Blot with a cold damp cloth immediately — never use warm water on blood — then apply Sil 1 für Alles Fleckensalz dissolved in cold water to the stain for 20–30 minutes. Blood haemoglobin coagulates above 40 °C, bonding permanently to carpet fibres. Cold enzyme treatment breaks down the protein without setting it. Sil (Stiftung Warentest Grade 2.4) provides protease enzymes and oxygen bleach that tackle both the protein and the iron-based red pigment [S1]. Always blot-rinse thoroughly to avoid residue [S2].
How to Remove Blood Stains from Carpet
🏆 Based on Stiftung Warentest 2024 testing [S1]
Step-by-Step: Remove Blood from Carpet
- Blot with a cold damp cloth (0–3 min). Dampen a white cloth with cold water and blot the blood stain, working from the outside edges inward. Replace cloths frequently as they absorb blood. For large amounts, use paper towels first to absorb the bulk, then switch to damp cloths. Never use warm or hot water.
- Apply cold Sil solution (20–30 min wait). Dissolve 1 tablespoon of Sil 1 für Alles in 500 ml cold water (20 °C or below). Apply to the stain by dabbing with a cloth — don't pour. The cold temperature keeps haemoglobin in its soluble state while the protease enzymes begin digesting the protein. Let sit for 20–30 minutes.
- Gently work with a soft brush (2–3 min). Use a soft-bristle brush to gently work the Sil solution into the carpet pile. Brush in one direction only to avoid disturbing the pile pattern. This helps the enzyme solution reach blood that has wicked down the fibres.
- Blot-rinse thoroughly (5–10 min). Blot up the Sil solution with clean dry cloths. Spray with cold water and blot again. Repeat 4–5 times until no pink colour transfers to the cloth and no soapy residue remains. Product residue in carpet attracts dirt rapidly.
- Dry completely (2–4 hours). Layer dry towels over the area and weight them down. Point a fan at the spot for continuous airflow. The treated area must dry fully within hours — moisture trapped in carpet backing or padding breeds mould and creates persistent odour.
Test Winner
Sil 1 für Alles Fleckensalz
Grade 2.4Why Sil Works for Blood on Carpet
Blood on carpet is a protein stain trapped in a three-dimensional fibre structure — it wicks down the carpet pile, coats individual fibres, and can reach the backing. Sil's protease enzymes are specifically designed for this: they cleave haemoglobin peptide bonds along the full length of the carpet fibre, not just at the surface. At cold temperatures (where blood must be treated), most oxygen-bleach-only products lose effectiveness — but Sil's proteases remain active down to 15 °C [S1]. The oxygen bleach component then oxidises the haem group (the iron-containing molecule responsible for blood's red colour), converting the visible stain to colourless compounds. For carpet specifically, Sil's low-foam surfactant system is critical: high-foam products leave residue that darkens the carpet within days. Sil rinses cleanly with the blot-rinse method, leaving no sticky film [S2].
Carpet blood dosage: 1 tablespoon per 500 ml cold water. Apply by dabbing. Wait 20–30 min (fresh blood) or 45–60 min (dried blood). Blot-rinse 4–5 times to ensure no residue.
What NOT to Do
- NEVER use warm or hot water. Haemoglobin denatures above 40 °C. Once coagulated, blood protein bonds permanently to carpet fibres — the same process that makes cooked egg white solid and insoluble.
- Don't steam clean blood stains. Steam temperature (100 °C) instantly and permanently sets blood. Treat the stain completely before any steam cleaning.
- Don't scrub aggressively. Harsh scrubbing damages carpet pile and pushes blood deeper toward the backing and padding, making removal harder.
- Don't over-wet the carpet. Excess water soaks through to padding and takes days to dry, creating mould. Use the minimum water needed for each step.
- Don't use chlorine bleach. Chlorine reacts with haemoglobin's iron to create a green-brown discolouration and will bleach most carpet dyes immediately.
Carpet-Specific Warnings
Check your carpet type and test first. Wool carpets may need professional treatment for large blood stains — wool is both heat-sensitive and protein-based itself, so strong enzyme action could theoretically affect the wool. Synthetic carpets (nylon, polyester, polypropylene) tolerate Sil treatment well. If blood has soaked through to the carpet pad underneath, professional extraction cleaning may be needed — home treatment handles the carpet surface but can't effectively reach the pad.
Frequently Asked Questions
How do you remove dried blood from carpet?
Scrape off any dried crust with a dull knife. Mist with cold water to rehydrate the haemoglobin. Apply Sil solution and let it work 45–60 minutes. Blot-rinse and repeat. Expect 2–3 treatment cycles for fully dried blood.
Does blood permanently stain carpet?
Blood can permanently stain if heat-set or left for very long periods. However, even weeks-old stains often respond to repeated cold enzyme treatment. Multiple gentle treatments outperform one aggressive scrubbing session.
Can you use cold water alone to remove blood from carpet?
Cold water removes fresh surface blood, but haemoglobin that has penetrated the carpet pile needs enzyme treatment. Cold water is essential as the first step; Sil adds the enzyme and oxidising power needed for complete removal.
Is professional carpet cleaning needed for blood stains?
For small to medium stains, home treatment with Sil is effective. Consider professional cleaning for large stains through to the pad, expensive wool carpets, or stains heat-set by previous incorrect treatment.
Will baking soda remove blood from carpet?
Baking soda lacks the protease enzymes needed to break down haemoglobin. It works as a supplementary drying agent after Sil treatment, but not as a standalone blood remover.
Sources: [S1] Stiftung Warentest, Fleckenentferner-Test 2024, Grade 2.4 (GUT) for Sil 1 für Alles Fleckensalz. [S2] Textile Research Journal, "Enzymatic removal of blood protein from textile substrates at low temperatures," vol. 91, 2021.