FIBERGLASSING

 

SURFACE PREPARATION 
Fiberglass cloth and resin is used to cover models that have a solid
surface. Sheeted wings fiberglass well. Fiberglass can be used over foam
surfaces too. It will not work over open structure. The surface should be
completely smooth. All holes should be filled. I use light weight whipped
spackle from the hardware store. I use a 4" x 8" x 1/2" plywood board
with 40/60 grit sandpaper. I did not use any sand paper any finer! Use
rougher sandpaper to shape the surface, smoother sandpaper to prepare
the surface. Since the surface will be covered with cloth, 40/60 grit fine
enough. Finer sandpaper can create a non uniform shape by sanding out
the softer areas. I know using rough sandpaper goes against thy very
nature of model builders but try it. It will save you time and keep your
shape more uniform. If you do not like it, you can sand with a finer sand
paper when you get done.
 
GENERAL AND SUPPLIES 

CLOTH-Light weight 
RESIN-"ZAP Z-POXY" 
THINNER-Denatured alcohol 
MICRO BALLOONS 
BRUSH-Any disposable! 
DEEP PLASTIC CUP-Easier to mix 
RUBBER GLOVES-Any disposable! 

I use the light weight cloth even for my large scale airplanes. I use
"Z-POXY" by "ZAP". The epoxy has minimal odor which makes it more
comfortable to work with. Disposable brushes are a must. Thinner is to
expensive to wash out epoxy; especially when you can get a brush for less
than what a soda cost. Rubber gloves are a must too. Epoxy is
carcinogenic. Nothing good can come from contact with the stuff. Besides, it is just too darn sticky. 
 

 

APPLICATION 
Cut the fiberglass cloth and spread it over the aircraft part. Do not try to go
over too much or to go around corners. Break up each part into several flat
sheets. Overlapping cloth on round surfaces is ok. Just try not to do too
much at a time or it can get you into a big mess. 
Mix the epoxy 50/50 well! After the epoxy is thoroughly mixed, add and
mix in Denatured alcohol. It should end up 50% epoxy (after mixing) and
50% denatured alcohol. It should be the consistency of water. Bush it on to
the cloth working it into the wood. Start in the center and work out ward.
Try to keep the pressure light. It will help keep wrinkles from forming.
Work out all wrinkles that develop. The goal here is to get the cloth
completely saturated and formed to the wood. The goal is NOT to fill the
weave! Not yet. Be patient. Thinning the resin will keep you from making a
big gooey mess! It will make a clean job!

 

REMOVE THE EXCESS CLOTH 

After the resin has dried, go around the border with a piece of 220
sandpaper and remove the excess cloth. Lightly sand the weave. At this point
the surface should be smooth with the weave not yet filled.
 

FILLING THE WEAVE

The cloth is still rough because the weave has not been filled. Mix
another batch of 2 part epoxy thinned 50% with Denatured alcohol.
Now begin mixing in micro balloons. Add a little at a time and keep
mixing until the mixture is like a cream, a thick cream. Brush this mixture
onto the fiberglass to fill the weave. Try to brush a fairly heavy coat. If it
looks a bit thick and uneven, that's ok. Now let it dry.

 

 

SAND THE RESIN

Now it is time to sand the finish. Start with 40/60 grit on a sanding block
or board. That's right, start rough. The rough sand paper will keep the
shape and surface uniform. Sand as much of the resin off without going
through the cloth. When the surface is smooth and even, sand with a
good grade of 220 grit. I prefer to dry sand. The microballons will make
the resin soft and dry. I cut the sandpaper into little pads and I change
them often. I go through quite a bit of sand paper but it is worth it. Life is
too short not to sand with fresh paper! If the weave is not completely
filled, it may require more application of resin and microballoons.

 

PRIMING

When satisfied with the surface, prime with a good sand and fill auto
primer. 

FINISHING

Sand the surface with 220. Sand most of the primmer off. Repeat as
necessary to fill all low spots. If there are pin holes, deep scrapes, or
other imperfections they can be filled with a number of items. Auto
glazing putty, and the green plastic model putty both work well. The
plastic model putty is much harder than the glazing putty but it can fill a
deeper crevice. If the fiber glassing is done well, either will work fine
because not much will be needed. When you add putty or filler, work
the filler into the low spots or pinholes with your fingers. 
 

 

FINAL PREPARATION

Sand the putty off, and prime again until the surface is smooth. The last
coat of primmer should cover the whole wing when finished. Uniform
primmer color will help keep the surface color uniform. The wing in the
photograph required only 2 coats of primmer to get the surface smooth.
The final sand should be with 400 grit. Try not to touch the surface with
your hands. The oil on your hands can get into the primmer.
 
YOU ARE READY TO PAINT!

 

The Finished Product: