Paint Systems Paint goes on as a mixture of solids held in suspension in a liquid carrier. It's initially distributed on the substrate (the surface being painted) in the form of a wet film. The wet film hardens into a solid film by a combination or out gassing of liquid carriers and chemical reacting/linking of liquid molecules into solid compounds. As the cure occurs the physical dimensions of the film change, the resulting hard film tends to have greater surface area than the original wet film, the outer surface must contract in three dimensions to fit onto the two dimensional surface of the substrate. All paints consist of pigments resins, and solvents. The resin provides the coating material, with the pigments creating the desired colour, and solvents reduce the material to a workable viscosity. Envirobase is a waterborne basecoat that advances technology and chemistry to a new level. After decades of relying on chemical solvent-based formulations in automotive paints, PPG has turned the focus of development to a cleaner, simpler formulation that will drive the OEM and refinish industries deep into the new century, and do it faster. Innovative products, such as Cationic Electrodepositing (E-Coat) and the latest waterborne basecoat, Envirobase™, are current examples of how automotive coatings from PPG continue to increase the painting process’ innovation and productivity – PPG website The oil content (Siloxane) of a paint system is 20-60 %, dependant upon manufacturer. The oils used in car care products provide the necessary lubrication for spread ability, and also they contribute to the depth of shine by providing the necessary fatty esters during the wax cure time. The oil-based paint, nitrocellulose lacquer or enamel and older technology paints on classic vehicles requires oils to keep them from becoming too brittle and cracking, water-based high solid/low solvent and urethane paints only require protection (as opposed to oil ‘nourishment’) Paint is a simple mixture of ingredients including pigments, a binder and diluents, or thinner (in a water-based paint it is water; in a solvent-based paint, it is petroleum solvent). Automotive paints utilizing modern paint technology using water-based high solid/low solvent urethane that for environmental reasons produce a much softer and more porous finish than acrylic or oil based high solvent content paint systems. Using permanent pigmentations and colorants specifically designed for automotive applications (containing automotivWater based paints Water-based automotive paint is classified as a semi-permeable membrane that has tensile strength and elongation (elasticity) to enable it to move along with the metal as it expands /contracts due to environmental temperature fluctuations Paint is a simple mixture of ingredients including pigments, a binder and diluents, or thinner (in a water-based paint it is water; in a solvent-based paint, it is petroleum solvent). Automotive paints utilizing modern paint technology using water-based high solid/low solvent urethane that for environmental reasons produce a much softer and more porous finish than acrylic or oil based high solvent content paint systems. Water-based automotive paint is classified as a semi-permeable membrane that has tensile strength and elongation (elasticity) to enable it to move along with the metal as it expands /contracts due to environmental temperature fluctuations Using permanent pigmentations and colorants specifically designed for automotive applications (containing automotive-grade binders). Albeit a non-toxic (less than 0.01-percent VOC) water-based paint, there are no compatibility issues with major-brand urethane and polyurethane clear coats. e-grade binders). Albeit a non-toxic (less than 0.01-percent VOC) water-based paint, there are no compatibility issues with major-brand urethane and polyurethane clear coats. •Aesthetics - the aesthetics of a vehicles appearance is very subjective to say the least, the only best wax or sealant that really matters is what looks 'best' to you. In the final analysis it all come down to; 85% preparation, 5% product, 7% application methodology and the balance is in the ‘guy’ of the beholder •Colour- the primary pigment is commonly composed of titanium dioxide. The amount of primary pigment impacts greatly on the hiding capabilities of the paint film and UV protection, secondary pigments are pigments such as talc, silica, calcium carbonate, mica, etc., which have little impact on hiding as they are basically used as fillers to help control viscosity, levelling, sheen, etc. •Binder- the binder system for the colour and clear coats is formulated from a single component melamine system (PPG Diamond Coat); which holds everything in the paint together (including the pigments) giving the paint its ability to bond, and endure the elements. •Resin- the resin is the film-forming portion of the paint, a synthetic or natural material used as the binder in coatings, can be translucent or transparent, solid or semi-solid. Examples: acrylic, alkyd, copal ester, epoxy, polyurethane, polyvinyl chloride, silicone oil. •Epoxy- by applying an epoxy coat as a sealer, which you can sand if you choose, the epoxy is the only oxygen air tight product used and will seal everything below it, nothing will soak or leech into the 2K primer, and it will also improve adhesion of the base coat and produce a stronger bond. Using the epoxy as a sealer is used mostly with restoration projects and / or by enthusiast detailers that have the time to wait and not rush things •Clear coat- is usually a two-part, high-solid, low-solvent polyurethane or urethane paint used to protect modern water-based paints as they provide a clear, tough and durable protection. Water-basted paints porosity allows the clear to absorb directly into the paint, creating an excellent bond that will not lift or peel (providing the paint has been applied properly) •Polyurethane-a tough, rubber-like elastomer based on the condensation of organic isocyanates with resins containing hydroxyl groups, also referred to as urethane. Mohs scale of Hardness A system of measurement to establish a guide as to the relative hardness of various materials, Mohs scale of mineral hardness was devised by the German mineralogist Frederich Mohs in 1812, selecting ten minerals because they were common or readily available. The scale is not a linear scale, but somewhat arbitrary. The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, and/or the softest material that can scratch the given material. For example, if some material is scratched by apatite but not by fluorite, its hardness on Mohs scale is 4.5 An adaptation of that scale; Talc =1 Carbon Black = 2 [black paint pigmentation] Copper = 3, Platinum = 4 Iron = 5, Glass = 6, Quartz or Titanium dioxide = 7 [white paint pigmentation], Topaz = 8 Corundum or Ruby = 9, Diamond =10 Paint Film Thickness Most modern vehicle paint film systems (paint build) comprise a primer coat of 2 Mil, a colour coat of 1-2 Mil, and clear coat of 2-3 Mil, an unprotected paint surface will lose approximately 8-10% or 0.4 Mil (0.0004-inch) to environmental exposure in a twelve month period (dependant upon geographic location) As a point of reference a sheet of copy paper is 3.5Mil (0.0035") removing more that 10% or 0.3 Mil (0.0003") of clear coat will cause premature paint film failure 1.5Mil (0.0015") a surface scratch that will `catch' your fingernail is approximately 0.004" deep will usually require wet sanding and refinishing. Using a moderate to light polish; and utilizing a rotary polisher will remove approximately 0.000025 - inches (0.635 Microns) from the paint surface (they are many variables such as polish/compound and speed / pressure used that may affect the paint removed) There comes a point when you must judge wither removing a scratch will compromise the clear coat and if so you’ll have to ‘live’ with the imperfection The clear coat provides protection from a hostile environment and an excellent brilliance, but is easily scratched; once it is compromised repairs involve re-painting, as the base colour has no brilliance, shine or depth, start with the least abrasive product to accomplish desired results, and only if necessary move up to the next grade of abrasive. Q: What is the "right" paint thickness for a vehicle? A: There is no "right" paint thickness for any vehicle. Automobile manufacturers paint thousands of vehicles each day with a wide variety of paint formulations; their specification has a range of thicknesses. For some models this can be as low as 3 Mil and, in the case of the rocker panels of Sports Utility Vehicles (SUVs), as high as 17 Mils. Q: If there is no "right thickness", what am I looking for? A: Paint thickness consistency; for example, when you are reading between 3.5 and 5.0 Mils and a reading shows a sudden reduction in thickness, you know there is a cause for concern in that particular area of the bodywork. Paint Thickness Gauge An electronic paint thickness gauge can be an invaluable tool, before buffing it’s always a good idea to check the paint film thickness to see how much of the paint film thickness is available, check periodically during the process and on completion to see how much was removed. Take measurements with a paint and coating thickness gauge (Check-Line Model DEF-900) All the major car manufacturers specify that measurements should be taken before, during and after these steps. This is primarily because removal of too much clear coat can cause paint failure over time due to the fact that UVR absorption is the job of the clear coat. If an insufficient thickness of clear remains after polishing the colour coat won't be protected from UV radiation. For this reason, it’s also recommended that paint be measured when buffing since you can’t see how much paint is being removed during the buffing process. If too much clear is removed, either on the original OEM finish or the refinished areas (colour coat 0.3–0.5 and total paint 1.8MIL thickness min) a warranty issue may develop down the road it’s interesting to note that painters must now demonstrate proficiency with an electronic paint thickness gauge in order to become certified to perform refinish warranty work for General Motors Corp. (GM) vehicles. OEM Paints PPG Protective and Marine Coatings, DuPont™ Performance Coatings, Spies Hecker® (part of DuPont, used mostly by European auto manufacturers) Glasurit, and BASF coatings, each of these companies have a range of several differing paints Avoid Dimethylsilicone (DMS) aliphatic hydrocarbon solvent based products, as they are migratory, entering into the substrate (resin binder system) and being a solvent they will slowly break down the polymers in the clear coat. In time you'll notice areas where the colour becomes opaque (dull) and you cannot polish the surface to regain its shine. They also release the plastizers from vinyl, rubber and paint; causing them to evaporate out of the substrate, leaving behind a dry inflexible surface. High or low solids (ratio paint / solvents) - high solids (60/40) that leaves more material (coverage) once paint has cure. Low solids (30/70) means the paint contains more solvents, once they have out-gassed (evaporated) leaves a thinner coat (paint thickness) Water based paints Are essentially low solids paints (up to 60% solvent), but they are legal because de-ionized water is used as the solvent (water is the most common solvent) as opposed to volatile organic compounds (VOC). In addition to the low solids aspect, waterborne paints have many other properties that help improve the performance and appearance. (See also Petroleum Distillates, Clear Coat, Paint Curing Solvents used for the spray painting process: - Aliphatic hydrocarbons (Mineral Spirits- V M & P, Naphtha) - Aromatic hydrocarbons (Toluene, Xylene) - Esters (Ethyl Acetate, Butyl Acetate) - Ketone (Acetone, Methyl Ethyl Ketone (MEK)) Various combinations are used along with other additives (retarders, accelerators, and levellers) to reduce the viscosity of the material to a spray able consistency and accommodate climatic conditions. Various Paint (Coating) Types- •Nitrocellulose Lacquer: This paint had rapid drying and low viscosity properties, applied with a spray gun leaving a hard dry finish in approximately. When polished, and waxed, it far surpassed in durability and appearance the qualities of the Japanese lacquers. •Synthetic Enamel: Alkyd or synthetic enamels proved to have superior qualities in film strength, adhesion, lustre, flexibility and durability over all previous paints. It dries by solvent evaporation, like the lacquer paints, but the resin remains soft and sticky when no solvents are present. It cures to a hard finish by absorption of oxygen, the curing process can be accelerated by heat. Unlike lacquer, when dry, it doesn't polishing to produce a high gloss finish. •Acrylic Lacquer: Chemists developed a substitute for nitrocellulose lacquer, using an acrylic resin as a base. The resins used in acrylic lacquer tend to be slightly brittle, with the addittion of a solvent for that softens the resins. Cellulosic resin is derived from cellulose (pure cotton). Acrylic lacquer was used extensively by General Motors (GM). •Acrylic Enamel: The development of acrylic enamel (harder and more durable) Chemically, it is a cousin to synthetic enamel, but is modified with acrylic resin, which is not soft and sticky with no solvents present. It cures further with air and unlike lacquers, which remain soluble in solvents, the enamel family is insoluble in solvent when cured. An acrylic resin is chemically any polymer whose basic monomers are chemical derivatives of acrylic acid. •Polyurethane Enamel: Polyurethane enamel was developed to withstand the severe stress of high speed airplane surfaces, which are subject to rapid temperature changes and flexing. This paint was much more durable than acrylic enamels. •Acrylic Urethane Enamel: Acrylic urethane enamels were developed to withstand environmental elements, such as acid rain and ultra violet (UV) radiation; it is the most durable paint to date. •Nanotechnology: CeramiClear uses micro sized ceramic particles to provide a durable finish Timeline that shows the progression of automotive paint finishes - 1924 - Spray painting was introduced and the only available material was nitrocellulose lacquer. 1929 - Alkyd enamel was introduced. It was tougher than lacquer and needed no compounding. Most manufacturers used either lacquer or enamel from this point on, depending upon availability and factory conditions. 1940 - Chrysler and Ford changed over to enamels exclusively. Metal flakes in paints were introduced by the aluminium industry. 1956 - Acrylic lacquer was popularized due to its better sheen and durability. GM went exclusively to the material. 1960s - Paints utilized chromates, lead and other heavy metal chemicals that produced durable finishes. Ford called its enamels "proselytized" paints. 1970 - The first aftermarket polyurethane enamel, Imron, was introduced by DuPont. It utilized a two-part chemical system that was extremely durable. DuPont experimented with waterborne solvents during this period. 1978 - High solids acrylic enamel becomes the paint choice of most manufacturers. These have the advantage of requiring fewer coats. 1982 - Base/clear coat paint system adopted as automotive paint system industry standard. 1987 - Water-borne primers introduced. These paints are not actually dissolved in water, but use water as the medium to help transfer the paint from the can onto the car. They took a long time to perfect at the factory level, during which many durability problems were encountered. 1989 - Water-borne base coats introduced. 1990 - Clean Air Act sets strict limits on volatile organic compounds (VOC) emitted during paint applications. Both Japanese and European car manufacturers began using metallic (polychromatic) paint that contained 100-300-nanometer mica chips in an acrylic paint with a clear coat. 1997 - Anti-chip primers become industry standard. Information resource 1.PPG website on paint problems 2.Akzonoble Paints 3.Glasurit, Advice on Paint and Paintwork Defects 4.Automotive Body Repair News (ABRN) 5.Benjamin Moore Paints 6.Automotive Detailing; Inside & Out; a Knowledge Base for the Perfectionist – by Jon Miller © TOGWT ™ Ltd Copyright 2002-2008, all rights reserved Detailing Articles This is one of is one of a series of unbiased and informative, knowledge based, subject specific articles, which are dedicated to the automotive detailing enthusiast or professional detailer in search of development and further education Copyright Protection and intellectual property rights-© This work is registered with the UK Copyright Service that supports international copyright protection by securing independent evidence that will help prove originality and ownership in any future claims or disputes. All original material is copyright, unless otherwise state (1) it may be copied and distributed for non-commercial purposes only provided that you retain all copyright and other proprietary notices contained in the original material, (2) the information is copied in full with no changes unless prior written agreement is obtained from TOGWT, and a reference to © TOGWT ™ is included, any unauthorized use of these materials may violate copyrights and/or trademarks
Revision to "Paint Systems Jan 2010 Applying a Polymer Sealant or Waxing New Paint A) Polishing or Waxing Fresh Paint This is only relative to re-painted surfaces that use a solvent –based paint. Modern environmentally friendly paint systems being utilized today are mostly water-base (EU), which evaporates quickly from the paint during the baking and drying process (US, only a limited number of painters are utilizing water-based paint). One of the most often asked question (besides Leather care and Glass cleaning) and a subject that results in a great deal of confusion and misinformation regarding polishing or waxing re-painted panels. The majority of refinish paint is supplied by BASF DuPont, PPG and Sherwin Williams is 2K polyurethane; one component is polyisocyanate and the second is a polyol (acrylic or polyester polyol). Water or solvent-based paints (which still constitutes the majority of what is still being used, despite VOC regulations) once the two components react they form a strong polymer chain. Newly applied paint is soft, much softer than OEM paint, while newly refinished paint is about 90% cured within 24 hours, although it does take up to 30 days for it to become fully cross-linked (even with the help of a drying oven and various additives). Automotive paint is classified as a semi-permeable membrane; some chemicals penetrate easily (solvents) During this period, using waxes or sealants that use a solvent as their carrier system should not be used since the solvents permeate the paint and soften it and if the wax or sealant contains abrasives, it can cause micro marring on the softened paint. The best products to use during this period are therefore water based systems that are both solvent and abrasive-free. Most paint shops use 10-20% more isocyanate component (hardener) than the polyol component. The reaction between these two (isocyanate and alcohol) is fairly rapid and that accounts for the 90% curing rate of the refinish paint within 24 hours. That leaves about 10% un-reacted isocyanate, some of these isocyanate groups slowly react with moisture (hence the term moisture cure) and form amine groups (releasing CO2). The newly formed amine groups rapidly react with isocyanate groups to form urea or polyurea, which is much harder than polyurethane adding solvents to the paint, hindering this reaction, while water-based products can help the (moisture) curing process. Professional painters add chemicals; accelerants and compounds to their paint mix prior to painting to improve flexibility, reduce paint imperfections, increase hardness, and improve gloss and some body shops heat it in a paint oven to harden the ‘shell’, it doesn’t reduce cross-linking times (this process is both temperature and time dependent) But I would suggest waiting for approximately ten to fifteen days before any abrasive product application, which should be more than sufficient time to enable paint off gassing and aerobic curing a) When a body shop wet sands and buffs out a newly painted panel they will hopefully polish out any sanding scratches, unfortunately this is not usually the case. Polishing paint that is at least 24 hours old is perfectly fine. But I would suggest waiting for approximately ten to fifteen days before any abrasive product application, which should be more than sufficient time to enable paint off gassing and aerobic curing (paint cross linking is both time and temperature dependent). Unless you are a very experienced detailer I would strongly advise against the use of heavily applied pressure and overtly abrasive products as they behave more aggressively on soft fresh paint. I would suggest you allow the fresh paint to fully cross-link (cure) before you attempt to remove any surface imperfections b) Automotive paint is classified as a semi-permeable membrane; it has both tensile strength and elongation (elasticity) newly painted surfaces are soft and full of out gassing solvents, resin binders and additives, as well as and water. Polish contains solvents, which soften the paint film, kinetic surface friction and applied downward pressure transfers its energy into heat / torque (force to rotate an object about an axis); c) Which causes the soft paint film to become thinner by elongation and the pad rotation to transmit shear stress (twist), which could result in the alteration of the paint films bond between its substrate, causing it to delaminate or tear? d) The heat makes the gasses expand (pV = nRT) the expanding gases go through a phase transition (change in density) and to relive this increased pressure they rupture the paint film surface, causing small fissures (similar to solvent pop) e) Once the outgas process is complete automotive coatings (paint) becomes a semi-solid permeable membrane, Being a polymer (elastomers) it remains flexible while retaining its tensile strength, to enable it to expand and contract to follow temperature fluctuations (elongation) kinetic friction and its associated heat can cause a rapid temperature rise (i.e. initial surface temp 80.oF, heat attained with a cutting foam pad at 1,100 RPM for approx. ten seconds is approx. 104.oF) the paint temperature can be checked by utilizing an instant read-out infra-red ‘gun’ thermometer, paint surface ‘spot’ temperature should be limited to 110.oF < In accordance with the Society of Automotive Engineers (SAE) a temperature of 115.oF will cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat. Also be aware that plastics and those surfaces that have flex agent additives have a different thermal rating and will be negatively affected by applied heat very rapidly. Fresh paint safe glaze’ - while a paint is cross linking, using solvent- based waxes or sealants is not ideal since the solvents penetrate the paint and soften it and will interfere with the outgas / cross linking process. The common ingredients in a’ fresh paint safe’ glaze are: water, glycerine or mineral oils(to produce a high shine) and a mild abrasive Kaolin (China clay) to burnish the surface and produce a gloss, some polymers are also formulated as ‘fresh paint safe’ for the same reasons The application of a specific ‘fresh paint safe’ or polymer type product, Zaino Polishes (exclude the use of either Z1 or ZFX™) Optimum Car Wax is water-based and is safe on fresh paint, or use Presta Fast Wax. Allow an ‘initial gas off’ (evaporate) /cure aerobic process of 7 days before application These products are completely safe for any fresh paint system as they allow the solvents in a water-based paint to outgas / aerobic cure process and provide some protection for any type of paint surface. After thirty days (30) the paint surface can be protected with a regular polymer sealant and/or Carnauba wax. Note: 1. DuPont, PPG and BSAF recommend a 90 day period; but any recommendation is dependent upon what paint, hardener, drying system, additives etc were used, the body-shop / paint manufactures know their products; seek their advice 2. Paint manufacturer have specific technical guidelines (see ‘Product Sheet’ or P-Sheet) on how to use their products to affect a warranted spot/panel/ repairs or a full repaint. This preserves both the paint manufactures and factory warranty (if offered) 3. Abrasive polish should be avoided until the paint has cured (an abrasive polish will not necessarily harm the soft new paint but unless it’s absolutely necessary I would avoid it) 4. Vehicle washing is encouraged but avoid car wash concentrates that contain any harsh detergents, alkali, acids, wax (recommended products- Zaino Z-7™ Show Car Wash, Groit’s Car Wash) also avoid car washes that uses a high-pressure spray, harsh detergents or brushes 5. Don't use a car cover until the paint is fully cured? 6. A paint film surface is a delicate thin coating easily dulled and very easily scratched, so choose carefully the advice you listen to and most importantly what advice you act upon. 7. Some Carnauba wax contains paraffin wax, which effectively ‘seals’ the paint surface more than a polymer due to its formulation. Place your hand in some paraffin wax; once the wax has dried (approx 1.5-2 hours) you'll notice that your hand starts sweating profusely because the pores have been ‘sealed’ by the wax. 8. The use of water-based products is highly recommended Washing Fresh Paint Freshly painted vehicle finishes are soft and easily penetrated by dirt and other airborne contaminants. This makes it especially important to wash your car more frequently during the first 30-90 days. Regular car washing is the easiest way to remove contaminants before they have enough time to bond to your paint finish and is a good practice to maintain the condition of your vehicle I would strongly advise against using commercial car washes due to the harsh chemicals that are often used and don't use an ice scraper or spill gasoline on the finish. (See also Washing and Drying Vehicle Paint) B) New cars - Original Equipment Manufacturer (OEM oven cured) Paint Original equipment materials (OEM) specified materials are very different from refinish paint products and materials The most often asked question and a subject that results in a great deal of confusion regarding polishing or waxing OEM paint. Paint curing process; new cars go through the painting and baking process without any of the rubber, plastic, and cloth components installed. This is why they can expose the cars paint to such high temperatures, these high temperatures and special paints used at the factory level ensure the paint is fully cured by the time the car leaves the assembly line. Original Equipment Manufacturer (OEM) water based paint and its clear coat is cured at high temperatures; OEM paints are cured in a paint oven at around 320. °F (160. °C) for 20 minutes, in multiple oven zones where the paint is baked with radiation and convection heat so that 90-95% of the paint systems out gassing has taken place, the additional 5-10% will cure within 2-3 days and the vehicle’s paint can be waxed the moment it is rolled out of the manufacturing plant. By not applying some sort of paint protection soon after purchase the customer is actually damaging the paint surface instead of helping it. Salesmen that advise a customer not to wax a car for 3-6 months are relying on old paint methods and are misinformed about the latest paint technology. The newer paints are catalyzed (a chemical reaction that cures the paint) lacquers and enamels needed an extensive time for the solvents to release, with modern water based paints this is not necessary. This is a huge problem in dealerships because customers tend to take the advice offered by a salesman who usually knows nothing about paint, rather than a trained paint professional. This goes a long way to understand why fairly new vehicles paint surfaces are in such bad shape even after a relatively short period of time. Cosmoline Nnow only used on imports i.e. Porsche, Volkswagen, BMW, etc but is no longer used in the US as it is not environmentally sound; apart from that it is much harder to remove than the shipping/storage wax modern car manufacturer’s use. A large percentage of new vehicles, both domestic and imports have either a shipping/storage wax applied (5:1 emulsion of paraffin and synthetic wax) which effectively ‘seals’ the paint surface more than a polymer due to its formulation. Place your hand in some paraffin wax; once the wax has dried (approx 1.5-2 hours) you'll notice that your hand starts sweating profusely because the pores have been ‘sealed’ by the wax, these coatings are applied within one to three hours after the vehicle is assembled, and after the painting process is complete, this protective sealant coating (sealant means what it says) It really does seal and protect the paint from the environment, a lot different from the detailer’s polymer ‘sealant’)it should only remain for 90 - 120 days maximum; otherwise it becomes very difficult to remove (Auto International’s AutoBody Prep) Vehicles from the USA, EU and many European builds, use the plastic transit film, however vehicles from Brazil, and some Asian models, still use shipping wax. An extract from one of a series of unbiased “Detailing Technical Papers” © TOGWT ™ Ltd Copyright 2002-2009, all rights reserved
