We used the Novawood thermally modified wood decking and did an exposure test that ran 4 months beginning at December 1 st, 2015 and ran until April 1st, 2016. The thermally treated wood was not treated with anything and was simply washed down with soap and water when the testing was initiated.
As you can see the wood sample on the left turned a silver patina grey color and was consistently the same patina grey color through out the piece. The sample on the right was treated with two coats of Cutek Extreme Wood Preservative in a clear coating (no color tints).
The testing revealed that thermally modified wood will grey out at a fairly rapid pace if not treated at all. It will however remain very structurally sound and stable. The samples were tested for deviations in length and width and the deviation was within a 1/8″ of original measurements.
The thermally modified wood species that was used in the test was North American Ash.