The wettest room in the house — and the point at which cleaning stops being about surfaces, because skin is not one.
~17 min read
Every other room in the house dries between uses. The bathroom does not. It is soaked twice a day, warmed until the air holds a great deal of water, then shut behind a closed door, and everything that water carried is left on the glass and the taps as it evaporates. Nearly every difficulty in this room follows from that.
Moisture first. A hot shower puts something like 200 to 300 grams of water into the air of a small room in minutes. Warm air holds far more vapour than cool air — roughly twice as much at 25°C as at 15°C — so while the room is warm that water stays invisible. Then it meets a cold window, and comes back as liquid.
Ventilation second. The bathroom is often the one room with no opening window, and its extractor fan is the least-maintained appliance in the house. Guidance asks an intermittent bathroom fan for about 15 litres of air a second; a fan whose grille is packed with fluff moves a fraction of that, and nobody notices, because a fan doing nothing still makes a noise.
Mineral deposits third, and this is what separates bathroom cleaning from kitchen cleaning. Mains water carries dissolved calcium and magnesium — above roughly 120 milligrams of calcium carbonate per litre a supply counts as hard, and many run 200 to 350. When a droplet dries on the screen the water leaves and the minerals stay. That film is limescale, and detergent will not shift it, because detergent was never designed to. This room needs one tool the all-purpose spray did not — an acid — and one idea that arrives halfway down.
Two jobs, chemically opposite. Grease and skin oils are a detergent job; limescale and soap scum are an acid job. Doing the second with the first is why people scrub a screen for ten minutes and leave it cloudy.
A bathroom-strength spray
In a 500 mL bottle: 250 mL white vinegar, 250 mL warm water, 20 to 30 drops — 15 lemon and 10 tea tree, or 20 of Purify. Shake hard each time, since oils do not dissolve in water.
The shower screen
Spray, leave ten minutes so the acid has time to work, then squeegee and dry. For an old film, hold a vinegar-soaked kitchen towel against the glass for half an hour. Cream cleaners scratch, and scratched glass holds scale.
Taps and shower head
Unscrew the tap aerator and leave it in a cup of vinegar overnight; tie a bag of vinegar over the shower head until morning. It does more for water pressure than anything else in the room.
Grout
Bicarbonate of soda and water as a paste, an old toothbrush, ten minutes, rinse. Keep the acid spray off the lines — cement grout is partly lime, and acid erodes it. Grey grout wants resealing, once a year.
The toilet
Descaling under the rim is acid work: a tablespoon of citric acid in 250 mL of hot water, left half an hour before brushing. Bicarbonate and vinegar tipped in together make a fizz that is only the two cancelling each other out. Five drops of On Guard on the brush afterwards is scent, and should be read as scent.
The extractor fan
Switch it off at the isolator, unclip the cover and wash it, vacuum the fluff off the impeller, check the outside vent for a flap painted shut. Then run it for 15 to 20 minutes after every shower rather than switching it off with the light.
Never mix an acid with bleach
Vinegar, citric acid or a limescale remover poured onto chlorine bleach releases chlorine gas, and a bathroom is a small room with a closed door. The same goes for bleach and any ammonia-based cleaner. If bleach has been in the toilet, flush and rinse before anything acidic goes near it.
Two surfaces need the acid put down. Marble, travertine and limestone are calcium carbonate — the same mineral as limescale — so vinegar does not clean them, it etches them, and the dull patch does not polish out. A sealed acrylic bath wants no abrasive cream, since fine scratches dull the finish and then hold dirt, and no neat oil: lemon is 60 to 75% limonene and wild orange 80 to 97%, and limonene is a solvent used industrially to dissolve plastics. Dilute, rinse, keep sprays in glass — terpenes explains why.
Limescale is calcium carbonate, close to insoluble in water — which is why it sits on the glass rather than washing away — and untouched by surfactants, whose job is to lift oily soil into water. Acid works because carbonate reacts with it: a hard mineral becomes a soluble calcium salt, water and carbon dioxide, and the fizz on a scaled tap is that gas leaving. Vinegar is about 5% acetic acid; citric acid at a tablespoon to a cup of hot water is stronger and less pungent.
Black speckling along a grout line or in the silicone round the bath is a moisture problem before it is a cleaning problem. Spores are in the air of every building on earth; they do not grow because a room is dirty. They grow where a surface stays wet and there is something to feed on — soap residue, skin cells, the plasticisers in sealant. Growth in silicone is usually rooted below the surface, so cleaning lifts the colour and leaves the organism: a bead that returns within weeks needs cutting out.
What an oil does here, and what it does not
An essential oil in a bathroom spray makes a routine you will keep, and makes the room smell like something other than a wet room. That is the whole claim. An oil does not remove mould and does not prevent it. There are laboratory studies of oils against fungal cultures, but they are done on cells in a dish, which is not the same as a wet silicone bead in a real bathroom. Anyone promising a spray that keeps mould away is selling you something instead of fixing the ventilation.
What works is unglamorous and takes a minute a day. Squeegee the screen and tiles after a shower — ten seconds, and it removes most of the water that would otherwise evaporate into the room and leave its minerals on the glass. Run the fan for 15 to 20 minutes afterwards, leave both doors open once you are out, and keep the room warm enough that surfaces stay above the temperature at which water condenses. And do not dry laundry in there.
Diagram to come
A small bathroom drawn in section. Steam rises from the shower, warms and spreads along the ceiling, then arrows show it depositing as liquid on the three coldest surfaces — the window reveal, the outside-wall corner behind the towel rail, and the grout at the far end. A separate arrow shows the extractor fan removing the moist air before it reaches them. The point of the drawing is that the water does not land where it was made; it lands on whatever is coldest.
Then the textiles. A bath mat walked on wet twice a day and never hung up is the wettest object in the house. The sour note in a towel that never quite dries is not the towel — it is the by-products of bacteria living on the skin cells and sebum left in it, and a hot wash with complete drying resets it. Fabric softener works against you: it coats the fibres with a water-repellent film, so the towel absorbs less and stays damp longer. Half a cup of white vinegar in the rinse instead. Laundry, dishes and floors covers the wash.
Everything so far has been things you spray, wipe and rinse. What follows is things you make and then wear. A worktop gets two minutes and a rinse. A body butter gets eight hours, no rinse, and 1.8 square metres of you.
Contact time is the whole difference. Five drops in 500 mL of spray, wiped off a tile, is a trivial exposure. The same five drops rubbed into your forearms and left there is not, and a product applied daily is different again from one used once. That is why every recipe below states a percentage.
| Strength | Where it belongs | Per 10 mL | Per 30 mL |
|---|---|---|---|
| 0.5–1% | The face, children over two, sensitive skin | 1–2 drops | 3–6 drops |
| 1–2% | Daily body use on an adult — oil, butter, deodorant | 2–4 drops | 6–12 drops |
| 2–3% | A small area, for a short run of days, on an adult | 4–6 drops | 12–18 drops |
Those counts assume about 20 drops to the millilitre, which is what a standard reducer gives with a thin oil. A thick oil such as myrrh drops larger, so treat them as the top of the range rather than a target — a 1% body oil is not a weak one. For children under two, ask a healthcare practitioner. The Safety lesson is the authority for all of it.
Diagram to come
A vertical ladder of four rungs, strength increasing downward. Each rung carries its percentage, a row of countable drop symbols for a 30 mL bottle, and a small body silhouette with the relevant region marked — face at the top rung, the whole body in the middle two, a single small patch at the bottom. The drops must be drawn and countable rather than written as numerals, so the comparison is visual.
Patch testing is the other half of the rule. Make the product at its final strength, put a coin-sized amount on the inside of a forearm, and leave it — do not wash it, do not put anything else on it. Check at 24 hours and again at 48, because a reaction can arrive late. Test one product at a time, and test again for each new oil and separately for a child. If something appears, reach for a carrier oil rather than the tap: water spreads an oil across skin, a carrier lifts it.
The outermost layer of skin — the stratum corneum — is 15 to 20 cells thick and built like a brick wall: flattened dead cells set in a matrix of lipids. What crosses it easily is small, fat-soluble and uncharged, and most essential oil constituents are exactly that. Monoterpenes and their alcohols sit around 136 to 160 in molecular weight, under the rough ceiling of 500 above which molecules struggle to pass at all, and they dissolve into that lipid matrix rather than being repelled.
Two things follow. A carrier does not weaken an oil so much as hold it in place — neat oil on warm skin evaporates in minutes, while the same drop in a carrier stays in contact. And anything that seals the surface keeps the skin hydrated, and hydrated skin is more permeable than dry skin, so a rich anhydrous product is a more efficient route in than a light one at the same percentage. It is also why repetition matters: exposure at too high a strength, often enough, is how someone becomes sensitive to an oil they used to tolerate.
These survive contact with a real bathroom shelf. None contains water, which is deliberate — water is what grows things, and an anhydrous product needs no preservative. Add water or aloe and it needs a preservative and a fortnight in the fridge. What you can buy ready-made rather than make differs by market, since the doTERRA range is not identical across all 65 of them.
What are you making?
Each gives the base, the oils, the strength, how long it keeps, and the mistake people make first.
Write down what went into each one — a blend you cannot reproduce is the commonest small loss in this subject, and Blends exists to save them.
A carrier is 98 to 99.5% of everything you just made, so choosing it badly matters more than choosing the essential oil badly. They differ in feel, in how long they last, in how readily they sit in a pore, and in price.
Fractionated coconut
Clear, thin, odourless, liquid at any room temperature, stable for two years or more. It is coconut oil with the long-chain fats removed, which is why it stays liquid when ordinary coconut sets and why it barely oxidises. The default in a roller bottle.
Virgin coconut
Solid below about 24°C, with a distinct scent and a rich feel. Good in a butter or a balm, awkward in a roller, and usually kept off the face for its reputation for sitting in pores.
Jojoba
Not a fat but a liquid wax, close to sebum. Light, quick to sink in, stable for years rather than months. First choice for the face and for a scalp oil, and the dearest.
Sweet almond
Oleic-rich and slightly heavier, warm and slow-absorbing — good for massage. Six to twelve months. It is a tree nut, so it stays out of any product for a household that avoids them.
Shea butter
Solid, thick and protective, with an unusually high non-fat fraction — the 5 to 10% of unsaponifiables that gives it its character. It sits on the surface longer, which suits hands, feet and winter. Two years.
Argan
Light, fast-absorbing, high in vitamin E and stable at one to two years. Suits the face and the ends of hair; the price means it is usually blended.
Grapeseed
The lightest, driest feel and the shortest life — high in linoleic acid, which oxidises quickly, so three to six months and keep it cool. Good in a facial blend for oily skin.
Photograph to come
Seven small clear glass dishes in a row on a neutral surface, one carrier in each, lit so the differences are genuinely visible: the water-clarity of fractionated coconut beside the gold of argan, the green tint of grapeseed, the solid white of shea and the set coconut among the liquids. One dish tipped slightly so viscosity shows. No lettering in the photograph — the caption carries the names.
The comedogenic scale you will see quoted — 0 to 5, coconut high, argan and jojoba low — comes from a small body of patch work and is a guide rather than a law. Your own skin over a fortnight is the better test.
Carrier oils are fats — carbon chains carrying hydrogen. Where two neighbouring carbons share a double bond instead, the chain has a weak point oxygen can attack. Oleic acid, the main fat in almond and argan, has one such bond; linoleic acid, the main fat in grapeseed, has two, and each one multiplies the rate of oxidation. That is why grapeseed turns in months while jojoba lasts years. Rancid oil smells of old crayons, and does not go on skin.
Essential oils cannot go rancid, having no fats, but they oxidise in their own way and it matters more. Limonene — 60 to 75% of lemon, 80 to 97% of wild orange — forms oxides on contact with air that are likelier to provoke a skin reaction than the fresh oil, and the same holds for the terpenes in tea tree. Hence small bottles, tight lids, cool dark storage and refrigerated citrus.
Cold-pressed citrus oils carry furanocoumarins, compounds pressed out of the peel along with everything else. They absorb ultraviolet light, and once energised they react with skin cells in a way the oil alone never would. The result is a phototoxic reaction — darkening or burning in the shape the oil was applied in, hours after the sun. So the rule is unconditional: after applying an expressed citrus oil to skin, keep that skin out of direct sunlight and off sunbeds for 12 hours.
The rest of the limits are short and they do not move. Nothing in or near the eyes, nothing in the inner ear. Nothing neat — dilution is how these products are used, and it generally makes them work better rather than worse. Broken skin absorbs unpredictably and stings, so leave it alone. The hot oils — oregano, cinnamon bark, cassia, clove and thyme — belong at 0.5% or less and have no place in a whole-body leave-on product. Peppermint stays away from the face and neck of a child under six, along with eucalyptus and rosemary. And oils never go into a bath alone: with nothing to disperse them they float as neat droplets and meet the skin at full strength, so stir them into a tablespoon of carrier first. Skin and hair goes further.
Keep oils away from eyes and inner ears, and out of reach of children. If you are pregnant, nursing, under medical care or taking medication, speak to your healthcare practitioner before use. Nothing here is intended to diagnose, treat, cure or prevent any disease.
Oil pulling is an old practice from Ayurvedic tradition: a tablespoon of coconut or sesame oil swished in the mouth for ten to twenty minutes and then spat out. It is harmless if you do two things — spit it into a bin rather than the sink, because coconut oil sets solid below about 24°C, and do not swallow it. It is a practice you may enjoy, not one that replaces the brush.
doTERRA makes an On Guard toothpaste and an On Guard mouth rinse in the markets where they are registered, and both are worth trying if you would rather not make a dental product yourself. For anything that goes in the mouth the label is the authority: use an oil that way only if the label on your bottle says it is for internal use, since labelling differs across markets. One drop of peppermint is roughly equivalent to 28 cups of peppermint tea.
None of this replaces brushing, flossing or seeing a dentist, and it is not meant to. Whether a toothpaste suits you, including the question of fluoride, is a conversation with your dentist. This is different from professional dental care and does not stand in for it.
Lesson 5 of 7 · Clean Home + DIYs