What Makes Paint Dry
Pivotal to its application, the drying mechanism of paint tells us much about its formulation.
The majority of paints dry through evaporation, a process that allows its pigmentation to be set onto a chosen surface purely by being exposed to the surrounding atmosphere. However, the drying process can vary and is often complicated and altered between different paint types.
Paints usually contain three key components: pigments, binders and additives. Pigments are dry, insoluble powders that by wave length-selective absorption (ie they only reflect certain wavelengths) change the colour of reflected or transmitted light, giving paint its colorization. They can be ascertained either naturally or produced synthetically.
The pigments of paint are given their paint structure by binders, synthetic or natural resins such as acrylics, polyesters or oils that impart adhesion and influence durability and flexibility. Crucially, though, binders can also play a role in how paint dries, curing it as well as supplying it with adhesion.
It is important to note that curing is a different process to drying – which, as mentioned before, is caused by evaporation of a solvent – with cure adhesion attained by polymerisation (molecules bonding together in a chemical reaction). Binders are arguably the key component of paint, as without them it would never stick to a surface long enough to dry.
Finally, paint additives help to conjoin the other components and aid application, structure and drying. Certain additives are often used as catalysts for polymerisation, while others are included to prevent the clumping of paint or in order to alter its viscosity.