DIY How to stain a concrete floor using acid-based stain! This site (by DIY-ers) has the most thorough & easy step-by-step instructions I've seen yet. Be sure to read *everything* on this site, as they perfected their own stain formula for quickest application. You can do this, too!
Concrete Stenciling with Acid-Etching Gelhttp://www.concretenetwork.com Watch a concrete stencil being applied and used with acid-etching gel. The surface was previously acid stained to get the brown/tan color. The acid-etching gel will remove some of this color leaving a stenciled pattern.