Vintage fabrics can make a charming additive to a sewer's stockpile, or "stash." Old tablecloths, aprons and even garments provide lovely sources of old fabric for various projects. Stains often come with the old fabric and can prove challenging to remove. If you don't want to risk machine washing the fabric, you have a few other options to attempt to banish the brown spots from your old fabric. Rule to the wise: If your fabric has sentimental or monetary value, always use caution when trying to remove spots and stains.
Determine what type of stained fabric you have. Natural fibres are more "fixable" than manmade fibres. Do a burn test if in doubt: Snip off a bit of fabric from outside a seam and burn with a match---ashes indicate natural fabric, while melting indicates a manmade material. Most manmade fabrics will not respond well to any sort of stain removal and may fall apart with cleaning. You will have more success with cotton or a natural blend.
Determine the colour or print of the fabric. You may be able to bleach solid-white sturdy cottons. Colours and prints may respond to a soaking in non-chlorine bleach.
Take minimally invasive steps first. Rub a paste of baking soda and water with an old toothbrush onto the stain. Allow to sit overnight. Rinse and repeat if necessary.
Try applying commercial stain remover spray or stick, then let the fabric soak in cold water overnight. Rinse. Repeat if necessary.
Saturate with white vinegar or lemon juice, then use an old toothbrush to rub in table salt. Rinse. Repeat if necessary.
Hand wash in mild detergent and hang to dry if the stain persists.
You can machine wash some natural fabrics from 1940 or newer on the "delicate" setting in cold water. Don't attempt any machine cleaning if the item has sentimental or monetary value.
Consult a dry cleaner as a last resort.
Some stains are there to stay. If you're using the fabric to cut and sew, you may have to cut around and discard the stubborn stain.
When in doubt, don't do it. Unless your investment in the fabric does not concern you, use caution when attempting to remove stains.