|
 Often
in the wood powder-coating business an old adage rings true:
“You get what you pay for.”
If a company invests in quality — from state-of-the-art CNC
machinery and powder-coating equipment to skilled technicians
while using only the highest quality medium density fiberboard
and powders — the final product is going to yield a very high
level of durability, dependability and aesthetics that
produces an excellent finish compared to other surface
treatments.
If any one of these steps is neglected along the way, if a
company doesn’t invest in state-of-the-art technology,
personnel and materials, quality will suffer and the final
product just won’t make a good impression on the customer or
end user. Some of the photos shown here do not necessarily
represent wood powder-coated materials, but rather they
illustrate possible
 applications of
powder coated wood.
But how is quality measured, especially when the naked eye
cannot always detect it? Can you be assured a beautiful wood
powdercoated finish is going to hold up to such elements as
human abuse, environment — hot, cold, moisture and dampness —
or otherwise? In the wood powder-coating business, which is a
relatively new technology, quality control does make all the
difference, and quality in really does equal quality out. For
wood powder coating, the attention required in creating the
highest quality finishes requires substantial investment in
many elements, such as:
1. State-of- the-art technology and equipment;
2. Premium materials custom designed and cut to meet
specifications;
3. Technical expertise combined with skilled craftsmanship;
4. Documented processes for quality and QC testing
methodology.
The above steps must be taken into consideration; if not, the
manufacturing process can easily jeopardize the quality of the
piece.
Unfortunately, all too often wood powder coating is produced
by companies lacking in one or all four of the above process
steps, and the potential is great for a really bad experience
for the customer. The end product may not look good or meet
the performance specifications desired, such as moisture
resistance, abrasion and impact resistance, chemical and stain
resistance. It should be noted that if a product is not fully
cured, then many of the durability traits desired will not be
met, which defeats one of the main purposes in using wood
powder coating.
 State-of-the-art technology is
essential
Quality requires a major investment in technology and know-how
to ensure the integrity of each and every component, no matter
the size or intricacies of product shape. It is critical to
use ISO 9000 type processes and procedures to assure
consistent quality and documentation.
Using state-of-the-art powder-coating equipment, custom
designed for wood powder coating as opposed to using equipment
that was designed to powder coat metal, is essential. A
quality finish in metal powder coating does not vary much from
one coater to another. Whereas, with wood powder coating,
which is more complex, the quality varies so greatly that in
the past poor workmanship by some practitioners has given wood
powder coating a bad image with respect to appearance and
meeting performance specifications.
For example, a powder-coat system with eight automatic guns
will not provide as uniform of a high-quality finish as a
15-automatic gun system will produce. More guns creates a more
consistent finish and mil thickness with better powder
transfer efficiency, resulting in the desired high-quality
finish, especially with larger parts. Typically, fewer guns
produce streaking (tiger striping) and an inconsistent and
inferior finish; the lack of consistent mil thickness will
result in poor moisture resistance.
Powder application systems should have the ability to reclaim
powder for maximum cost efficiencies, and quick color change
in the manufacturing process saves time and money. It is
imperative the powder system is in an environmental room to
control temperature, humidity and contamination from dust and
dirt. As the parts move along the conveyor system right after
the final cure oven, it is important to have a cool-down room
to reduce board temperatures for final packaging and a higher
quality finish.
Finally, a critical process step is to have the proper wood
CNC equipment for machining parts, as board preparation is
essential to a great finish. It is also important to coat the
parts within a short period after the machining process
because of the porous nature of MDF when cut — it will
actually start drying out the cut pieces.
Premium powders and MDF
It is important to use the premium quality resins and powders
that are custom formulated to the desired performance
specifications such as moisture resistance, abrasion and
impact resistance, chemical and stain resistance, color and
finish matches, and UV protection. Certainly not all powders
have the same performance characteristics, so it is important
to work with an expert to best meet the customer’s needs.
Different powder formulations produce different results,
whether it’s a textured, gloss or smooth finish and custom
colors including PMS/RAL colors, multicolored powders, veined,
granites or just custom formulated to match color swatches.
The quality of MDF varies greatly, and it is essential in the
process chain along with powder choice. It is critical to use
only one of the top two brands on the market. This premium
grade MDF is specially formulated for wood powder coating to
ensure proper moisture content, density and minimize fuzzy
surfaces after CNC cutting. It also offers the benefit of
being very green friendly with 100 percent recycled content.
Plus, it is currently being reformulated, so in the future
there will be no formaldehyde additives.
Marriage of craftsmanship and
technicians
Quality is only as good as the people who control the process.
Although much of the wood powder-coating process is automated,
the finished product is really in the hands of the experts who
cut and prep the MDF and the technicians who control the
powder application technology. Training is imperative so that
each member of the team understands the wood-coating process
and their role in creating a quality finished product.
It is a marriage between the old world skilled craftsmanship
of the past with the computer technology of the future — this
process joins these two very different approaches into one.
Performance specifications and
testing for quality
Wood powder coating has its subtleties, which only experts
working with this technology will understand. While streaking,
blotchiness and roughness are obvious to the layman, other
predicators of quality are not visually seen with the naked
eye.
It is important to use the proper powder formulations while
using resins such as: epoxy, polyester, acrylics and various
combinations with each custom formulation designed to meet the
unique performance characteristics desired. Testing for
quality is tied directly into the customer’s specifications in
the powder formulations used. It is crucial to formulate the
powder application individually for each specific application,
then manufacture to the highest quality level to meet those
specifications and customer satisfaction.
1 Visual
inspection: This is typically done to meet different
customer requirements given that some customers prefer
flawless perfection and others require from a distance of an
arm’s length to see few, if any, imperfections. There is a
wide range of criteria ranging from specs, size of specs,
number of specs per square feet, blemishes, etc. It is
important that all parties clearly understand the expectations
so there are no misunderstandings and defects can be pulled
from production runs.
2 Mil thickness:
Mil thickness is the ultimate test for quality and durability
since MDF can be less stable and more difficult to control
when compared to metal; therefore, an even mil thickness
application is critical. For optimal results the thickness
should range between 3 to 9 mil, depending
on surface. Typically the thicker the mil coverage, the more
durable the finish, so on horizontal countertop surfaces we
apply thicker mil coverage for greatest durability. Mil
thickness should always be within ±1, and this level can’t be
determined just by looking at it; so it is important to use
the right equipment, fine-tuned processes and testing methods
and procedures. At BTD Wood Powder Coating, we randomly pull
sample parts (based on a percentage of plant production) and
test mil thickness with a Tooke gauge, ensuring that powder
application meets manufacturing specifications.
3 MEK Rub Test:
Surfaces are subjected to 50 double rubs to guarantee that the
powder has been fully cured and won’t rub off. There s hould
be little transfer of color to the swab tip; if there is, the
powder is probably not fully cured. A properly cured finish
also ensures the surface’s resistance to abrasion, water and
chemicals. For the best results, use an applicator with a
wooden shaft as MEK will deteriorate plastic and paper shafts
rapidly.
 4
Moisture resistance: This test can range from a
quarter size drop of water left on a part for 24 hours to
total part submersion in water for an extended period of time.
Plus, there are moisture and temperature chambers for conduct
testing the combination of hot/cold with humidity.
5 Chemical and stain
resistance: This consists of exposing production samples
to various chemicals and products, such as mustard, grape
juice, etc. for a period of time to determine the powder and
applications ability to meet the customer’s determined
specifications.
6 Impact and abrasion
resistance testing: This testing is usually performed
using testing methods and devices called Taber Abrasion,
Pencil Hardness and Hoffman Scratch Resistance. It sounds
quite basic, but the hammer test provides a good test of the
powder’s adhesion and the surface’s durability. If a hammer
blow chips the surface, then adhesion is obviously poor and
the finish is of very low quality.
7 Adhesion test:
Although a high-quality wood powder-coated surface will resist
scratching and cutting, surface adhesion can be tested by
cutting crosshatches (using industrial cutters) into the
finish. A strong adhesive tape is applied to the cross hatch
cut into the surface with a razor blade, then pulled. The
adhesion of the coating is
rated on its ability to resist removal from the substrate.
Ideally, there should be no visible signs of the paint on the
tape, and the wood should pull off with
the paint on the tape.
8 Water resistance
test: A basic water resistance test ensures the end
product is capable of withstanding moisture, especially
important for components used for desks and cabinetry. One of
my favorite trade show tests is submerging powderedcoated
component parts in water for several days, without any damage.
9 Gloss readings:
This test is performed to make sure the powder is performing
to manufacturing standards as well as meeting customers’
needs. This test should be conducted using a 60-degree gloss
meter. Powder-coated wood can be extremely moisture-resistant.
10 Colors: Just
because it’s new doesn’t necessarily mean it’s improved. Test
new colors for durability before committing to a customer.
This should be conducted using a SpectraLight Color Viewing
Booth and a production part, not just a sample part from the
powder supplier. Also, remember that cheap powder pricing is
not always the best option. How far the powder sprays per
pound, a determination made from the specific gravity of each
powder, is also important.
11ASTM tests: The American
National Standards Institute has many other tests that can be
performed to determine quality and performance requirements,
such as UV testing, shrinkage and heat resistance, etc.
Summary
It is important to point out that wood powder coating is a
complex process as compared to metal powder coating. There is
a wide spread misconception that powder coating on metal is
the same as wood. The similarities are there is a substrate
and powder, and the process involves electrostatic adherence.
Metal is a natural conductor of electricity, and wood is not.
Powder formulations and shelf life differ greatly from metal
to wood. For highest quality wood powder coating, excellent
results are obtained using premium quality raw materials, and
having the technical expertise and craftsmanship and a well
documented quality control process commitment. This commitment
to success requires millions of dollars and years of time and
testing to provide what can be the finest quality and durable
finish available in the wood manufacturing industry. When it
comes to ensuring quality, it’s really a matter of buyer
beware. Ensure that quality controls are in place so that you
receive a quality and long-lasting product.
Editors Note: Craig Martin is
President of BTD Wood Powder Coating, contract manufacturer
of powder coated wood components. For more information on
BTW Wood Powder Coating, please visit the company’s website
at
www.btdwoodpowdercoating.com or phone (218) 828-4144.
|
