Blog >> Tools of the Trade : Water Based and Solvent Based Paints
Nothing changes quite dynamically as the paint industry. With new and frequent formulations arising from paint manufacturers, it is no surprise that players in the market are constantly looking for ways to level their playing ground with other competitors for the biggest share of the demand for paints. Engagement with customers and investment in research and development is key. For the past 50 years, the paint industry has primarily been dealing in solvent based paints - paints that depend on an organic solvent such as white spirit or acetone in order to dissolve its components into a homogenous, well-blended mixture. However, with the advent of water based paints - paints that rely on water as its main solvent - it is apparent that the playing field has changed, resulting in several developments. With increasing stringency on VOC (Volatile Organic Compounds) emissions and fears of toxic effects on consumer health, corporations dealing in the production of paints and coatings must stay abreast of news and developments regarding regional and international regulations in order to maintain an edge in their business activities.
Solvent based paints, also known as 'oil-based' or 'alkyd' paints, are paints with an organic compound as its main solvent. Containing significantly higher levels of organic solvents than water based paints, a typical base-coat has a VOC solvent content of around 84% with the remaining 16% being pigments, binders and additives. They can be further classified as being made from synthetic, alkyd oils or linseed, natural oils.
Despite being in the industry for decades, solvent based paints have faced a variety of drawbacks that have inadvertently led to a recent decline in its consumer use. They give off a pungent odour and require a longer drying time - at least 16 - 24 hours, as compared to water based paints. As with all other forms of paint, solvent based paints undergo drying after application with a brush or spray gun. The organic solvent evaporates into the surrounding atmosphere and releases VOCs which may pose a hazard to human health.
Many countries are already in the process of limiting the release of such compounds into the environment through strict regulations and compliance terms especially onto manufacturers. In the United States, federal rules governing the use of VOCs have already undergone implementation under the banner of the Environmental Protection Agency or EPA's National Emission Standards for Hazardous Air Pollutants (NESHAP) guidelines. The EPA lists health risks posed by VOCs as eye and nose irritations, damage to various organs such as the liver and kidney as well as being possible carcinogens, just to name a few. States such as California have strictly banned the use of solvent based paints in automotive coating uses.
Solvent based paints, however, do have their advantages over their environmentally friendly paints counterpart. They possess better flow and appearance properties and are less susceptible to environmental conditions such as humidity and temperature especially during the curing phase.
Water based paints, also going by terms such as 'acrylic emulsions, waterborne acrylic coatings and acrylic latex coatings,' are a relatively recent formulation that has seen an exponential increase in its use. The typical waterborne base-coat is composed of 70% water, 20% solids and 10% solvent, which can be further divided into acrylic and latex paints. These paints dominate in the industry with its sales volume accounting for 80% of the residential market in the US.
Water based paints have a multitude of advantages over solvent based paints. In terms of their application, they produce a comparatively brighter end product, are more user friendly, have a less pungent odour and are easier to clean. Moreover, advances in paint technology in recent years have translated into higher quality water based paints that possess qualities equal or better than their solvent based counterparts. Its immensely lower VOC content makes it a great way for businesses to lower their VOC output in lieu of increasing government regulations and reduce their spending on environmental compliance advising.
Water based paints, however, are not without their flaws. Consisting mainly of water, they are affected to a large degree by environmental conditions such as temperature and humidity. Humid surroundings prevent the evaporation of water and thus greatly slows down the drying process. In addition, having water as a solvent presents challenges in the surface preparation stage of a coating project. Water is one of the two essential chemicals for rusting and corrosion to occur. Should water make contact with the substrate before protective coatings are applied, undesirable spot rusting may occur. Hence, formulations must account for the removal of water through the surface film before corrosion occurs.
In conclusion, we see older, less environmentally friendly paints and formulations being replaced by newer, more environmentally friendly paints. Water based paints seem to be paving the way for the industry as innovation spurs on further development for greener and performance optimized compositions. Moreover, intriguing research into alkyd latex resin technologies have opened up possibilities of combining performance advantages of solvent based paints with that of water based coatings. These water based acrylic alkyd hybrids provide for low VOC levels coupled with superior levelling and durability. The amalgamation of both water based and solvent based paint properties caters not only to environmentally conscious users but also to existing customers who have grown accustomed to the use of solvent based paints. The paint industry continue to exhibit the trend of strong and continuous growth and its future is as unpredictable as it is exciting.
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Written by : Jonathan Quah