Good surface wettability is essential to obtaining reliable/strong adhesive bonds. Surface contamination can effect long term durability/load bearing capacity of bonded joints. After determining the source, type, thickness, amount of contamination strict quality control standards should be enforced to alleviate all surface cleanliness issues. This is often accomplished by the use of detergent/soaps or solvents. Common types of contaminants consist of dust, dirt, cutting oils, lubricants, mold release agents, waxes. Contamination can occur during fabrication from rags, finger prints, heat sources, compressed air, cleaner residue. Parts can be scrubbed/sprayed with soap/detergent or exposed to solvent immersion/vapors to avoid unexpected bond failures.
Inadequate cleaning can cause partial/complete separation of the adhesive from the substrate. It is important to note that in order to achieve desirable performance characteristics that surface cleaning should be performed in conjunction with other diverse treatment options. These may include mechanical abrading with emery cloth, wire brush, sandblasting steel, wool, chemical methods or physical techniques such as corona discharge/flame treatments. This is dependent on the substrate, configuration of part, service conditions and life expectancy of bond. Length/steps in the assembly process, environmental compliance and budget constraints should also be considered.
