The etching chemical may fail to react properly on the glass if the surface has any traces of grime, dust or residue prior to application. You must remove all potential barriers from the glass using water. Avoid using a glass cleaner, as it may leave a film behind. Dry the glass thoroughly after cleaning and avoid putting fingerprints on the etching surface by wearing gloves.
Another reason for an incomplete reaction with the glass surface is insufficient application of the cream. Apply a layer thick enough to completely cover the design of the stencil used underneath.
The chemicals in the etching substance can burn and irritate the skin, eyes and the respiratory tract when inhaled, according to FluorideAlert.org. Wear rubber or plastic gloves and a long-sleeved shirt when etching to protect your skin from contact. Use the cream near a water source, such as a faucet, and immediately wash away any cream that does get on your skin with soapy water. Wear protective glasses and work in a well-ventilated space.
Over time, rinsing your etching projects off over an enamel or porcelain sink may take its toll on the luster of the basin, especially if you use generous amounts of etching cream or use the product regularly. Rinse etching cream off over a stainless steel or utility sink to avoid this problem. You may also use a plastic bucket.