If you have rust stains on some clothing or fabric, here's a sure-fire way to get the stain out. Boil enough water so that you can cover the stain. Once the water is boiling, remove it from the heat. Add cream of tarter at 2 tablespoons per quart of water and mix this into the water. Then add the clothing or fabric with the stain. Completely cover the stain and allow it to sit for an hour or so. Remove it from the water and then launder normally, the rust stain will be gone. Of course you'll only want to use this technique with fabrics that can withstand hot water.