Improved Weatherability of Outdoor Wood Stains Using NanoTechnology

By Roger H. Cayton, Patrick G. Murray, David Nelson, Ryan Ostrowski

There is no question that vast amounts of time, research effort, and capital have been invested in nanotechnology in general over the past 20 years. The majority of this effort has been expended by government laboratories, academia, and industry, and a diversity of new nanomaterials, new routes to nano-versions of existing materials, and improved metrology and analytics have emerged as a consequence. Indeed, hundreds of tons of nanoparticulate zinc oxide and titanium dioxide are sold into topical human sunscreens and daily wear cosmetics every year.

That the benefits these materials (particularly zinc oxide) bring to sunscreens and cosmetics might be useful in other areas which require UV protection, such as coatings for outdoor wood, seems obvious. Despite this, commercial adoption of these materials for UV protection in exterior coatings has been less rapid than some forecasts had originally suggested it might be, despite well-known deficiencies in the existing organic UV absorbers.

In fact, in many instances, innovative stain and finish developers investigated powders or newly developed dispersions of UV-absorbing metal oxides such as zinc oxide, titania, or ceria and discovered that the promised value (high performance, transparency) simply did not exist. It appears that assumptions about “drop in” performance in the end-use applications for nanoparticle containing additives may have simply been too optimistic. Why is this?