Stubborn tar and nicotine stains must be handled differently than most stains. Water-based cleaning products won't soften and dissolve the tar and nicotine.
Vinyl and sealed wood blinds can be cleaned with a borax and lemon juice paste placed directly onto the stains. To remove this type of stain from fabric blinds, however, you need some oil-based pantry and cleaning products.
Glycerin, an oil that occurs naturally in corn, softens oil-based stains such as tar. Start your stain treatment by removing the blinds from the window; spread them out over a thick layer of paper towels.
Pour glycerin over the stains and gently tap it into the fabric with a toothbrush. The glycerin penetrates the tar and nicotine stains and pulls them through the fabric onto the paper towels.
Check the paper towels every few minutes and replace them with fresh ones as you see the towels absorbing the nicotine and tar.
Anyone who works with oil-based paints can attest to turpentine's ability to dissolve even the toughest paint stains. Turpentine penetrates and dissolves the oil molecules in the paint, and it can do the same on oil-based tar stains.
After you’ve softened the stain with glycerin, cover the stain with turpentine and eucalyptus oil. This should dissolve the rest of the tar and send it through the fabric onto the paper towels.
Continue replacing the paper towels as necessary.
Turpentine cannot be left on the fabric, or it will leave a stain of its own. Wash away the oils by rinsing the blinds with isotropy alcohol until the stains and oils completely wash through the fabric.
You may notice some residual spots around the treated area, from accumulated dust and dirt on the fabric. You can make your blinds look new by washing them completely.
Hang them on a clothesline and spray them all over with a carpet spot cleaner. Then hose them down thoroughly, making sure the water penetrates the fabric.
This pulls the remaining dirt through the fabric and washes away residual spots from treating the stains.