The passage of the 1990 Clean Air Act Amendments (CAAA) significantly impacted adhesives used to chemically bond uncured rubber to a variety of substrates during the vulcanisation of the rubber. Up until this time period adhesives being used to bond rubber were typically 70 80% organic solvent. The solvent allowed the polymer constituent to go into solution and was an excellent medium for grinding the pigments, fillers, and curatives during adhesive manufacture. Most importantly the solvent is an excellent carrier for getting the non-solvent portion of the adhesive to the substrate in a controlled and uniform manner. In addition to the Title I CAAA regulations, Title III of the CAAA considers many of the solvents being used in adhesives as hazardous air pollutants (HAPs) and requires that emissions of these substances be controlled through the use of maximum achievable control technology (MACT). This generally includes emission control equipment such as incinerators or carbon absorbers but can also include the use of compliant adhesives that contain no hazardous air pollutants. Now that the emission of these solvents is regulated and continually being reduced under the CAAA, aqueous adhesives have been developed and water has taken the place of the solvent in this new generation of rubber-to-metal adhesives. Not only were the organic solvents replaced in the new aqueous formulations but also the heavy metals such as lead were eliminated.