We have
some articles that will help you get the most out of your wood
furniture.
BEHAVIOR
OF WOOD
Any
article of wood is subject to warping due to changes in humidity.
Although special care is taken at every step of the manufacturing
process—starting with the finest wood available—special
care should also be taken to prevent problems with reproductions
in your home.
Remember,
you can't fool Mother Nature. Wood is a hygrosopic material,
which means it tends to give off its moisture to a dry atmosphere
or take on moisture from a damp atmosphere until an equilibrium
between the two is established. In fact, with unfinished oak
reproductions, for example, a dimensional change of approximately
one percent may occur with each three percent change in the
moisture content of the wood. This applies to hardwood more
than softwood and with oak being one of the hardest of the hardwoods
the actions and changes are more defined.
Air
always holds varying amounts of moisture at different temperatures
and the term relative humidity expresses what percentage of
water is actually being held by the air. Warm air can hold a
great deal more moisture than cold air. For example, if we take
a sample of air at 32 degrees and 10 percent humidity and heat
it to 75 degrees, its relative humidity will drop 20 percent.
Thus we can easily see that heating the air will lower the relative
humidity appreciably.
Based
on the simple scientific principles, it can be easily understood
how changes in relative humidity may adversely affect your reproductions.
During
the colder seasons of the year, outside air—which can hold
little moisture—enters the room and is heated to room temperature.
As the air is heated its relative humidity becomes even lower.
Additional moisture is needed at the higher temperature so this
moisture must be supplied from items in the room. Wooden articles
(since they are hygroscopicin in nature) are good suppliers
of moisture to the dry, thirsty air. Oak tables, for example,
with their large expanses of wood, are particularly susceptible
to being a provider of moisture.
In
giving off the moisture to the air, the moisture content of
the wood is lowered and a shrinking and drying action occurs.
This shrinking—if sever enough—can be observed by
checking (small cracks), splitting and warping.
Raising
the relative humidity may reverse that procedure and cause wood
to swell, sometimes closing cracks and splits.
No
matter how thoroughly lumber is seasoned, preshrunk or finished,
some shrinking and swelling of the finished product is inevitable
because canstant atmospheric conditions seldom exist in the
home. Again, wood is hygroscopic and responds to changes in
relative humidity so its moisture content is constantly changing.
Once
our reproductions are placed in the home, the wood in them generally
reaches an average moisture content and changes in relative
humidity cause fluctutions above ths average. These changes
in moisture content do not follow immediately after the cahnges
in atmospheric conditions due to the effectiveness of the finish
as a moisture barrier. But even the best finishes are not 100
percent effective and they will eventually allow the wood to
reach an equilibrium with the air if conditions are maintained
over a long period of time.
Since
relative humidity is the most important factor in keeping reproductions
in good condition, every effort should be made to maintain a
relative humidity between 35 and 45 percent whenever possible
during the heating season. Room humidifiers are inexpensive
and effective, but heating system humidifiers are more effective
for keeping large areas at a comfortable relative humidity—comfortable
for both the wood and the people who live at the home.
Remember,
unit heaters are particularly harmful to wood, because they
blow hot, dry air on to the surface only. Sudden changes in
temperature and extremely hot, dry air can easily cause warping
and cracking. Exposure of reproductions to direct sunlight may
also cause similar damage.
Becasue
the wood is a "living" material, it tends to "breathe"
with changes in the humidity of the air. As the air around the
table becomes dry (as in a heated building on a cold day) the
wood will tend to dry out and shrink as it comes into equilibrium
with its environment. On a warm, humid day the opposite will
happen and the wood will swell. These changes are normal and
should be regarded as part of the natural variety and beauty
of solid wood furniture.
Careful
choices of cleaning supplies can also reduce damage to wooden
surfaces. A feather duster or a soft brush is useful for cleaning
wood, and a dustcloth made of fabric with a soft nap will reduce
the amount of abrasion on polished surfaces. Most commercially
available products are also an effective way to keep your solid
wood furniture looking its best.
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