What Chemicals Do I Use When Restoring My Car And When Do I Use Them?
We often mention in our articles that, in preparation for painting or powder coating, we wiped the surface of some part or panel with various chemicals. Many of our subscribers have asked what these chemicals are and when each should be used. Therefore, we thought it was high time to list the most common materials used in a typical restoration project and what each does.
Also, we've given a short explanation of the hazards involved in using various chemicals. When using any chemical, always read the safety precautions thoroughly. Some of these things can be deadly or produce permanent injury, so take the time to familiarize yourself with them.
Lacquer paints aren't used much anymore, chiefly due to their inferiority to modern finishes coupled with the toxic nature of their solvent. Lacquer thinner is a very stable solvent, used for all types of thermoplastics (including inks, fingernail polish and some adhesives.)
Lacquer thinner is composed of three organic compounds: Toluene, Methyl Ethyl Ketone and Methyl Isobutyl Ketone. The ratios are typically 50%, 25% and 25% respectively. Lacquer thinner is flammable and colorless. Overexposure to vapors can cause dizziness, confusion and nausea.
Other than thinning lacquer for finishing, thinner is used for a wipe-down of surfaces to remove residual films that might affect paint adherence. It is also used to remove many adhesive residues. It does not remove silicones very well.
Metal prep is a cleaner and conditioner for bare metal. It is composed of phosphoric acid and glycol ether. When spread over bare metal it reacts with the surface molecules to form a light coat of zinc phosphate that protects the metal from moisture. Rust, therefore, has a difficult time forming under the surface. Most finishes can be applied directly over a surface that has been coated with metal prep, but we tend to wipe it down with Prep Sol, followed by whatever solvent we're using for the paint or primer.
Metal prep is soluble in water and is generally only mildly toxic unless vaporized by heat. It is always advisable to wear rubber gloves and protect eyes from the irritating effects of contact.
Trichlorethlyene (Carburetor Cleaner)
Trichlorethlyene is a halogenated solvent. That is, it contains the halogen chlorine, which reacts with virtually any substance. This makes a very effective cleaning agent that has great effect on removing grease, films and some rust. It produces toxic vapors that are harmful to humans in sufficient quantities. It is also only cost-effective for cleaning small parts and will instantly "cloud" the surface of plastics.
It is highly flammable and toxic if ingested.
Mineral spirits is the name for what is a "light hydrocarbon" or "blended petroleum hydrocarbon solvent" used for degreasing and cleaning, as well as for thinning any oil-based paint or varnish.
Mineral spirits contain Stoddard Solvent*, hydrodesulfurized naptha, nonanes, n-propylbenzene, trimethylbenzenes, ethylmethylbenzenes, alkanes, isoparaffins and cycloalkanes, all of which come from the refining of petroleum.
*Stoddard solvent is a petroleum mixture that is also known as dry cleaning safety solvent, petroleum solvent and varnoline. The main trade name is Varsol.
Mineral spirits are flammable and toxic.
Prep Sol (3919S)
This is DuPont's name for its highly refined surface cleaner, composed chiefly of mineral spirits. It is a weak solvent with fast evaporation that very effectively removes wax, grease and silicones, and is considered vital for cleaning surfaces before finishing. It is the best substance to use for assuring that the surface of metal is ready for primer and finishes.
Sherwin Williams R7K156, Martin Senour 6383, PPG DX440 and BASF 900 also market the same formulation under these numbers. All are flammable and toxic if ingested.
Denatured alcohol is Ethanol, commonly called grain alcohol. It is prepared by passing ethylene gas at high pressure into concentrated sulfuric or phosphoric acid to form an ester, which is diluted with water. This renders it poisonous.
It is used to thin shellac, clean glass and metal and as a fuel for camping stoves. It evaporates very quickly and can be diluted with water to be used as an all-purpose cleaner on delicate items such as porcelain and some plastics.
Isopropyl alcohol, also known as isopropanol, is a colorless liquid with a pleasant odor. It is highly flammable. Isopropyl alcohol is found in alcohol sponges, cleaning agents, and rubbing alcohol (though some rubbing alcohols contain ethanol), and is a good disinfectant. It has few automotive uses other than for cleaning contacts, connectors and relays.
Methyl Alcohol (Methanol)
Methanol (methyl alcohol) is produced from the distillation of wood and is a clear, colorless, volatile liquid with a weak odor that is somewhat sweeter than ethanol. Products that are available in the home that contain methanol include: windshield wiper fluids and de-icers, antifreeze, glass cleaner, canned heat, paints, varnishes, paint thinners and removers. It can also be used in gasohol, which could present problems as people try to siphon the gas by mouth and accidentally ingest some. Methanol is well absorbed from the gastrointestinal tract mucosa as well as through the skin and lungs. Both inhalation and transdermal exposure can result in toxicity.
Ethylene glycol is a clear, colorless, odorless, viscous liquid with a sweet taste, which can produce dramatic toxicity. It is commonly found in homes and industry, most commonly in antifreeze, automotive cooling systems, and hydraulic brake fluids. In an industrial setting it is used as a solvent or as the raw material for a variety of processes.
Enamel paints are thinned with reducer. It is generally composed of Toluene, Aliphatic Naptha, Acetone, Butoxyethanol, Methanol, Xylenes and Ethylbenzene. It has very limited uses other than for thinning enamels, but is often used for final wipe-down of the surface before spraying. It is also the best material to clean the spraying equipment after painting with enamels. It is flammable and toxic if ingested.