Grease stains can be caused by a number of things including motor oil, cooking oils, animal fat, salad dressings, and fried foods. For light stains on washable fabrics, a simple laundry pre-treat is usually all that is needed to remove many stains. On dry-cleanable fabrics (or for heavy stains on washable fabrics), it's often necessary to use a solvent (dry spotter) to break down and remove the oil.
Three Basic Rules for Grease Stains
1. Act fast for best results. Fresh grease stains can be fairly easy to remove if you act quickly. However, once heated or left to oxidize (which can happen within a matter of hours), the stains will darken in color and become difficult, or even impossible, to remove.
2. Don't treat grease with water. Oils are hydrophobic, they don't break down with water. Grabbing a wet cloth to wipe up a greasy, oily stain will only make the stain bigger and more difficult to remove.
3. Before committing to any cleaning agent or technique, pretest it on an inconspicuous area of the fabric.
Treating Fresh Stains
Step 1: If any solid material remains on the surface of the fabric (e.g. a glob of butter or salad dressing) gently scrape off as much as possible using your fingernail or the edge of a spoon. Work outward from the center using light strokes. Take care not to press too hard or you'll drive the grease deeper into the fabric.
Step 2: Apply an absorbent like cornstarch, baking powder, or talcum powder to the stain and leave it on long enough to absorb as much of the grease as possible. This may take from 30 minutes to a few hours. To remove the absorbent, invert the fabric while holding it over a sink or garbage can and gently shake off the excess. Brush the stain gently with a stiff bristled brush.
Treating Older Stains (post-oxidation or heat)
Washable fabrics: Treat older grease stains from gravy, soup, mayonnaise, and other oily foods by applying a petroleum-based dish soap to the stain, allowing it to soak in for 30 minutes to 1 hour. After soaking, machine-wash the item in warm water. If the stain remains after washing, don't hot-air dry or iron the fabric. Let it air dry completely and try sponging it with a dry spotter. Tip: Use petroleum-based dish soap only. Plant-based soaps will not work. Also, to avoid discoloring the fabric use clear dish liquid only, nothing colored.
Dry-clean only fabrics: Using a cotton swab or a cloth pad, apply a dry spotter and a few drops of mineral spirits to the fabric, letting it soak in for a few minutes until saturated. Blot with a clean cloth and repeat until the stain is removed. When finished, dab the fabric with cool water and dry flat.
Dry-cleaning fluid (dry spotter): Dry spotters are effective in removing oily and greasy stains, especially from water-sensitive fabrics. They can be used on virtually any fabric without damage, and will not set stains. (Always perform a pretest just in case.) They are commonly available where laundry detergents are sold or can be purchased from local dry cleaners (K2r and Afta are common examples). Use them sparingly on upholstery and carpet, as these types of solvents tend to deteriorate the foam and stuffing used in upholstery cushions and the latex adhesives used to glue carpeting together. Dry spotters should only be used on dry fabric in a well-ventilated area (preferably outdoors). Never use them on clothing that you haven't taken off yet and keep them out of reach of children!
Laundry Pre-treats (combination solvents): These cleaning agents can help remove a lot of greasy stains just in the course of routine laundering. Pre-treats are applied and allowed to soak into the stain for a few minutes before washing (follow label directions). Common examples of pre-treats include Shout and Spray n Wash. Pre-treats need to be rinsed out or laundered after use, and should not be allowed to dry on the fabric.
Remember, there is no single technique or product that takes care of every stain on every type of fabric. If a fabric isn't washable or is very expensive, the absolute safest thing you can do is take it to a professional cleaner. Show them the stain and tell them (if possible) what caused it and what you have done to try to remove it. Then keep your fingers crossed and hope for the best!