Cleaning a bathroom

Where the obvious answer is wrong

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

• How do I remove limescale from a marble shower without ruining the marble?

  Marble is also calcium carbonate. The acid cannot distinguish between carbonate deposited by hard water and carbonate that is the stone itself, so it dissolves both. The result on the stone is etching: a dull, slightly rough patch where the polished surface has been chemically removed. It is not a stain and there is nothing left on the surface to clean off.

• Can I use a limescale remover on the grout in my shower?

  Cementitious grout is alkaline based and is dissolved by acids — the tile trade states this plainly and draws the conclusion itself, that manufacturers do not advocate acids because they attack the cement in the grout. Grout is also porous, so an acidic product does not merely touch the surface. The damage is gradual and looks like wear rather than like chemical attack, which is why it is rarely attributed to the cleaner that caused it.

• How do I get hard water spots off a bathroom mirror without wrecking it?

  A mirror is not a pane of glass. It is glass with a reflective coating and a protective backing, and both are exposed at every edge. The glass industry's mirror division states that acid or alkali cleaners can attack the front surface, the edges and the backing, and names cleaners containing ammonia or vinegar specifically as ones not to use. The failure is called black edge, it starts where liquid runs into the perimeter, and it is degradation of the mirror rather than dirt on it.

• Can I use a limescale remover on my bathroom taps?

  The visible part of a modern tap is a plated, physical-vapour-deposited or powder-coated finish a few microns thick, not solid metal. The manufacturer's care sheet states that PVD finishes must not meet cleaners containing ammonia, bleach or acid, which excludes most limescale removers and a good share of bathroom sprays. Because the finish is microns thick there is no margin: material lost is coating lost, the dulling is progressive, and it cannot be polished back because there is nothing underneath to polish.

• Can I use oven cleaner on the burnt-on mess in my self-cleaning oven?

  The manufacturer prohibits it in absolute terms: no commercial oven cleaner or oven liner protective coating of any kind should be used in or around any part of the oven. The mechanism is delayed rather than immediate. RESIDUE FROM OVEN CLEANERS WILL DAMAGE THE INSIDE OF THE OVEN WHEN THE SELF-CLEAN CYCLE IS USED — so the harm happens later, at pyrolytic temperature, to whatever the cleaner left behind. Someone who sprays, wipes and sees nothing wrong has not shown the practice is safe; they have postponed the test. The same guide notes that even soap left on the liner causes additional stains when the oven is heated.

• How do I get limescale off a shower screen without damaging the glass?

  The glass association's cleaning paper excludes acids from glass cleaning solutions as a class, naming hydrochloric and hydrofluoric as its examples, and warns that glass can be permanently damaged if it is infrequently or improperly cleaned. It also rules out the two things people escalate to when the acid does not work: abrasive cleaning materials, and razor blades or metal scrapers, which are excluded from routine cleaning altogether. The mechanism it gives for scratching is not the cleaner but trapped grit, so scrubbing a gritty screen is worse than leaving it.

Assessed and found wanting

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

• 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.

• Spraying hydrogen peroxide and vinegar in sequence

  Does not work

  Circulated as a two-step method precisely because neither ingredient seems like anything to worry about. Together they form peracetic acid, which irritates eyes, skin and lungs.

• Following bleach with an alcohol sanitiser

  Does not work

  Doing both to be thorough is the reasoning, and the two react. Hypochlorite with alcohols forms chloroform.

• 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.

• Granite is acid-proof, so vinegar is fine on it

  Disputed

  The stone genuinely resists kitchen acids. The worktop is not only the stone, and the trade still does not recommend acidic cleaners on it.

• Using a limescale remover on shower grout

  Does not work

  It removes the scale and dissolves the grout. Cement is alkaline, and the tile trade says acids attack it — which is what most bathroom products are.

• Mould needs bleach

  Does not work

  The environmental regulator does not recommend biocides as routine, directs detergent and water, and says the part everyone misses: killing mould is not enough, because it must also be removed.

• Vinegar for mirrors and glass

  Does not work

  The glass industry's mirror division names vinegar explicitly among the things not to use. So does it name ammonia — which is what the shop-bought alternative contains.

• 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.

• Never use an abrasive in the bathroom

  Disputed

  Right about the bath, the taps and the mirror. Wrong about the toilet and basin, where the manufacturer permits a soft abrasive outright.

• Putting a cleaning block in the cistern

  Does not work

  The manufacturer's instruction is not that it works poorly. It is that it can damage the flush valve and other working parts.

• Toothpaste as a metal polish

  Does not work

  A mild abrasive in a tube, and the tap manufacturer names it specifically among the things that must not be left on the finish.

• Scraping glass clean with a razor blade

  Does not work

  The glass industry excludes blades and metal scrapers from routine cleaning outright, and the scratches may only become visible months later at the right sun angle.

• 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.

• Cloudy dishwasher glasses can be cleaned

  Disputed

  Sometimes they can, and sometimes the cloudiness is etching — which the manufacturer states is permanent. The two look identical and have opposite answers.

• Combining bleach and hydrogen peroxide

  Does not work

  Two oxidising bleaches, so the reasoning is that together they must whiten harder. The regulator lists them as incompatible with each other.

• 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.

• Bleach ruins outdoor fabric

  Does not work

  On solution-dyed acrylic the manufacturer specifies bleach, at a stated ratio, for mildew. That permission comes from how the fibre was dyed and does not transfer to fabric that looks the same.

The records

• Toilet

  Thing to clean

  Glazed china that tolerates more than people think, surrounded by fittings that tolerate much less. The mistake is treating it as one surface.

• Bath

  Thing to clean

  Two baths made of different materials want opposite treatment, and they look almost identical once installed.

• Vitreous china

  Material or surface

  The one bathroom surface where the manufacturer permits a soft abrasive. The fittings around it are what you have to protect.

• Acrylic

  Material or surface

  A polymer, so the things that damage it are solvents and aggressive chemistry rather than acid or alkali. Almost the opposite of the china beside it.

• Vitreous enamel

  Material or surface

  Glass fused onto metal. Hard, but a scratch goes through to the iron and does not come back.

• Plated and coated tap finishes

  Material or surface

  Modern taps are a coating on a metal, microns thick. The finish decides the rules, and the rules genuinely differ between finishes on the same basin.

• Grout

  Material or surface

  Cement-based grout is porous and alkaline, and acids dissolve it. That single fact rules out most of what bathroom cleaning advice recommends for it.

• Porcelain tile

  Material or surface

  The trade defines porcelain by a number: water absorption of 0.5% or less. That number is why one tile stains and another does not.

• Limescale

  Stain or problem

  A hard, chalky calcium carbonate deposit left by hard water. Dissolved by acids, essentially untouched by detergents.

• Mould

  Stain or problem

  A living growth, not a stain. Killing it and removing the staining are two separate jobs, and neither addresses the moisture that caused it.