Oil- or water-based exterior wood coating?

The production of a usable coating, whether it is to be applied indoors or outdoors, requires the dissolution of its components in a liquefying agent. The manufacturer's choice of agent enables the familiar classification of coatings as 'water-based' or 'solvent-based'. While the latter term is a catch-all which extends across a wide range of organic (oil-based) liquids, the basic distinction holds good.

The last couple of decades have seen a general shift away from solvent-based finishes, especially in the DIY sector, where convenience tends to outweigh all other considerations. However, a professional determining an appropriate finish for an external wood coating may want to take a broader view.

Here are the deliberations which Redwood customers have shared with us while making their choices. We hope they'll help you reach your own decision.

Quality and appearance

Many pros feel that the viscosity of a solvent-based finish enables better coverage of joints and fissures. This may lend a more attractive appearance to a job, besides making it less susceptible to temperature and humidity variations during the curing phase. (Many a water-based external paint job has been compromised by an air conditioning unit spurting 'HVAC fog'.) It's also important to note that getting optimum results from a water-based finish may require modifications to time-honoured surface preparation and brush techniques.

VOC concerns