Acting as quickly as possible is the most important part of getting rid of a blood stain from a washable piece of fabric. The more time you give the stain to set, the more difficult it will be remove it. Soak excess blood from the stain by blotting it with a paper towel. To avoid damaging the dyes and fibre, make sure you do not rub the stain.
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With cold water, flush the blood stain as soon as you finish blotting it. This should remove most of the blood but the stain will still remain.
Prepare a paste by mixing powdered detergent with a small quantity of water. The paste needs to be fairly thick so do not use too much water. Apply this paste on the stain. Now you can either launder the fabric or soak it in an enzyme pre-soak. Keep the fabric soaked for a while after which your need to rinse and launder the fabric again.
The stain may still be remaining on the fabric. If that is the case, you need to use a few drops of ammonia. There will be a seam on the inside with instructions about colour change from the manufacturer. Remember to read those instructions before using ammonia to get the blood stain out. If the use of ammonia is will not damage the fire, apply a few drops of ammonia on the stain and you should be able to get rid of it. In case you do not have ammonia at your disposal, using 3% hydrogen peroxide instead.
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If none of the treatment works, you should soak the fabric in laundry pre-soak bleach. Usually, warm water works best, but when removing a blood stain, cool water should be used. Leave the fabric soaked for at least 30 minutes before washing it with cool water.