What Kind of Paint Seals Best?

Primers

• When it comes to painting traditional surfaces like walls inside a home, the best type of sealing paint is typically the primer. Primer is a light-colored paint layered on a surface to help prepare it for bonding to the important top coat. One of the jobs primer has is filling in the microscopic holes and cracks in the substrate. Because the primer will not be seen, it tends to be designed to seal more effectively than top coats.

Solvents

• Solvent sealants are based on powerful chemical compounds designed to resist many types of corrosion, and are famous for being removable only through the use of counter solvents. They set and cure very quickly, which can be a bonus for many painting projects. They are also flexible when it comes to temperature -- the ambient temperature of the room is generally adequate enough for them. The only problem with solvent sealers is that they shrink slightly as they dry, which could create small cracks at the edges of the sealant.

Oil and Plastic Paints

• When it comes to colored top coats, oil and plastic paints both perform better than water-based paint, which is too soluble in the presence of moisture to do well at sealing. But oil-based paints do not dissolve so easily and protect surfaces more easily from water. Plastic-based paints like acrylics and latex paints work even better. Latex paints are a common choice for house walls, and for good reason. Acrylics offer even better protection, but are more suited to smaller projects or unusual surfaces like concrete.

Substrate

• The type of seal the paint forms depends largely on the condition of the substrate. Even the best solvent coating will not be able to bond well with a rough, dirty surface. Clean and sanded surfaces will create the best paint seal. If any other seals are already installed on the surface, they should be removed before any new coats are added.