Quick answer
Blot fresh blood with a dry white cloth, then dab with cold water (never warm or hot) until the cloth stops picking up colour. For what is left, mix a teaspoon of dishwashing liquid in a cup of cold water, dab, blot, rinse with plain cold water and blot dry. Dried blood: scrape off the crust, soften with cold water, then use an enzyme cleaner and give it time. On wool, skip peroxide and ammonia and stick to cold water and a wool-safe detergent.
Why cold water is the whole game
Blood is mostly water and protein. Protein behaves like egg white: warm it and it sets, binding to the carpet fibre and turning a loose red stain into a brown one that will not shift. Hot water, a steam mop, a hair dryer or a hired machine on the hot setting all make a blood stain permanent. Everything in this guide is done cold, and the carpet is only warmed once the stain has gone.
The second rule is blot, do not rub. Rubbing pushes blood deeper into the pile and the backing and frays the fibre tips so the spot stays visible even after the colour is gone.
Fresh blood: the first ten minutes
- Press a dry white cloth or paper towel onto the spot and lift. Repeat with clean sections until nothing more transfers. White, so you can see what is coming up and so no dye moves the other way.
- Dab with a cloth wrung out in cold tap water. Work from the outside edge in so the stain does not spread. Blot dry between passes. Most fresh blood on synthetic carpet comes out at this step.
- Mix one teaspoon of clear dishwashing liquid in one cup of cold water. Dab it on, wait a minute, blot with a dry cloth. Repeat two or three times.
- Rinse: dab with plain cold water to lift the detergent, then press a thick pad of dry towel on the spot with something heavy on top for twenty minutes to wick out the moisture.
- If a pink shadow remains on a light synthetic carpet, dab on a little 3% hydrogen peroxide (the brown-bottle kind from the chemist) with a cotton bud, wait five minutes, blot and rinse. Test it on a hidden spot first: peroxide can lighten some dyes.
Dried blood
Dried blood has already set to some degree, so the aim is to re-wet it cold, break the protein down and lift it in stages rather than in one go.
- Scrape off any crust with a blunt knife or the edge of a spoon and vacuum up the flakes.
- Lay a cloth soaked in cold water on the spot for ten minutes to soften it, then blot.
- Apply an enzyme cleaner (the type sold for pet accidents, which is designed for protein) and leave it for the time on the label, usually 15 minutes to an hour. Cover it with a damp cloth so it does not dry out while it works.
- Blot, rinse with cold water, blot dry. Repeat the enzyme step once or twice if colour is still coming up. Patience beats pressure here.
- A salt paste (salt and a little cold water) left on the spot for a few minutes before blotting helps draw blood up out of the pile on cut-pile carpet.
Old blood on a light carpet can leave a faint brown halo even when the stain itself is gone. That is oxidised protein in the fibre and it usually needs professional chemistry and hot water extraction to flush out.
What not to use
- Hot or warm water, steam, a hair dryer or a heater pointed at the spot: all of them set the stain.
- Bleach: it strips the carpet dye along with the blood and leaves a pale patch that cannot be fixed.
- Ammonia, peroxide or alkaline cleaners on wool carpet: they can yellow, weaken or felt the fibre. Wool gets cold water and a wool-safe detergent only.
- Coloured cloths, and over-wetting. Too much water drives the blood into the underlay and can cause browning as the jute backing dries.
Blood on wool carpet
Wool is protein too, so anything that breaks down blood aggressively will attack the fibre. Blot, dab with cold water, then use a few drops of wool-safe wash (the kind sold for woollen clothing) in cold water. Work gently, keep it damp rather than wet, and dry it quickly with a fan. If a mark remains, leave it for a professional rather than escalating to peroxide or an enzyme product: an Adelaide carpet cleaner with wool-safe chemistry and controlled moisture can usually finish the job without damage.
When to call someone
Call a professional for a large area (more than a dinner plate), blood that soaked through to the underlay, blood on wool or a light carpet that has left a shadow, or anything that has been there for weeks. Hot water extraction with a protein pre-treatment removes what the surface methods above leave behind, and it rinses the spot so no detergent residue attracts dirt later.
In Adelaide, we treat set-in stains as part of a room clean ($45 per standard room, $120 minimum booking) and heavy stain treatment from $30 per area. We tell you before we start whether a mark is likely to lift.
Rather have it done properly? We are an Adelaide-wide carpet cleaning service with published prices: get a free quote or call 0481 614 304, 7 days a week.
