The key to removing coffee stains from silk is to begin the process before the coffee dries. It will be much more difficult to remove a stain that has been allowed to set. If you cannot completely remove the stain immediately, at least begin the process to minimize damage to the garment. Do not dry the area, as this will permanently set the stain.
Step 1 - Blot Stain
If possible, remove the item of clothing. Being very careful not to allow the coffee to spread or splash onto other areas, blot the stain with a white paper towel or clean rag. If you do not have immediate access to the required materials, blot the area with cold water. This will keep the stain from setting until you can tend it it properly.
Step 2 - Dab the Stain with Vinegar Solution
The best method to remove coffee stains from silk is to mix equal parts of distilled white vinegar and water. Lay a clean white rag under the stained area. Dip a corner of a clean white rag into the vinegar/water solution. Carefully blot the stained area, working from the center to the edges. Do not allow the area to become too saturated, as this will spread the stain. Continue blotting, re-wetting different areas of the rag.
Step 3 - Stubborn or Set Stains
If the stain is especially stubborn, you may need to resort to steaming the coffee stains out of the garment. First, lay a folded clean white rag onto the ironing surface (table, ironing board). Lay the garment, stain side down onto the folded rag. Sprinkle cornstarch onto the stained area. Lay a clean white rag on top of the garment. With the iron set on “steam”, set the iron onto the top rag. The silk will be protected by the rag layers. This will steam the coffee out of the garment.
Step 4 - Wash Garment
After the initial stain removal, hand wash your silk garment. Do not place it in the dryer or use any sort of heat to dry it. Heat drying will set any residual stain. Allow the garment to air dry, and inspect it thoroughly.
Step 5 - Soaking Especially Stubborn Stains
Should the coffee stains still be visible, soaking the garment in an oxygen based laundry detergent booster for 20-30 minutes may help. Mix oxygen stain lifter with water according to package directions. Soak the entire garment in the mixture. Remove, and wash by hand with an appropriate detergent. Allow the garment to air-dry. Inspect the stained area closely. If necessary, repeat Steps 3-5 until you are satisfied with the appearance of the garment.
Step 6 - Last Resort
Ultimately, there is always the chance that the coffee stains will not completely come out of the garment. There is also the possibility that with the removal of the stain, some of the original dye may be removed, causing uneven coloring of the garment. If the problem is the former, take the garment to a reputable dry cleaner. Be sure to explain what the stain is and everything you used on the stain. If, on the other hand, the color is now uneven, you may find it necessary to dye the garment.