Stewart Systems EkoEtch Aluminum Etch EkoEtch is a high concentrate combination acid based detergent and de-greaser. EkoEtch removes scale, corrosion, light oil, processing fluids, and brightens aluminum. EkoEtch is non-hazardous, water reducible, and nonflammable. Use EkoEtch to prepare both new and old aluminum surfaces before applying AFS primer/sealer or EkoPrime primer/sealer.