Every aerosol consists of two elements - the propellant and the product itself, whether a liquid, foam or semisolid.
Three kinds of propellants are used: hydrocarbons (liquid propellants), carbon dioxide (a compressed gas) and dimethyl ether.
Hydrocarbons are effective as propellants because as the product is used up they turn to vapor and fill the void left by the decrease in product.
Carbon dioxide is not efficient for some products because it does not maintain a constant pressure. Carbon dioxide is most efficient where coarse, wet spray is needed and the distance from the can to the surface is short.
Tamper-resistant, transparent caps discourage youngsters from pushing spray buttons as they browse through a store. Their use assures customers that cans are full and in working order.
Some overcaps are designed to be tamper resistant in themselves, requiring a screwdriver or other tool for removal. They lessen the chance of spraying the aerosol in the user's face or the wrong direction.
Adults should be cautioned about inhaling too much of the propellant gases. Data suggests that substantial amounts inhaled may be harmful to health. Aerosols are effective and safe, as long as the product is used in well-ventilated areas.
Valve modifications have improved the spray pattern of aerosol paints. Some permit spraying in any position, even upside down.
The first place to evaluate quality in aerosol paints is on the can. See what percentage is paint and what percentage is propellant.
The "fill ratio" used by manufacturers will vary. So will the kinds of propellant.
The most common propellant is a hydrocarbon - fairly lightweight. A common fill ratio for a hydrocarbon is about 77 percent/23 percent. That means a 16 fl. oz. can would contain 10 oz. of paint by weight and only 3 oz. of propellant.
Besides the propellant and fill ratios, the paint formulation can vary. Some formulas cover better; others last longer; some provide a brighter gloss.
Aside from quality differences, paints used in aerosols are classified by type of finish and length of wear. Generic terms such as enamel and lacquer are used, but encompass a variety of film-forming resins with differing characteristics. Read labels and manufacturers' literature for a description of actual features.
Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.
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