problem

  Not simply an oil. Used engine oil carries combustion soot and metal particles, which is why it marks darker and behaves worse than the oil that went in.

• Bicycle chain grease

  Stain or problem

  A tacky lubricant loaded with road grit and metal, transferred as a sharply defined mark. The grit is what makes it more than a grease stain.

• Oil and grease on textile

  Stain or problem

  The stain where the trade guidance switches from water to solvent — and the switch brings a warning the water route does not have.

• Grease

  Stain or problem

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

• Workwear

  Thing to clean

  Clothing that meets the soils this catalogue treats as industrial. The temptation is to use the same solvent that cleaned the part — and a dryer makes that a fire warning.

• Hand cleanser

  Cleaning agent

  Built to remove what a solvent would remove, without removing the skin barrier along with it. That constraint is the entire product.

• Skin is not a surface

  Science

  The thing that dissolves a contaminant off an object dissolves the barrier that keeps your skin working. Same chemistry, entirely different consequence.

• Why oil resists water

  Science

  Water molecules attract each other so strongly that they exclude oil rather than dissolving it. Nothing about scrubbing changes that, which is what a detergent is for.

• White spirit

  Cleaning agent

  The petroleum solvent the leather and carpet trades name for oil marks. One substance under three names, and it attacks plastic, rubber and coatings.

• Acetone

  Cleaning agent

  The solvent in nail polish remover. The same fact sheet that lists it as a solvent for plastics also warns, in three words, that it attacks them.

• Two-stage degreasing

  Method

  A solvent pass followed by a detergent pass. Each finishes what the other cannot, and the trade documentation says so in one sentence.

• Cornflour or talc to draw out an oil mark

  Claim or technique

  The gentlest thing you can do to a porous surface, and two trade bodies name it as the first step rather than the last resort.