Cleaning
E
Southern Pine Council
xotic Woods
Pressure-washing decks can
be a great niche. But watch out
for shifting names and lookalikes.
By Diane M. Calabrese
or all the intrigue
evoked by the word
“exotic,” cleaning nonnative species of wood
is no different from
cleaning any other substrate: Know the
substrate, establish the goal, and then
find an environmentally compatible
method to get the job done.
The problem is the mysterious nature of certain exotic woods. The
names applied are not always scientifically accurate. Mahogany, for instance, has become a catchall moniker.
Therefore, any contractor who wants
to capitalize on the expanding market
of exotic woods must be able to identify species.
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JULY/AUGUST 2010
And the market is growing. “It’s definitely increasing,” says James Foley,
who owns Diamond Jim’s Pressure
Cleaning LLC, in Waterbury, Conn.
“Ever since problems with pressuretreated lumber, people have switched”
to exotics when possible.
Deck choices
The idea is that the natural constitution of some woods allows them to
withstand the vagaries of the environment, especially assault by insects. So
the hunt for tough species extends to
tropical forests, and names get muddled during harvest and transport.
Ipe, for example, has become “quite
popular in the last 10 years,” says Rick
Petry, owner of Windsor WoodCare in
Plainsboro, N.J. Hard, heavy and dense,
ipe can withstand the harshest outdoor
exposures—even sea spray.
The proportion of exotic woods
species used for exterior construction,
particularly decks, varies with geography. In the Garden State, Petry sees
about 65 percent pressure-treated
Southern Yellow Pine (SYP), 20 percent
cedar (primarily Western red cedar),
and 15 percent mahoganies (actually a
mix of species).
Along the shores of the Nutmeg
State, Foley sees decks that are largely
either exotic woods (on high-end
homes) or composites (on more affordable homes).
But ipe-type hardwoods also present a choice, Foley adds.
What’s in a name?
“Either they’re going to last a lifetime and turn gray,” beDefinitions of “exotic wood” often hinge more on prevacause stains do not penetrate and must be repeated. Or, if
lence than origin. “[In] the Midwest, you see a lot of cedar,”
no stain is used, “they have to be cleaned every other year.”
says Petry. “[On the] West Coast, you see a lot of redwood.”
However, when those woods are seen in other regions, they
Cleaning basics
may be considered exotic, so the term “is hazy at best.”
Cleaning prevents soil and spores from getting between
Instead of putting the emphasis on hardwoods from farwood fibers. That infiltration can set up conditions for a
flung places, it’s best to take each species on its merits. The
micro-community of organisms that can grow and comproimportance of determining the type of wood before devismise the wood’s integrity. Foley uses a solution of bleach
ing a cleaning method applies to all wood.
and surfactant with water.
Even treated SYP is not all the same, explains Petry, beCleaning will also brighten wood, says Petry. Again, the
cause the formula for treating the wood has changed over
choice is whether to just clean or to follow with a stain. For
the years.
example, if the decision with ipe is to stain it, “you’re going
Ipe is a popular choice for exotic decks in Northern Virto have to do it every year.”
ginia, says Steve Chapman, owner of Elite Pressure CleanAs for cleaning, it is a two-step process, explains Petry.
ing, in Bristow, Va. “We are seeing more [exotic woods] on
Sodium hydroxide or sodium bicarbonate is used, and then
higher-end homes. They’re gorgeous. The projects are recitric acid is applied to neutralize the basic solution. The
ally impressive.”
sodium bicarbonate or similar cleaning
The drawback for deck owners is that
agent is applied and then lightly
exotic woods require more frequent
washed off with water under low prescleaning and staining than do other
sure.
wood species. “The wood is so dense, no
The goal of wood maintenance is
stain will penetrate the wood and it grays
longevity. Graying may be an acceptreally quick,” Chapman says.
able aesthetic choice in hard woods
On the other hand, that’s good news for
like ipe. But less dense woods may be
contractors like Adrian B. Carrier, owner
vulnerable to warping if they are not
of ABC Pressure Washing & Deck Rescue
sealed. And those changes in shape, in
in Houston, who is cleaning more exotic
turn, can contribute to cracks, protruddecks than ever—partly because homeing nails and other safety issues.
owners have not maintained them.
“Some exotic species require re-sprays
every six months to maintain their
Speaking of species
beauty,” Carrier says. “We are also seeing
Sorting out the species of exotic
exotics with our other homeowners as
woods in a universal way is close to
well, due in part to renovations and folks
impossible. A few examples serve.
stevecoleccs
simply keeping their homes a little Always know the wood species before devising
Ironwood, ipe and mahogany are all
longer.”
common names that cut across taxoa cleaning method.
nomic groups established by botanists.
Ironwood is generally used to refer to the hornbeam plants
Washing warnings
in the genus Carpinus, but many deck builders call ipe an
So what is the role of using water under pressure to clean
ironwood. In doing so, they reference its strength ahead of
exotic woods?
its phylogenetic alliances.
“Pressure washing in and of itself is not harmful,” says
Ipe itself is Tabebuia impetiginosa, a species native to
Petry. “Some species like ipe can take a lot more pressure.”
Mexico and Argentina. Mahogany includes trees in the genCaution comes at the boundary between cleaning and reera Swietenia from the tropics of South America, Khaya
moving coatings. “Pressure itself shouldn’t be used to strip
from Africa, and Eucalyptus or Australian red mahogany.
wood,” says Petry.
Such confusion is reason enough for contractors to emNotes Foley: “What you’re getting rid of [with power
phasize to customers the importance of buying wood that is
washing is] dirt and pollen.” Washing hardwood like ipe
certified as a particular species. Do not recommend wood
with pressure between 500 and 1,000 PSI is fine. Then,
light oil can be applied.
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When the Pressure is On
Cleaning and sealing pressure-treated wood takes a special touch.
By Brett Martin
Pressure-treated wood has been
its environment and sometimes
a favorite for outdoor projects for
can reposition itself due to the
generations. Infused with preservaloose grip of the hardware used,”
tives under pressure, P.T. wood can
he says. “It is not uncommon to rewithstand moisture, decay and
place nails or screws either due to
ground contact for years.
rust or grip failure. I generally use
Although pressure-treated wood
galvanized wood screws as it recontaining Chromated Copper Arpels rust and premature aging.”
senate (CCA) is no longer being proThe best finish for pressureduced for use in most residential
treated decks offers ultraviolet
settings, much of it is still out there.
(UV) protection, repels water, and
Whatever the preservative, presstops mildew growth. Applying
joebrandt penetrating stains to CCA-treated
sure-treated wood requires a difPressure treated wood is still popular for its ability to resist
ferent approach than untreated water and mold.
decks at least once a year may
wood.
even reduce potential exposure to
Washing with low water pressure and then using a penetratarsenic, the U.S. Environmental Protection Agency has said.
ing finish are the keys to maintaining a pressure-treated wood
Stains and sealers may be water- or oil-based. Each has
deck.
pluses and minuses, and even these may be in the eye of the
“You really don’t want to use high pressure, because once you
beholder, depending on your priorities. Oil-based products gendamage the wood, you have another problem to deal with,” says
erally penetrate deeper, give a richer color, and last longer. But
Colin McCown, executive vice president of the American Wood
the oils typically are also harder to work with, harder to clean
Protection Association (AWPA) in Birmingham, Ala.
up, less environmentally friendly, and take longer to cure.
Adrian B. Carrier, owner of ABC Pressure Washing & Deck
Moreover, each product is unique, and even the same prodRescue in Houston, recommends no more
uct can perform differently under different
than 600 to 800 psi of water pressure to reconditions, depending on climate, wear,
move mold, algae and the old finish.
moisture and other factors. In the end, your
Finishes for
“Let your strippers and cleaning solutions
best bet is to talk to the manufacturer’s rep,
do the work for you,” he says. “High pressure pressure-treated
store reps and other contractors about a
only damages the wood and guarantees that
product. Remember to read the entire label
your next step will be the rental or purchase of
decks should have before you start the job.
a walk-behind sander before applying your
And, the pros say, avoid paint, since it forms
finish.”
a film over the wood.
UV protection,
Steve Chapman, owner of Elite Pressure
“I wouldn’t recommend a solid paint over
Cleaning in Bristow, Va., uses a bleach-free
P.T. wood, as it will not allow the wood to
repel water and
brightener and low water pressure to prep the
breathe and will dry it out, causing premawood.
ture cracking and warping,” Carrier says.
“After pressure washing, I use carbide inhibit mold growth. “Oil will keep a soft wood soft. Semi-trans
brushes to remove loose, soft fibers,” he says.
or semi-solid oil finishes will also allow you
“That’ll make the stain last longer.”
to see the beauty of the wood grains.”
Because pressure-treated wood is a softwood, Carrier reBrett Martin has worked in the construction and remodeling
sinks nails and screws in the deck. “Being so soft, it ‘gives’ with
industries. Contact him at dee-brett@msn.com.
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JULY/AUGUST 2010
CLEANING from page 23
that cannot be verified by species and supported by proper
import permits.
Nor should you rely exclusively on architectural specifications to identify wood, says Foley. The specs can be misleading, because of the generic use of names for wood
species.
Difficult jobs
As noted previously, water under pressure should not be
used to remove coatings. Removal is typically a job for mechanical devices. Foley, for example, uses a tungsten carbide abrading machine.
On the other hand, mistakes by one contractor can lead to
a good contract for another who can step in and fix the problem. Foley has been taking care of red cedar doors in a
multi-dwelling residence since he was able to go in and correct another contractor’s error. (“It all happened because
they put the finish on too soon.”)
Resolving issues for customers is gratifying, says Foley.
Figuring out what the wood is and how to care for it is professionally satisfying and typically leads to long-term maintenance contracts.
Petry, too, thrives on resolving problems. A few years ago,
for example, he was called on to deal with natural redwood—a rarity, since most redwood used in decks now
comes from plantations.
“The redwood was 24 years old,” says Petry. “It was just
loaded with its own resins.” Those resins, combined with a
sealer recommended for redwood, had turned the color
black.
The lesson, say Petry and other contractors: Testing first
is a must, for coatings and pressure settings alike. For example, Port Orford cedar that comes out of Canada is relatively soft but can take the pressure, says Foley. (Port Orford
cedar, Chamaecyparis lawsoniana, is also known as Oregon
cedar and Lawson cedar.)
Mahogany and cambara (Erisma uncinatum) are “easier
to take care of as they age,” says Foley. “They open up more,
and product can go into them.” At the same time, some alkali finishes are not suitable for those types of wood, because they get in too deep.
Minding the details
To keep all of this straight, record keeping is essential.
Foley keeps a portfolio of photos to show customers what
they can expect.
Petry used to carry wood samples to show customers.
Now, he also uses photos.
Developing experience with, and a systematic approach
to, exotic woods can make contractors experts beyond the
traditional spheres of cleaning and maintenance.
For example, customers now ask Foley to recommend
what wood to use in deck replacements and new construction.
“You really get to know exotic wood when you’ve done it
a few times,” he says.
Adapted with permission from Cleaner Times: The Journal for High Pressure Water Applications (Vol. 20, No. 5).
Brett Martin also contributed to this article. pwc
General advice
It is important to understand that “exotic wood degrades
differently,” says Foley. “The first finish is the most important.”
“You’re stripping a lot in the beginning,” he says. Then,
after the wood is fortified to resist invasion of particles and
organisms, the key becomes the contractor’s knowledge of
coatings.
“As far as cleaning exotic woods, it has to do with understanding sealers,” says Foley. That means more than following manufacturers’ instructions. It also demands keeping
careful track of results and making adjustments as necessary.
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