(DISCLAIMER: My shirt was, otherwise, ruined. I took a chance on this, because it was already too late, I thought. I cannot take responsibility for any damage this hint may do to your clothing. Do at your own risk!
Yesterday, I got a blueberry stain on my shirt (it's a long story - just suffice it to say that I now had a huge, blue stain!) The shirt was an off-white, kinda "tea-colored", cotton one.
When you get a stain from anything with tannins in it (such as wine or blueberries or something like this), the LAST thing you want to do is put any kind of soap on it. Soap sets tannins in fabric.
I did immediately put cold water on it. That did take some of the worst of the stain out. But, then I was left with a set-in, dark stain that went completely through the fabric. I knew the shirt was ruined.
Hydrogen peroxide is a wonderful substance! I've used it on other things to get stains like blood or perspiration out of totally white fabrics. So, I thought I'd give it a try on my blueberry stain. Worth a shot, huh?
Now, the secret is to DAB it. NOT rub it in. Just dab a little of it on and then walk away. That's all. You're going to think it hasn't done anything, but it is. It just needs a little bit of time to work. Just leave it alone and don't mess with it anymore.
Amazingly, it got rid of the entire stain!!! I was so pleasantly surprised! And, not only that, but it didn't affect the color of the shirt itself. I have a totally clean shirt again that doesn't need to be put in the garbage.
Trying it on a blueberry stain was just a fluke - I didn't realize it would work so well! But, it worked wonderfully!
Again, it can (potentially) bleach color out of clothing. So, you may not want to do this on something colored. But, if you're willing to take a chance (and, if the garment is ruined otherwise), it's worth a shot. And, if you ever need something to take a stain out of a white, cotton material, it definitely works in that case.