Stencil sandblasting is one way to create delicate, intricate patterns on the surface of concrete. Another way involves placing hydrochloric acid suspended in a heavy gel over stencil patterns adhered to the concrete surface. Introduced as a proprietary product by Surface Gel Tek, Scottsdale, Ariz., under the trade name Tek Gel, two advantages of this system are that it is less messy than sandblasting and the profile of the relief is very uniform and not as deep.