Things that hold true regardless of the system used.
All fabric systems have to have a way to keep the sun’s UV rays from
getting to the fabric. There are two ways to do this, either
reflect the UV or to block the UV.
If you are reflecting it, several coats of “silver” are put on
under the color coats. Silver is clear butyrate dope or other clear
base that has fine aluminum power added to it. When it is sprayed
on it looks silver, hence the name. When using silver, it needs to
be heavy enough to keep all light from penetrating through. If
after it is sprayed on you can see any light coming through it, you
will need to add more coats of silver until the light is blocked.
If light gets through, UV is getting through and the fabric will
have a shortened life.
If you are blocking the UV then the primer and or top coat paint
must have a UV blocker as part of it. UV blocker is what is used in
sun screen to keep the UV off your skin. Light can get through but
the UV is blocked out. When blocking is used, all the light will
not be kept out so it can appear opaque.
With all the systems it is necessary to attach the new fabric to
the ribs to help keep the fabric from ballooning up. Normally just
follow what the manufacture did originally. The different ways
include rib stitching, fabric rivets, PK Screws, or clips. The
industry is moving away from the clips and sometimes the PK screws
and using approved fabric rivets.
Most Dacron fabric that is approved by the various suppliers comes
in three different weights. The light weight fabric is only used on
ultra lights and for finishing tape and weighs 1.7 oz per square
yard. The medium weight fabric weighs in at 2.7 oz per yard and the
heavy weight fabric weighs in at 3.7 oz per yard.
On most GA planes
I will use the 3.7 oz fabric on the bottom of the lower wings, tail,
and fuselage. On the rest of the aircraft I use 2.7 oz fabric.
Next - Dope Systems