Domestically Sourced,
Thermally Modified Ash
Dimensionally stable, sustainable, highly
durable, and ideal for outdoor use.
Thermally modified ash adds a domestically sourced species to our
offering. Highly
durable, modified ash is a perfect material for outdoor furnishings, as it has a long
lifespan, is low maintenance, and ages slowly and beautifully. Modified ash retains its
uniform grain character and takes on a deep brown color that grays over time.
The
eco-friendly, low-impact modification process uses heat, not
chemicals, to alter
the chemistry of the wood, making it resistant to environmental elements, including
insects, moisture, and the warping, cupping, expansion, and contraction moisture
causes.
Thermal modification also reclaims ash species that have been affected
by the
Emerald Ash Borer, putting the trees to productive use in an outdoor environment
instead of burning or landfilling them. Approximately 40 percent of the ash we
thermally modify has been affected.
The Weathering of Wood —
A Natural Process
Weathering is the general term used to
describe the physical change materials exhibit
with exposure to the outside elements..
Materials may encounter moisture, sunlight,
heat/cold, chemicals, abrasion, etc.—all factors
in the natural weathering process. The natural
wood options that Landscape Forms offers
will maintain their structural integrity and resist
rotting for many years without any kind of
treatment. They will, however, exhibit signs
of natural weathering, which include graying,
checking and tannin leaching (Jarrah only):
Weathering
Graying
Unfinished wood will weather to a natural gray patina.
Checking
During the initial drying process the outside of the wood dries quicker than the
interior, which causes differential stresses to develop. The combined effect of these
drying stresses in wood often results in the formation of a check or a split.
These seasoning characteristics are not problematic; it is important to remember
that as wood dries, it becomes stronger. The development of these seasoning
characteristics is quite normal.
Tannin Leaching (Jarrah only)
Tannins are natural organic compounds present in certain timbers; leaching of tannins
can cause discoloration on surrounding materials. Tannin leaching commonly occurs
when certain timber are exposed to rain or other sources of water (e.g. sprinklers.)
This leaching process only occurs for a short period of time while the wood naturally
weathers in its outdoor environment.
(Tannin bleed is unlikely in thermally modified woods as the tannins are naturally
removed during the thermal modification process.)
Natural Graying of Wood
Ipe
Jarrah
Domestically Sourced Thermally Modified Ash
Finishes Not Recommended
Wood Finishes
Finishes applied in an attempt to maintain the new color of wood are not
recommended. No wood finish is weather-proof; most finishes are weather resistant
for a period of time but require ongoing maintenance. Finishes like exterior varnish or
polyurethane will break down in the outdoor elements. The addition of UV inhibitors
will delay the deterioration of the finish but will not stop this deterioration completely.
Seasonal expansion and contraction will rupture the finish and expose the wood
beneath creating an unattractive surface condition.
Oil Finishes
Other materials used to finish outdoor woods such as wood penetrating oils will
penetrate the wood and highlight the grain and natural color of wood. However, these
oils will not harden; the solvents will evaporate leaving the wood to weather with oil
residue in the pores. With annual maintenance this may be acceptable for decking,
however, this is not a recommended treatment for site furniture where oils and
attracted dusts may rub off and stain clothing.
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