First Guide to Asphalt Sealer Test Results
We didn’t think we needed to. In general we thought asphalt-based products neatly fit into a category with low concentrations of toxins called polycyclic aromatic hydrocarbons or “PAHs.” Coal tar sealers on the other hand, exceeded those concentrations by a thousand times, so it wasn’t that important to differentiate between the non-coal tar products.
Now We Need a Guide
In 2015 a new line of non-coal tar products was introduced which challenged that thinking. We wrote about it in an article entitled, “New Sealer Alternatives Aren’t All They’re Cracked Up to Be.”
Initial tests and product literature indicated these new products have PAH concentrations more akin to coal tar than asphalt. The comparison figure below illustrates this point. The height of known structures can be compared to the concentrations of products. Before, most asphalt-based products were in the range of a small dollhouse with low concentration of PAH’s and coal tar products loomed tall with large concentrations like the One World Trade Center depicted.
Re-examination of Existing Products
That is why when this first came to light, we asked (December 2015) the industry to step forward and have your products tested.
What the Testing Doesn’t Reveal
What the Testing Does Reveal
Apples to Apples Comparisons
decrease in PAH levels during drying. How this would affect HPO sealers is uncertain but could have a similar effect. All figures have been adjusted to reflect a dry weight basis, but there has been no allowance for the loss of PAH’s during drying and its effects.