Does sealed concrete stain at all?

Yes, but slowly and shallowly. A sealer buys you time rather than immunity. Almost everything comes off if you deal with it the same day. Almost nothing comes off cleanly if you leave it a week.

What is the worst thing to spill?

Acid. Lemon juice, vinegar and some descalers etch the surface, which is physical damage rather than a stain. Oil is second, because it moves downward into the material instead of sitting on top.

Can I use bleach on concrete?

Not on a sealed surface. Bleach attacks the sealer and leaves a lighter patch where the sealer is thinner. It also does not do much to the stain, which is usually below the sealer, not on it.

A paste that sits on a stain, draws it upward as it dries and takes it with it. Baking soda or diatomaceous earth mixed with a suitable liquid, spread thick, covered, and left overnight. It is the only method that reaches a stain that has gone into the material.

Material care · 4 min read

Removing Stains From Concrete Furniture

Wine, oil, coffee and citrus each behave differently on sealed concrete. What lifts, what fades and what stays.

Concrete is porous. A sealer narrows the pores and slows everything down, which is why a sealed bench survives a dinner and an unsealed one records it. Understanding where a particular stain sits is the whole job, because the method depends entirely on whether the mark is on the sealer, under it, or an actual hole in the surface.

Three kinds of mark

On the sealer. Dried food, drink residue, scuffs from a plate. Wipes off with warm water.
Under the sealer. Oil, wine and coffee that found a thin spot or an edge and soaked in. Needs drawing out.
Etching. Acid has dissolved a shallow layer of the cement paste. There is nothing to remove. The surface itself has changed shape and reflects light differently.

Most people treat all three the same way, scrub harder each time, and end up with a worn patch of sealer on top of the original problem.

First, always

Blot, do not wipe. Wiping spreads a spill across more surface and presses it in. Lay a paper towel on, press, lift, repeat with a fresh one. Then clean with warm water and a drop of pH-neutral washing-up liquid, and dry.

On a sealed surface dealt with the same day, that is usually the end of it. The Concrete Bench is sealed against exactly this, which is why it works indoors at a table and outdoors on a terrace.

By substance

Red wine

Pigment, and it moves fast on anything porous. Blot immediately. If a pink shadow remains after cleaning, make a poultice with baking soda and a little hydrogen peroxide, spread it 5 mm thick over the mark, cover with cling film, tape the edges and leave overnight. Remove, rinse, dry. Repeat once if it faded but did not go.

Cooking oil and grease

The hardest, because oil travels down rather than sitting. It leaves a dark patch with a soft edge. A water-based cleaner will not reach it. Use a poultice with an absorbent powder and a solvent suited to oil, such as acetone, keeping it strictly on the concrete and off any adjacent steel or wood. Expect two or three attempts on an old stain, and expect it to lighten rather than vanish.

Coffee and tea

Tannin. Behaves like wine but fades more readily. The baking soda and peroxide poultice is usually enough. Do not use a strong alkaline cleaner, which attacks the sealer and leaves you with two problems.

Citrus, vinegar and descaler

These etch. If a lemon slice sat on the surface overnight you will see a dull, slightly rough patch rather than a coloured one. No cleaner fixes this, because nothing was deposited. The surface was dissolved. The options are to live with it, because it flattens visually as the piece ages, or to have the top resealed, which makes the sheen even again without restoring the lost texture.

Rust marks

From a tin, a bike part or a steel object left wet on the surface. Iron staining needs an oxalic acid product made for stone. That is itself an acid, so it must be used quickly, rinsed thoroughly and followed by resealing the area.

What not to do

No scouring. A pad or cream cleaner removes sealer, not stain. You end up with a matte patch that absorbs the next spill faster.
No bleach. Attacks the sealer, rarely reaches the stain.
No pressure washer on a cast piece, even outdoors.
No acid unless you are specifically treating rust and intend to reseal afterwards.

Reseal after a serious removal

Any method that uses solvent, peroxide or acid will thin the sealer in that spot. If you do not reseal, that area is now the most absorbent part of the piece and the next spill lands exactly there. Resealing is explained in sealing cast concrete furniture, and if the piece has a matte finish, read maintaining a matte sealer first, because a patch repair on matte shows more than on gloss.

Reality check

Same day: almost everything comes out. Next week: almost nothing comes out cleanly.
Blot. Do not wipe.
Oil needs a poultice, not a cleaner.
Etching is damage, not dirt. No product removes it.
Any aggressive removal costs you sealer. Put it back.
Concrete that has been used for ten years will show it, and most people end up preferring that to a surface that looks untouched.

Common questions

Does sealed concrete stain at all?: Yes, but slowly and shallowly. A sealer buys you time rather than immunity. Almost everything comes off if you deal with it the same day. Almost nothing comes off cleanly if you leave it a week.
What is the worst thing to spill?: Acid. Lemon juice, vinegar and some descalers etch the surface, which is physical damage rather than a stain. Oil is second, because it moves downward into the material instead of sitting on top.
Can I use bleach on concrete?: Not on a sealed surface. Bleach attacks the sealer and leaves a lighter patch where the sealer is thinner. It also does not do much to the stain, which is usually below the sealer, not on it.
What is a poultice?: A paste that sits on a stain, draws it upward as it dries and takes it with it. Baking soda or diatomaceous earth mixed with a suitable liquid, spread thick, covered, and left overnight. It is the only method that reaches a stain that has gone into the material.