The Paint Quality Institute Welcomes Dr. Stewart Williams to its team!

New Technical Director Brings Vast Experience to PQI

Following the retirement of John Stauffer, The Rohm and Haas Paint Quality Institute is pleased to announce the Appointment of Dr. Stewart O. Williams as Technical Director.

The Rohm and Haas Paint Quality Institute is happy to announce the appointment of Stewart Williams, Ph.D. as its new technical director. Stewart succeeds John Stauffer who served the painting and specifier community so well for many years.
Stewart brings a wealth of paint industry experience to his role with PQI. After joining Rohm and Haas in 1989, Stewart served in key technical and business roles, including coatings application research, technical management, and global coatings management. He led business efforts as market manager for the company’s new construction segment and has extensive experience formulating quality paints and coatings. But perhaps Stewart’s greatest strength is his warm personality and his ability to interact and communicate with people—a talent that will serve him well in his interactions with painting contractors, paint specifiers, and paint sales personnel.

Among his many new responsibilities, Stewart will develop and implement training initiatives for professional painters and paint sales personnel; manage the technical content of paintquality.com, and conduct seminars about quality painting. Stewart is also available to journalists, providing his technical insights to painting and home improvement.

Stewart holds a Bachelor of Science degree in Chemistry with Physics from the University of the Virgin Islands and a Ph.D. in Physical Chemistry from the University of Washington.

Contractor Education - Q&A

Q: From time to time we have to do staining. When should I consider a semi-transparent vs. a solid or opaque stain?

A: This depends very much on the desired look or appearance you want and on durability you want. To see the natural grain structure of the wood you should chose a semitransparent stain. Semitransparent stains have a thinner consistency and use less pigment. Solid color stains have a higher pigment content (more consistent with paint). As a result solid color stains go on thicker, and generally last longer than semitransparent stains. Top quality semitransparent stains usually last a minimum of 3 years while solid color stains last a minimum of 5 years before needing re-staining.

Q: I have recently installed a new deck, when is the best time to stain it?

A: This depends on several factors. If your deck is made of composite wood then tests done at the Paint Quality Institute show that it is best to let the deck weather for a few months prior to staining. We believe this allows processing aids used in manufacturing the composite material to weather away leaving a substrate that is easier to adhere to and better accepts stain. We strongly recommend that you review the manufacturer’s recommendations prior to staining. If your deck is made from natural wood, then we recommend you stain as soon as possible since the weathering process begins immediately on installation. Some woods, such as cedar, can begin ‘greying’ sooner than other woods and should be stained immediately.

Q: Can you put a waterbased acrylic stain over an aged solvent borne stained deck?

A: Yes! There are a couple of important steps, preparation and selecting a good quality stain, that impact the relative success of the job. If the goal is to apply a semitransparent stain (and hence see the grain structure in the wood) then it is important to expose the wood – therefore, all remaining stain must be removed. Appropriate stripping material should be used where stain remains and all loose debris (including loosely adhering stain) and mildew should be removed. Depending on the level of weathering and surface degradation in the wood then it is advisable to use a wood conditioner prior to applying a waterbased stain. A top quality waterbased acrylic latex stain would deliver a good final finish and durability provided the surface preparation is done adequately. In the case of a solid color stain, this is analogous to the well accepted practice of applying a waterbase acrylic paint to the exterior of a house. No significant issues should be anticipated provided a top quality stain is chosen. In fact, most solid color stains sold today are based on waterbased acrylic resins. Just as in conventional exterior applications, these acrylic based solid color stains deliver maximum durability and excellent clean-up.

Q: Why should I consider painting my composite deck?

A: Composite decks contain wood fibers and just like natural wood, they are susceptible to UV degradation. While progress has been made in making composite wood more weather resistant, composite wood can still show a tendency to fade or show mildew with time. A good solid color stain can help to enliven the composite deck with performance that would last a time. Unlike natural woods, it is recommended that you allow some natural weathering (minimum of 3 months) prior to staining to ensure adequate adhesion. We strongly suggest that you consult with the manufacturers recommendations prior to staining.

Q: Is priming recommended when applying solid color stain to wood?

A: As with any paint job, a good primer helps to guarantee a better finish. A good primer helps to tie the top coat to the substrate. A good primer is engineered to deliver good adhesion and stain blocking resistance. PQI recommends the use of a primer or two coats of a 100% acrylic solid color stain to deliver acceptable durability.