For porous substrates, like CMU, OSB or some sheathing products, two coats of PROSOCO R-Guard Cat 5 are necessary to achieve a pinhole-free surface. When trying to achieve the proper 12-15 wet mils of thickness on the wall with one coat, the weight and slower dry time of a heavier application allows the material to absorb into the substrate. While a heavier, single coat method may seem logical, it ultimately uses more material than needed and results in pin-holing, which means it must be recoated with a second application. 

When you use the recommended two-coat approach on porous substrates, we recommend the first coat be a thin coat, also known as a "kiss coat." This method saves money in material costs and labor with a faster application rate. The lighter "kiss coat," when applied first, dries more quickly and on the surface, shrinking the existing pores of the substrate. 

Then, a second coat is applied at a regular rate to provide a pinhole-free coating of Cat 5 for a properly functioning air and water barrier field coating. 

As always, we are here to answer any questions you have. Call us at 1-800-255-4255, Monday through Friday, 8 a.m.-5 p.m., Central Standard Time.