Tighten ARF Covering
User Manual: Manual MonoKote Dark Red 6' | HorizonHobby
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Some models are shipped
with tape holding some of
the parts together. Before
proceeding, remove the
tape and use small paper
towel squares dampened
with naptha (lighter fl uid)
to wash off any glue left
behind. Later, after you have
tightened all the covering,
CA debonder may be used
to clean off any pigmented
adhesive that gets deposited
on the model.
A model airplane covering iron with a protective cloth
cover will be required. The Coverite™ 21st Century®
Sealing Iron (COVR2700) is recommended because
it has a contoured shoe, a calibrated temperature
dial and a long cord. A covering cloth protects the
covering and balsa underneath, but more importantly,
distributes heat from the iron more evenly. The cover
cloth for the Coverite iron is the 21st Century Cover
Sock (COVR2702).
After attaching the covering sock to your iron, the next
thing to do is set the iron to the correct temperature
for the covering that is on your model. If your model is
covered with Top Flite® MonoKote® and you are using
the 21st Century covering iron, set the temperature dial
to 325°F [160°C]. This should provide an actual surface
temperature on the bottom of the sock-covered iron of
approximately 280°F [140°C].
If you do not have a 21st Century covering iron or if
you are not certain what covering was used, you can
determine the ideal iron temperature yourself. Most
coverings work best using as much heat as possible, but
not so hot as to cause seams to pull away or the covering
to form “bubbles” over where it is attached to wood. To
fi nd the optimum temperature, set the dial on your iron
to a medium/low heat. While pressing down on the iron,
glide it over covering on part of the model that is over
wood, such as leading edge sheeting or the bottom of
the fuselage. Observe the covering to see if any bubbles
appear. If bubbles do appear, the covering is too hot. Try
using a lower temperature until you can get the covering
to shrink and stick without bubbles forming.
If no bubbles appear, try more heat and repeat the test
until you can “zero in” on a temperature that will get the
covering to stick and shrink the most without causing
the seams to pull away or bubbles to form.
Once the ideal iron temperature has been determined
you are ready to begin. There are three objectives:
1) Remove wrinkles.
2) Tighten areas of loose covering (even if there are
no wrinkles visible).
3) Over framework and sheeting, securely bond the
covering to the wood.* To do all three correctly,
and to provide lasting results, you should go over
the entire model–including areas where loose
covering or wrinkles may not currently be present.
For most medium-sized models, this should take
about an hour.
*Even though there are no wrinkles and all the covering appears to be
tight, do not skip Step 3. Wherever the covering is over wood it must
be stuck down. Otherwise, over time or in the heat of the sun, bubbles
or other areas of covering that aren’t bonded to the wood may turn
into wrinkles.
Due to the nature of mass production, your ARF model’s factory-applied covering will probably require some attention to make it look the best that it can. Its appearance
can also be affected by variations in temperature and humidity between the time covering was applied and the time you remove your new model from the box. Please note
that removing wrinkles by hastily going over them with a heat gun or a covering iron will not provide the best, longest-lasting result. You should take your time to diligently
go over the entire model with a covering iron as described below.
HOW TO TIGHTEN COVERING ON ARF MODELS
HOW TO TIGHTEN COVERING ON ARF MODELS
To begin, using little pressure, place the iron on the part
and glide it from side to side over a 3-4" [80 – 100mm]
area. Once you can see that the covering has tightened
up continue moving the iron back and forth but apply
pressure to stick the adhesive on the bottom of the
covering to the wood—this is why a covering sock is
required. Otherwise, the iron could scratch the covering
and dent the wood.
Once you can detect the wood grain through the covering
you know it is stuck down. Move the iron over to the
next area and continue this process until all the covering
has been securely bonded wherever it is over wood. If
bubbles appear in the covering, move the iron faster or
use less heat. When you get to parts of the covering that
are over open structure (such as between wing ribs on a
wing that is not sheeted) do not apply any pressure.
In some cases, where you just can’t get air bubbles to
go away, use a sharp, new #11 blade to poke small
vent holes in the covering over the bubble and go back
over the area again. Sometimes, bubbles are caused by
resins in the wood or adhesive that may have been left
behind or wicked up through from the bottom.
Where sheeting is thin or soft over unsupported structure
(such as between wing ribs or between stringers and
bulkheads in the fuselage), it may bend inward causing
the covering to stretch even though you are trying to
shrink it. Where possible, reach down inside the model
and support the sheeting with your fi ngers while going
over the outside with the iron. Where you can’t reach
in, lightly glide the iron over the area using little or no
pressure—more heat may also help even if it causes
the covering to bubble slightly. If you still cannot get
the wrinkles to disappear, use a second iron without
a protective sock to apply even more heat. Once the
wrinkles over soft sheeting are gone, you can lightly go
back over the area again with your sock-covered iron.
When tightening covering on smaller parts that have
open structure (such as elevators, rudders, or parts
of small models), the covering must fi rst be securely
bonded to the structure all the way around. And, if there
is not enough overlap between the top and bottom pieces
of covering and around the edges, and if the edges
are not stuck down, the covering may loosen and pull
away from the structure. Use your iron with a covering
sock to bond the covering to the framework all the way
around. Press down and make sure the covering is
thoroughly attached.
Additionally, air inside smaller parts needs to be
ventilated. Otherwise, sealed in air will expand, causing
the covering to stretch instead of shrink. Use a pin to
poke small holes in the bottom of the covering between
each rib.
After the covering has been bonded to the framework
and vent holes have been punched, the covering may
now be tightened. If you can’t get all the wrinkles out or
if you can’t get the covering tight enough, use a covering
iron without a protective sock to apply more heat, but
don’t heat the edges at the same time or the covering
may pull away.
Copyright © 2008 ZZZZ5000
