The Zero VOC myth – why all paint emits fumes
VOC emissions are intrinsic to paints and painting.
Even many chemists are not fully aware of this surprising principle, but expert polymerization specialists, such as Monona Rossol, give this advice to anyone involved in paint.
VOC emissions are a natural product or by-product of paint curing and polymerization in the same way as the production of saw dust is intrinsic to using a saw in woodworking.
This fact holds true, regardless of the chemistry or composition of the paint binder agents. Of course, some paint products and binders have very low emissions and are of lesser concern, while other formulations contain up to 50% of toxic thinners such as mineral spirits, and these may present immediate and long term danger to health (for example, working in a small solvent filled room while painting with say gloss paint and spirits can overwhelm the lungs and heart and cause death).
This explains why even paint formulations with very little solvent content (these do exist, and should be used if possible!) always require a degree of ventilation and protection, both for health and for full polymerization and paint hardening.
Manufacturers can only make claims such as ‘Zero VOC’ because their product may contain VOC amounts smaller than what is required to be declared by law. (For instance: below 1%). Tests showed that in over 25% of cases VOC content may actually be much higher than what has been declared by the paint company, so even sds sheets can be a poor and insufficient guide for user safety.
In terms of workers health this is very significant, as many known VOCs and SVOCs — semi volatile organic compounds — are carcinogenic or neurotoxic even at very low concentrations (for instance benzene, styrene, quinones, vinyl chloride, naphtha, or butadiene).
All types of ‘plastic paint’, ‘polymer paint’, ‘acrylic paint’ or ’latex paint’ etc. contain complex mixtures of such solvents that are hidden inside nano-scale ‘balloons’ or ‘monomer – miscelles’; (and these become activated and partially airborne, as heavy mists when the paint begins to dry).
Many types of oil paint are made from binders that truly are VOC free at the time of painting. For example, drying oils such as linseed oil are initially VOC free.
However, within hours of paint application a slow oxygen consuming redox reaction begins which by itself then starts producing and emitting a range of common VOCs such as formaldehyde, acetaldehyde, benzene, ketones, mineral spirits, and so on, and due to these emissions linseed oil paint may even become flammable and can self-ignite when activated.
Again, ventilation and airflow are always needed to create a VOC free working environment, and to facilitate paint curing. In the case of oil paints this process can take several weeks, until emissions stop.
acknowledgement: many thanks to Monona Rossol for her invaluable expert advice on safety, chemistry, and VOC polymerization reaction products