Accidents happen and whether it’s a child with a nose bleed, an animal with an injured paw or a more serious injury, it’s not uncommon for blood to make it onto household carpets.
The science of blood stains
Unfortunately, it can be particularly tricky to remove blood stains. This is because the main component in red blood cells, aside from water, is haemoglobin – a protein that binds to carpet fibres and isn’t soluble in water.
In the body, haemoglobin contains iron molecules, which bind to oxygen and give blood its colour. When blood lands on a carpet, the haemoglobin begins oxidising, causing the blood to look red. As the blood dries, however, the haemoglobin breaks down and both the iron and oxygen are released, causing the blood to change from red to dull brown.
Blood is notoriously difficult to remove. Even at crime scenes that appear clean to the naked eye, forensic scientists may find blood residues, and scientists have recovered blood traces left behind hundreds of years ago.
Don’t despair though! Provided you know what you’re dealing with, it is possible to get visible blood stains out of a carpet.
What to remember about blood stains
First it helps to know what not to do. It’s important to remember that heat will fix a blood stain, setting the protein (much like heat sets egg white) and making it harder to remove. So don’t use hot water.
Also note that cleaners like normal soap and dish-washing liquid are lipases, designed to remove fat and grease. They won’t help you one bit with removing a protein-based stain like blood.
It isn’t always possible to treat a blood stain straight away because injured people or animals obviously take priority over carpets. However, the sooner you get to a blood stain, the better.
Steps for cleaning blood out of a carpet
1. Blot or, if dried, loosen with a brush
To remove a blood stain that’s still wet from a carpet, you should start by using paper towel or absorbent pads to blot up as much of the blood as possible. To keep from spreading the stain, work from its outside borders inwards. Avoid scrubbing, which will simply grind the blood further into the carpet.
If you’re dealing with blood that has already dried, start by using a cleaning brush to break up and loosen the blood particles. Don’t be too rough though or you could damage the carpet fibres.
2. Spray with clean water and blot
The next step is to spray the affected area with clean water. Then blot up as much of the liquid as possible.
3. Apply cleaning solution and blot
After spraying with water, spray the affected area with an appropriate cleaning solution. The most effective options are to use either one part hydrogen peroxide to one part water or one tablespoon of ammonia mixed in half a cup of water. However, always test a hidden corner for colour fastness first.
A safe alternative for most carpets is to use one third white vinegar to two-thirds cool water. For a pure wool carpet, however, stick to a small amount of a non-alkali detergent mixed in water.
Leave the cleaning solution to sit for a minute and then blot up with an absorbent towel. If necessary, repeat the process up to two more times.
4. Rinse and cover with a weighted towel
Spray the affected area with water and blot again to remove the cleaning solution. Then cover with an absorbent towel or several sheets of paper towel. Add a weight, such as heavy books, on top of the towel and leave for several hours to absorb remaining liquid.
5. Air dry and then vacuum
Finally, remove the towel, leave the affected part of the carpet to air dry and then vacuum the carpet to lift up its pile and restore its original texture.