Material
Concrete
Alkaline cement that is etched by acid and, unsealed, absorbs almost instantly. Whether it is sealed decides which problem you have.
- SurfacePorous
- WashingSpot only
- Colour run riskLow
- Reviewed7 September 2026
What concrete can and cannot take
- Heat Use with care
- Water and soaking Use with care
- Acids, including vinegar Avoid
- Strong alkalis Use with care
- Solvents Use with care
- Chlorine bleach Use with care
- Abrasives Avoid
Always test on a hidden area first and let it dry before you treat the visible mark.
General rules for concrete
Find out whether the concrete is sealed before deciding anything. A sealed polished floor behaves like a hard plastic surface; bare concrete behaves like a very absorbent stone.
On sealed concrete, a milk spill wipes off and the risk is to the sealer from strong cleaners rather than to the concrete.
On bare or worn concrete, the spill is in the slab within seconds, and a poultice is the only route out. Acid is excluded either way, because it etches cement.
Check the label
Concrete is cement, sand and aggregate, and it is alkaline. Acid attacks the cement paste directly, etching the surface and exposing the aggregate. Most domestic concrete floors and worktops are sealed, and the sealer rather than the concrete is usually what a spill lands on.
Stains on concrete
- Baby sick Check whether the concrete is sealed by putting a drop of water on it: if it beads, it is sealed and a milk s...
- Blood Blot first, then use cold water and a tiny amount of compatible detergent. Work from the edge, rinse or blot...
- Body oil Lift free oil from concrete, then clean a small area with a maker-approved mild detergent solution and a soft...
- Breast milk Blot the spill, identify the finish and use a controlled cold clean only where permitted. Where the maker per...
- Bronzer Lift loose bronzer from concrete before it is rubbed in. Blot cream bronzer, follow the material or care labe...
- Coffee Wipe coffee off concrete promptly with a soft cloth. Identify stone, sealer and adjacent grout before choosin...
- Concealer Lift the concealer from Concrete, clean with neutral stone cleaner or very dilute washing-up liquid, rinse an...
- Cooking grease Blot cooking grease from Concrete, absorb surface oil, wash gently with mild detergent and judge when dry. A...
- Deodorant Lift loose deodorant from concrete with a dry white cloth, then wipe the remaining film with cool water and o...
- Hair dye Blot hair dye from Concrete, test the mildest compatible cool detergent route, clean inwards, remove residue...
- Lipstick Lift lipstick from Concrete, clean with neutral stone cleaner or very dilute washing-up liquid, rinse and dry...
- Motor oil Blot motor oil from Concrete, absorb surface oil, wash gently with mild detergent and judge when dry. A remai...
- Nail polish Lift free polish gently if the face permits contact. A maker-approved mild damp wipe can clear loose residue,...
- Period blood Lift any tissue with a spoon edge, then blot. Use cold water and a tiny amount of compatible detergent for th...
- Pet urine Blot until nearly dry, then use only the cool-water quantity concrete can tolerate. Use a labelled pet urine...
- Tomato sauce Lift tomato sauce from Concrete, then wipe or blot inwards with a tested cool detergent solution. Remove resi...
Concrete is cement paste binding sand and aggregate, and it is chemically alkaline.
Acid attacks the binder
Not the aggregate. That means acid etching on concrete shows as a rough patch with the stones standing proud, which is both visible and permanent.
Sealing changes the material
A sealed polished concrete floor is effectively non porous and wipes clean. Bare concrete is one of the most absorbent surfaces in a house.
It is alkaline itself
So alkaline cleaners are relatively safe on it, which is the opposite of most stone. Strong ones can still damage a sealer.
Old stains sit deep
Concrete draws liquid several millimetres in, so a poultice on concrete needs longer and more repeats than on a dense stone.
Sources
What we checked and when. Where a manufacturer instruction disagrees with anything here, follow the manufacturer.
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Terrazzo maintenance, National Terrazzo and Mosaic Association
trade body
Terrazzo trade body guidance to clean with a neutral product between pH 7 and 10, that harmful acids and alkalis damage terrazzo, that all purpose cleaners and soaps containing water soluble or crystallising salts should be avoided, that sand based compounds abrade the floor, that solvent based sealers discolour with age, and that spills need immediate cleanup because terrazzo stains.
Checked 7 September 2026
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Guide to cleaning marble stains with poultices, Olson Marble and Stone Care
specialist
Stone restoration specialist describing a poultice as an absorbent powder mixed with a cleaning agent, bicarbonate of soda with hydrogen peroxide for an organic stain, spread about a quarter of an inch thick, covered with plastic wrap taped down and left for 24 to 48 hours, that stubborn stains need more than one application, and that a stone that is deeply etched or discoloured beyond surface penetration needs professional restoration rather than a poultice.
Checked 7 September 2026
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Cleaning grout, Tile Council of North America
trade body
Tile trade body guidance that grout manufacturers do not advocate the use of acids because acids attack the cement in the grout, that grout is alkaline based and is dissolved by acids, that mildly alkaline cleaners are preferred over acidic ones, that oil and wax based cleaners leave a film that attracts dirt, that alkaline cleaner not properly rinsed leaves a sticky residue, and that cementitious grout should be sealed to prevent staining.
Checked 7 September 2026