Aside from a few stationary tools like the
spray booth, air compressor and maybe a wide belt sander, most
of the finisher’s arsenal of tools are hand held. Hand sanders,
spray guns, air hoses, regulators and filters are just some of
the tools used in the application process. Then there are the
material handling tools like dollies, drying racks, saw horses
and carts. Half of the processes and most of the time in the
finish room is spent moving material. It only makes sense to
have the racks and carts to do it efficiently. It also makes
sense to place the carts so you save footsteps.
You Have the Tools Necessary to do the Job Efficiently
Don’t take anything for granted. I was at a
very large company and as I walked by the stain booth I noticed
the finisher was holding his gun back about 3 feet from the
piece he was spraying. The gun was producing a huge rush of air
and a large cloud of overspray. I couldn’t help myself, so I
asked him what he was doing. He replied that he has spraying dye
stain. I asked him what he had his air pressure set at. He said
about 75 psi - about 3 times the required air volume. Now I was
intrigued, so I asked him why so high. He said that he didn’t
have a blow gun to dust off the piece before he sprayed it so he
just turns the pressure to the gun up real high so he can use it
to blow off the piece. Then, he says, if he holds the gun way
back here he can control it enough to be able to spray on the
Sometimes the simple addition of another
regulator, spray gun, sander or even a couple of extra hoses can
afford a large increase in productivity. In this situation a $12
blow gun was costing this company hundreds of dollars a month in
stain, not to mention the cost of the compressed air and booth
is invested in your tools will be paid back many times over by
increased quality and productivity.
Tools Set-Up Properly
Once again, don’t take anything for
granted. Just because a tool is brand new, or appears to be
working alright don’t assume that it is operating at its best.
This axiom is particularly true with spray equipment. Often guns
have improperly sized needles
and fluid tips for the material that they are spraying.
The finisher will quite often over-reduce the material or modify
their spraying technique to compensate for this situation -
People Principal #2. This result is higher VOC’s, less film
build and increased labor. Your equipment supplier should have
the information and parts necessary to remedy this problem.
Compressed air systems are also prone to
performance problems. Parts get replaced; piping gets added to
or moved. This can often lead to moisture in the lines or
restricted air flow. Either of these problems will impact the
performance of your spray or sanding equipment. Sometimes the
culprit can be something as simple as an air hose that is too
small in diameter or the installation of a reducer in the main
The compressed air system is at the head of
the finishing tool chain, so any problems it introduces will
effect everything that comes after it in the chain.
quality of your finish and the consistency of your color begin
with sanding. It is one of the most important steps in your
finishing process. This being said I find it ludicrous that this
is the job that most shops give the “new guy”.
to approach sanding from the perspective of the finish and not
your finger. Of course you sand to level joints and smooth the
surface; however you are also providing a uniform texture that
will help take stains evenly and provide a tooth for the finish
to grab on to. The correct grit selections and type of paper are
crucial. Many of the high solids finishes require less white
wood sanding than their older counterparts. Over-sanding is not
only counterproductive, but will ultimately encourage adhesion
to investigate different sanding schedules and sandpaper types.
Work with your abrasives supplier. Run tests and compare
results. You may find some ways to cut time and improve quality.
There is another way of reducing sanding
time that is not directly related to your abrasives. Some people
spray out finishes, especially primers using a poor quality gun
and without the proper reduction, usually resulting in orange
peel. Their feeling is that you just have to sand it anyway so
what is the big deal? Well, for
every hour you spend waving a spray gun over the wood you will
spend 3-5 hours sanding what you just sprayed. It only makes
sense that the smoother a sealer or primer goes on the less time
you will spend sanding it out.
about swirl marks. If you have them, then there is a problem
with your sander, your system or the person using it. An
adequately powered, properly maintained sander, using the
correct progression of grits will not swirl. Notice the
keywords: adequately powered, properly maintained and correct
progression of grits.
3 basic types of spray guns used in professional finishing
operations; Conventional, HVLP and Air Assisted Airless. Their
names refer to how the finishing material is atomized. The terms
siphon feed, gravity feed and pressure feed refer to how the
material is presented to the spray gun.
spray gun system that you use can affect your bottom line in
a couple of different ways.
Will affect the amount of
reducer that you need to add. Systems that feed the material
to the gun under pressure tend to require less reducer than
a siphon system which is trying to suck the material up
through a tube.
Will determine not only how
often you have to stop and refill your material supply, but
it also has an effect on operator fatigue. Not only do you
have to stop more often to refill that quart cup, but that
quart cup of primer adds about 2 ½ pounds to the weight to
the gun. At the end of the day it feels like 2 ½ tons.
Will have an effect on the
amount of time and materials required for clean-up.
Obviously it is going to require less solvent to clean up
that quart cup than it is to blow through 20 feet of
The method of atomization
affects the amount of material wasted in overspray. This is
called the transfer efficiency.
efficiency is a term that refers to how much of the material
that comes out of your spray gun sticks to the wood versus how
much bounces off and turns into overspray. The velocity that the
material exits the gun has a lot to do with it’s Transfer
Conventional – 40%
Thinking of it in a different way; for
every $100 worth of finish
$60 up the stack
HVLP puts $35 up the
Air Assisted Airless
puts $20 up the stack
The switch from a conventional gun to a
HVLP should be a no-brainer. The material savings alone will pay
for the new gun. When deciding on your feed system, or if you
are thinking about moving up to an air assisted airless you
should consider the volume of finish that you shoot in a day, as
well as the number of material change-overs that you perform.
While Air Assisted Airless systems are pricey they do offer a
significant savings in material because of the high transfer
efficiency and they consume about 1/5th the compressed air of a
pressure pot. Since they generate less overspray than the other
systems usually there is a reduction in sanding times on items
like drawer boxes and cabinet interiors, plus your finishers,
your booth and it’s filters stay cleaner longer.
– nothing lasts forever
It can be
hard to justify maintenance time since on the surface it appears
to be non-productive time. The exact opposite is true. When and
how well you maintain your equipment can have a huge impact on
your productivity and the quality of your finish. It can also
directly impact the morale of the people using the equipment.
The “if they don’t care then I don’t care” attitude can have
devastating effects on your products, so make maintenance
routine. Invest in rebuild kits for your spray guns and
replacement pads for your sanders. Murphy’s Law says that you
are going to need them right in the middle of a rush job. That
is not the time to try and hunt them down and go get them.