Getting blood stains out of clothes sounds like it would be next to impossible. This is a misconception. Blood stains are not a curse that one must just learn to live with. By following a few very simple guidelines, you may be able to salvage that item that you were sure was lost.
The first thing you must realize about blood stains is that they are a biological substance. The make up of a stain is crucial when deciding what to use to remove it. Do you remember when you were a kid and you scraped yourself? Did your mom ever pour hydrogen peroxide on it? If she did, you may remember how it bubbled until all the blood disappeared. That is the exact theory behind removing blood stains.
You may have noticed lately that a lot of the new cleaners out on the market contain "oxy" somewhere in the title. This is because they nave realized the benefit of using oxygen-based substances as cleansers. More specifically, most of them use as their base H2O2, or good old hydrogen peroxide. Hydrogen peroxide has the wonderful property of being able to break down and dissolve most biological substances. This makes it a wonderful tool for removing blood. These new H2O2-based cleansers are usually quite effective, but a bottle of hydrogen peroxide is a much cheaper alternative.
When removing a blood stain using hydrogen peroxide, it is important that the stain is left intact. If the stain is in on a workable piece of fabric and is still fresh, you may want to try rinsing it with a strong stream of cold water. This will remove any excess blood so that the hydrogen peroxide can do it's job. If you have previously used other preparations in attempt to remove the stain, it is important that you rinse it clean with cool water and let it dry. Hydrogen peroxide works best when it works alone. Normally letting a stain dry is a big no-no, but in the case of blood, it's actually better. This allows hydrogen peroxide to break it down more effectively.
Once your blood stain is dry, pour a generous amount of hydrogen peroxide over the stain. This is preferably done over the sink. You will immediately see the H2O2 start to bubble. Once the bubbling has stopped, use a colorfast rag soaked in hydrogen peroxide to push the stain from the back of the fabric while blotting the front of the stain with a dry cloth. If some stain remains, repeat the entire process. Once all visible traces of the stain are removed, rinse the item in cool water and launder as usual. Before putting the item in the dryer, check to make sure all traces of the stain are removed. If some remains, allow the item to air dry and then apply more hydrogen peroxide, then launder again.
The best practice is to avoid blood stains altogether, but this may prove impossible to do sometime. By using the method above, hopefully you'll be able to save items that otherwise would have been ruined.