In the area of paint we speak indistinctly solvent and thinners, both are chemicals compounds that are added to the paint but with different functions and objectives, then what is the difference between solvents and thinners?
Solvents are defined as chemicals compound that are introduced during manufacture of the paint itself and before packaging, in order to maintain all components of the paint (resin, pigment, additives ...) in a liquid / viscous state such as we know it.
Thinners are defined as chemical compounds that are introduced into the paint prior to application, in order to modify the viscosity and other properties related to the rate of curing that may affect the functionality and aesthetics of the final layer painting.
In response to the above definitions, both solvents as thinners are chemical compounds with low molecular weight even be the same compound, but the difference is the function for which are designed and at which the moment that they are added. Solvents dissolve the paint before packaging; thinners diluted the paint before applying.
The concept of dissolve and dilute we will understand better with the following example, imagine we have a glass of chocolate into small pieces, if we add hot milk chocolate dissolve transforming from a solid to a liquid state, if you later add more hot milk dilute liquid chocolate decreasing its viscosity, ie we make it fluid. In this example the hot milk acts as both solvent and thinner.
In painting, as in the previous example, the chemical compound used as solvent can be the same act as a thinner, but in many cases the thinner is different to the solvent used during its manufacturing process, in the latter case the thinner must be fully compatible with the solvent which incorporates painting.
Requirements of the solvents:
Solubilize the resin backbone of the paint, in order to obtain the paint in a viscous liquid state.
Must be volatile under the conditions that forms the paint film, ie, once the process begins drying / curing of the paint have to evaporate the solvent so as not to form part of the dry paint.
Factors affecting the selection of solvents:
Power solubility or solvency
Requirements of the thinners:
Must be compatible with the solvents contained in the paint itself.
Must be volatile under the conditions that form the paint film, ie once you start the process of drying / curing of paint thinners must evaporate in order to not be part of the dried paint.
Functions of the thinners:
Adjust the viscosity of paint depending on the application method and the paint used (roller application, gun spray, paints with high solids contents)
Control and regulate the drying time and evaporation (slow thinners in summer and fast thinners in winter) and thus prevent functional and aesthetic problems (boiled, loss of gloss...)
Solvents, safety and the environment.
Solvents such as thinners, need evaporate during drying / curing of the paint in order not form part of the dry film, this evaporation produce in the ambient a concentration of chemicals (VOCs – Volatile Organic Compounds) negatively affect both the environment and the health of people who are exposed.
For that reason, the painter who uses this type of paint must be protected via respiratory masks, gloves, goggles ... of adverse effects that can produce solvents and thinners.
Regarding the environmental issue and in order to reduce the concentration of VOCs it must be used activated carbon filters, ozone generators, burners of VOCs ...
Due degree of health and environmental hazard representing intensive solvent paints, countries are being put into practice laws that lead to the use of paints containing no solvents or thinners necessary use.
Due this need the paint industry has developed alternatives as high solids paints, powder paints or water-based paints in which the thinner and paint solvent is water.
Now that you know the difference between solvents and thinners, did you know that one way to reduce the viscosity of the paint is pre-heating?, So use less thinner saving in both cost and environmental health problems.
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