There are innumerable deck sealants available, most of which do an effective job of sealing and protecting wooden surfaces, and they fall into two major categories: oil-based … and water-based sealants, usually acrylics. As a general rule, oil-based sealants can last 1-2 years longer than water-based sealants (acrylics), but acrylics are more environmentally friendly and require a much easier clean up.
Oil-based sealants soak into the surface and slowly wear away, for a rich, natural look, requiring no removal process (STRIPPING) between applications. The thinner the oil particles (low viscosity), the more deeply they can penetrate, so lowest viscosity sealants that penetrate deeper and last longer are always more expensive.
Acrylic sealants have a uniformly painted look, masking flaws very well and allowing creative color options, but are high-maintenance. They form a layer on top of the surface instead of soaking in, which often wears unevenly and requires occasional touch-ups, often monthly after the first year. Acrylic sealant remaining from previous applications must be removed (STRIPPED) prior to resealing the surfaces.
These GENERAL rules were augmented in 2009, when new EPA standards forced sealant formulas to change drastically to capture the benefits of an oil-base, while still conforming to these standards.
The EPA ordered that, as of July 1st, 2009, lower VOC (Volatile Organic Compound) limits will be in effect within the state of Illinois. Under these regulations, oil-based products (which have naturally higher VOC levels than acrylics) can no longer be applied or sold in Illinois, unless reformulated to meet these new standards.