Paint is more than aesthetics; it affects the weight of the  aircraft and protects the integrity of the airframe. The  topcoat finish is applied to protect the exposed surfaces  from corrosion and deterioration. Also, a properly painted  aircraft is easier to clean and maintain because the exposed  surfaces are more resistant to corrosion and dirt, and oil does  not adhere as readily to the surface. Ethanol or denatured alcohol is used to thin shellac for  spraying and as a constituent of paint and varnish remover. It  can also be used as a cleaner and degreaser prior to painting. Isopropyl, or rubbing alcohol, can be used as a disinfectant.  It is used in the formulation of oxygen system cleaning  solutions. It can be used to remove grease pencil and  permanent marker from smooth surfaces, or to wipe hand or  fingerprint oil from a surface before painting.  A wide variety of materials and finishes are used to protect  and provide the desired appearance of the aircraft. The term  “paint” is used in a general sense and includes primers,  enamels, lacquers, and the various multipart finishing  formulas. Paint has three components: resin as coating  material, pigment for color, and solvents to reduce the mix  to a workable viscosity. Benzene is a highly flammable, colorless liquid with a  sweet odor. It is a product used in some paint and varnish  removers. It is an industrial solvent that is regulated by  the Environmental Protection Agency (EPA) because it is  an extremely toxic chemical compound when inhaled or  absorbed through the skin. It has been identified as a Class A  carcinogen known to cause various forms of cancer. It should  be avoided for use as a common cleaning solvent for paint  equipment and spray guns. Internal structure and unexposed components are finished to  protect them from corrosion and deterioration. All exposed  surfaces and components are finished to provide protection  and to present a pleasing appearance. Decorative finishing  includes trim striping, the addition of company logos and  emblems, and the application of decals, identification  numbers, and letters.  Methyl ethyl ketone (MEK), also referred to as 2-Butanone,  is a highly flammable, liquid solvent used in paint and  varnish removers, paint and primer thinners, in surface  coatings, adhesives, printing inks, as a catalyst for polyester  resin hardening, and as an extraction medium for fats, oils,  waxes, and resins. Because of its effectiveness as a quickly  evaporating solvent, MEK is used in formulating high  solids coatings that help to reduce emissions from coating  operations. Persons using MEK should use protective gloves  and have adequate ventilation to avoid the possible irritation  effects of skin contact and breathing of the vapors. A wide variety of materials are used in aircraft finishing.  Some of the more common materials and their uses are  described in the following paragraphs. Acetone is a fast-evaporating colorless solvent. It is used as  an ingredient in paint, nail polish, and varnish removers. It  is a strong solvent for most plastics and is ideal for thinning  fiberglass resin, polyester resins, vinyl, and adhesives. It is  also used as a superglue remover. Acetone is a heavy-duty  degreaser suitable for metal preparation and removing grease  from fabric covering prior to doping. It should not be used  as a thinner in dope because of its rapid evaporation, which  causes the doped area to cool and collect moisture. This  absorbed moisture prevents uniform drying and results in  blushing of the dope and a flat no-gloss finish. Methylene chloride is a colorless, volatile liquid completely  miscible with a variety of other solvents. It is widely used in  paint strippers and as a cleaning agent/degreaser for metal  parts. It has no flash point under normal use conditions and  can be used to reduce the flammability of other substances.  Butanol, or butyl alcohol, is a slow-drying solvent that can  be mixed with aircraft dope to retard drying of the dope film  on humid days, thus preventing blushing. A mixture of dope  solvent containing 5 to 10 percent of butyl alcohol is usually  sufficient for this purpose. Butanol and ethanol alcohol are  mixed together in ratios ranging from 1:1 to 1:3 to use to  dilute wash coat primer for spray applications because the  butyl alcohol retards the evaporation rate. Referred to as toluol or methylbenzene, toluene is a clear,  water-insoluble liquid with a distinct odor similar to that of  benzene. It is a common solvent used in paints, paint thinners,  lacquers, and adhesives. It has been used as a paint remover in  softening fluorescent-finish, clear-topcoat sealing materials.  It is also an acceptable thinner for zinc chromate primer. It has  been used as an antiknocking additive in gasoline. Prolonged  exposure to toluene vapors should be avoided because it may  be linked to brain damage. Toluene Alcohol Acetone Methylene Chloride Finishing Materials  Methyl Ethyl Ketone (MEK) Benzene 8-2