Pour the buttermilk (or yogurt) and oats into a blender. Blend until the mixture is smooth. (A blender works best, but you can do this by hand or with a mixer - it just takes a bit more work on your part.)
Wash and dry your face. Gently rub the oats and milk/yogurt mask onto your face. Let it sit for 15 minutes, and rinse with warm water. Any remaining mask can be refrigerated for up to three days.
Can this work with the buttermilk substitute: 1/2 cup regular milk and 1/2 Tbls lemon juice or vinegar?