How to remove baby sick from slate
Published by The Stain Library. How we research our methods.
- DifficultyModerate
- OutlookOften removable
- MaterialSlate
- Reviewed7 September 2026
The short answer
Press kitchen roll into the riven surface rather than wiping across it, because the hollows in a cleft slate face hold liquid where a flat cloth cannot reach. Wash with mild detergent in warm water and work it with a soft brush. Be aware that detergent strips slate sealer and slate oil, so a cleaned patch can end up looking lighter and drier than the floor around it.
If it has just happened
Press kitchen roll down into the texture rather than wiping across it. On riven slate a wipe passes straight over the hollows where most of the spill actually is.
Never combine hydrogen peroxide with vinegar
Mixing hydrogen peroxide and vinegar makes peracetic acid, which irritates skin, eyes and airways. Both appear in stone cleaning advice for different purposes, so keep them apart: use one, rinse the surface, let it dry, and only then use the other if you genuinely need to. The stone trade body gives the same warning about bleach and ammonia, which together produce a toxic gas.
Avoid heat while treating the stain
Avoid adding heat while treating this stain. Follow the material's care instructions and the method below; heat may make a mark harder to remove or damage the material or its finish.
Test on a hidden area first
Use only a cleaner allowed by the material's care instructions. Test it on an inconspicuous area with the same material and finish, or a matching offcut. Let the test area dry and check for changes in colour, texture or finish before treating the visible mark.
Cleaning the mark is not the same as disinfecting
If the sickness came with a stomach bug rather than an ordinary posset, the surface may carry norovirus, which spreads easily and survives on hard surfaces. UK public health guidance is to wear gloves, avoid shaking contaminated laundry, wash affected laundry separately with normal powder at 60 C where the care label allows it, and disinfect compatible hard surfaces with a bleach based product afterwards. Do that after the stain work, not instead of it, and only where the material tolerates it.
Keep every kind of drying heat away until the mark has gone
Baby sick is mostly milk protein. Heat coagulates protein and locks it into the material, which is why a mark that would have washed out can become permanent after one hot wash, one pass with an iron, a hairdryer or a spell on a radiator. Cool or warm treatment, air drying, and a proper look in daylight before anything warm goes near it.
What you will need
- Disposable gloves Sickness that came with a stomach bug is a hygiene job as well as a stain.
- A plastic spatula or a spoon Plastic, not metal. Metal scores stone and leaves a grey mark on pale surfaces.
- Kitchen roll and soft cloths For blotting rather than wiping, because wiping spreads a spill across more porous surface.
- Warm water and washing up liquid What this is A little mild detergent in warm water is the routine clean the stone trade body specifies.
- Bicarbonate of soda The absorbent half of a poultice, and the safe way to lift a mark out of a porous stone.
Helpful but not essential
- Hydrogen peroxide, 3 percent The active half of a poultice. The stone trade body names peroxide for organic stains.
- Cling film and masking tape To stop a poultice drying out in the first few hours.
Fresh baby sick on slate
Speed decides how much soaks in, and blotting decides how far it spreads.
Go carefully with warm water
Slate tolerates warm water only within limits. Keep contact time short, work from the edge of the mark inwards and stop if the material changes.
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Blot, do not wipe
Press kitchen roll onto the spill and lift. Wiping spreads it across more stone, and porous stone absorbs everything it touches.
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Lift the solids with a plastic spatula
Plastic rather than metal, because metal scores stone and leaves a grey graphite-like mark on pale surfaces.
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Wash with mild detergent and warm water
A soft cloth with a little washing up liquid in warm water, which is the routine clean the stone trade body specifies. Rinse with clean water and dry with a soft cloth.
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Look at it again once it is properly dry
Stone looks darker while it is damp and can look clean when it is not. Give it a few hours, look in daylight, and only then decide whether anything has soaked in.
Dried baby sick on slate
A poultice draws the mark back out of the stone. It takes a day and there is no faster version.
Go carefully with warm water
Slate tolerates warm water only within limits. Keep contact time short, work from the edge of the mark inwards and stop if the material changes.
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Clean and dry the area first
Mild detergent and warm water, then let it dry completely. A poultice on a dirty or damp surface works on the dirt rather than on the stain.
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Mix the poultice
Mix bicarbonate of soda with 3 percent hydrogen peroxide into a paste about the consistency of thick yoghurt. The stone trade body names hydrogen peroxide for organic stains indoors, and baby sick is an organic stain. Do not add vinegar or any acid to it.
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Cover it and leave it
Spread the paste about half a centimetre thick over the mark and a little beyond it, cover with cling film taped at the edges, and leave it for a day. The film stops it drying out in the first few hours, which is when it does most of its work.
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Lift it off and let the stone dry
Take the film off, let the paste dry completely, then lift it with a plastic spatula and wash the area. Judge the result only when the stone is dry.
Old or set in baby sick on slate
Repeats are normal. Knowing when to stop is the useful part.
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Repeat the poultice, fully dry in between
Stone specialists describe two or three applications on an older mark as normal rather than a sign that anything is wrong. Let the stone dry completely between them.
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Check whether it is a stain or damage
A stain is darker than the stone around it. Etching is duller rather than darker, and it is acid damage to the surface. No poultice touches etching.
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Look at it dry, in daylight
Damp stone is impossible to judge. Every decision here is made on dry stone by a window.
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Then call a stone restorer
They can hone and repolish an area, which is a different set of tools rather than a stronger bottle. On a floor, a worktop or a fireplace, a patch that does not match is worse than the mark, so this is a judgement worth paying for.
What not to use on slate
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Scouring powder, cream cleaner and wire wool
The stone trade body warns that scouring powders and creams contain abrasives that scratch stone. On a polished or honed surface that shows as a permanent dull patch, which is worse than the stain.
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Wiping a fresh spill rather than blotting it
Wiping spreads liquid across more porous surface, and every extra square centimetre it touches is more stone for it to soak into.
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Mixing bleach and ammonia, or peroxide and vinegar
The stone trade body warns specifically that bleach and ammonia must never be mixed. Peroxide with an acid makes peracetic acid. Both combinations appear in stone cleaning advice for different purposes, so keep them apart.
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A steam cleaner
Steam forces moisture into a porous stone and into the joints, and heat sets milk protein at the same time.
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Vinegar, lemon juice and acidic cleaners
The stone trade body says acidic cleaners are not recommended even on stones that are not calcareous, because they can contain traces of acid sensitive minerals, and acid also attacks the cement in any grout around them.
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Scraping a dried mark off with anything hard
Some slate delaminates at the surface and a scraper lifts a thin flake off with the mark. Soften it with warm soapy water and a soft brush instead.
White compared with coloured slate
Sealed and oiled slate is markedly darker and richer than bare slate, and detergent takes that finish off in the area you clean. The result is a patch that is lighter than its surroundings even though it is perfectly clean. If that happens, re-oiling or resealing the whole floor evens it out, and doing the whole floor rather than the patch is the only way to get a consistent result.
Products that genuinely help here
Try the household route above first. These are worth buying only when it is not enough.
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Optional product
Pure Safe hydrogen peroxide 3 percent solution, 500 ml
For a mark held in the riven surface
Baby sick is an organic stain, and hydrogen peroxide is what the stone trade body names for organic stains in stone. There is no household substitute for it in a poultice, and the bicarbonate of soda that makes up the other half is already in most kitchens.
Worth knowing. Press the paste into the hollows rather than spreading it flat, or it will bridge over the mark rather than touching it.
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If the mark is still there
Let it dry and look at the texture rather than the colour. Residue caught in the hollows shows as small light flecks when the slate is dry, and a soft brush with warm soapy water reaches them.
If a shadow remains in the stone rather than in the texture, a poultice works, though it is harder to keep in contact with an uneven surface. Press the paste in firmly and cover it.
If the treated area is now lighter than the rest, that is the finish rather than the stone. Slate dressing oil or a stone sealer restores it, applied to the whole floor or at least the whole flag, because a treated patch within a flag will always show.
When to stop and call someone
Call a stone specialist rather than continuing if the mark is held in the riven texture and will not brush out, if a treated patch is now visibly lighter because the sealer or oil has been stripped, or if the surface has begun to flake. Re-sealing or re-oiling a whole floor evens out a patch and is the usual fix.
Why baby sick behaves this way on slate
Slate is a fine grained metamorphic rock that splits into thin sheets along its cleavage.
The riven face is the natural split
Which means ridges, hollows and small terraces across the surface. Liquid collects in them and a cloth bridges over. Pressing and brushing are the techniques that reach them.
The chemistry is easy
Siliceous, so acid is a precaution rather than an absolute. That said, slate floors usually have cementitious grout between them and acid does attack that.
The finish is what you strip
Most domestic slate is sealed or dressed with slate oil, both of which come off with detergent. That is the most common way a slate floor ends up patchy after a spill.
It can flake
Some slate delaminates at the surface. Scraping at a dried mark can lift a thin flake, which does not go back.
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Sources
What we checked and when. Where a manufacturer instruction disagrees with anything here, follow the manufacturer.
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Care and cleaning of natural stone, Natural Stone Institute
trade body
Stone trade body guidance that calcareous stone such as limestone and travertine is sensitive to acid so only mild non acidic cleaners are used, that acidic cleaners are still not advised on granite, slate or sandstone because they can hold acid sensitive minerals, that scouring powders scratch stone, that the routine clean is a neutral cleaner or mild washing up liquid in warm water, that organic stains are treated with hydrogen peroxide, and that ammonia and bleach are never mixed.
Checked 7 September 2026
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Sick happens: how to get vomit out of carpet, National Carpet Cleaners Association
trade body
UK carpet cleaning trade body method for vomit: scrape solids with a blunt spatula or spoon, apply equal parts white vinegar and water, blot gently working towards the middle of the mark rather than outwards, never scrub because that drives the vomit deeper and damages the carpet, use only a small amount of warm water on a dried mark, and expect rehydrating it to release the smell again so ventilate.
Checked 7 September 2026
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How to remove baby formula stains, Purex Stain Lab
manufacturer
Manufacturer guidance identifying breast milk, formula and baby spit-up as protein stains, explaining the role of enzymes, and warning that the mark should be checked before any drying heat because heat sets what remains.
Checked 7 September 2026
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Norovirus: what to do and how to stop the spread, UK Health Security Agency
authority
UK public health guidance establishing that illness related vomit can carry norovirus, that contaminated laundry should be washed with normal powder at 60 C where the care label permits, and that compatible hard surfaces should be disinfected with a bleach based product.
Checked 7 September 2026