Why Do Blood Stains Form a Stubborn Ring?

Understanding why blood stains form a stubborn ring due to coagulation and surface tension. Explore cleaning methods for porous surfaces.

Why Do Blood Stains Form a Stubborn Ring?
Photo by National Cancer Institute / Unsplash

Have you ever wondered why wiping away drops of blood from a surface leaves behind a thin ring that is harder to clean?
Let's delve into the science behind this phenomenon.

Surface Tension

Blood contains plasma, red blood cells, white blood cells, and platelets.

When blood comes into contact with a surface, its unique composition interacts with the surface on a molecular level.

The proteins and other molecules in the blood create a strong adhesive force, resulting in the blood spreading out and adhering to the surface, increasing the difficulty of removal.


Once blood comes into contact with the air, it begins to coagulate.

This process causes the blood to become stickier and more resistant to traditional cleaning methods.

Consequently, wiping the blood can spread it further, leaving a thin film around the original spot.

Surface Porosity

The porosity of the surface also plays a role.

If the surface is porous, such as fabric or unfinished wood, the blood can seep into the tiny crevices, making it challenging to completely remove.

Chemical Reaction

Blood can undergo chemical changes when it interacts with certain surfaces.

For instance, the iron in blood can oxidize when exposed to air, leading to a change in its chemical properties.

This can result in a more stubborn stain that is difficult to eradicate.


Understanding the science behind the resilience of blood stains can help in developing more effective cleaning methods.

While it's important to act promptly to remove blood stains, it's also crucial to use appropriate cleaning agents and techniques to address the unique characteristics of blood as a stubborn stain.