Marcos Maniacs

Hi Maniacs,
The saga continues? As promised in the last installment, I have sanded
out the areas between the "legs? of the spider cracks.  Thus, instead
of repairing the many legs I can make one large repair for each set of
spider cracks and in some cases combine two or more spider cracks into
one repair.  
     If I were going to repair a small spider crack I would open up
the crack as was illustrated in yesterdays photos with a high-speed
grinder with a carbide bit.  When the original spider crack had been
opened up until the crack was gone I would then proceed to fill it
with a fiberglass and resin mixture.  If you use ?body filler? at this
stage there is a real good chance that the crack will reappear.  The
modern body fillers have made great advances but I still haven?t seen
any that are really effective in repairing spider cracks permanently,
although there may be some that do.  One brand commonly called ?kitty
hair? is fairly strong, but more trouble than it is worth to try to
repair spider cracks (in my opinion). For myself, I make a mixture of
chopped up fiberglass mat and resin to fill the cracks.  The mat needs
to be chopped into short pieces approximately ¼ inch long.  Most of
the ?chopped glass? that you see in the stores is too course for our
use on spider cracks.  Chop up a lot of fiberglass.  It is the
fiberglass, not the resin, which gives the repair the strength that we
are seeking. If the chopped up fiberglass is too long it will tend to
?bridge? the crack creating a void underneath.  So cut the mat up
fairly fine and it really can?t be ?too fine?.  Once you have the
chopped fiberglass ready, mix up some resin and paint the crack with
pure resin (I?m assuming that the crack is absolutely clean and free
from oil, wax, paint etc.).  After painting the crack with resin, take
a mixture of resin and glass and fill the crack to the surface.  Work
out any air bubbles and voids.  If you are using polyester resin you
will see some shrinkage so overfill the crack slightly. Anything that
sits ?proud? of the surface will be sanded away.
    Since I have opened up the spider cracks into ?repair areas? the
technique is slightly different. Please remember, that what makes this
technique possible is the additional layers of glass that I applied to
the backside.  Without that additional fiberglass on the backside, I
would have large gaping holes in the panel.  At any rate, the 1st
photo is a picture of the rear end with most of the areas ?sanded
out?.  Photo 2 is a close up of a ?sanded out? area.  Into the ?sanded
out area I cut some mat to exactly fit the void created by the
sanding.  If the mat is too large for the repair area, it will
?bridge? the transition area and leave a void unless you have made a
very large and gradual transition area. On this particular panel I am
using 2 layers of glass mat for each repair.  Once the mat is cut to
shape (two pieces per repair) I put the pieces of fiberglass mat on a
piece of wax paper  (the kind of wax paper that you wrap sandwiches
in). Then I take the resin, a disposable paintbrush and saturate one
piece of mat with the resin using the paintbrush to spread the resin
around on the fiberglass mat. The Mat will become translucent when it
is saturated.  Once it is saturated I place the second piece on top of
the first piece (which is saturated with resin).  I then pour more
resin on to the second piece of mat and spread it around until it is
also saturated.  You can use the paintbrush to saturate the top piece
of mat by stippling the mat with the paintbrush and getting the resin
from the first piece to ?wick? up to the second piece. However, you
run the risk of ?starving? the first piece of mat and not having
enough resin in the first piece. Once you are satisfied that you have
both pieces saturated, paint the repair area with resin and place the
mat into the repaired area. (yes, you can put the fiberglass mat on
the repair area dry and paint the resin onto it and then put the
second piece of fiberglass mat on dry and? My way is faster and better
but suit yourself.)  Now work out all the bubbles and make sure that
there are no voids in the repair area.  Photo 3 shows a repaired area
immediately after the mat was applied.  Photo 4 shows a number of
repaired areas in various stages of curing. Once the resin has cured
the repair will still not be flush.  Since I am going to ?build? up
this entire panel so I can sand it flat, this is not a problem for me.
 If I only wanted to repair the area in question, I would sand the
repaired area (or use peel ply or use laminating resin with out wax
and skip the sanding step) until the glaze was removed from the resin
and laminate another layer (or two) of fiberglass mat until the area
was slightly ?proud? after curing.  Then I would sand it flat. After
the repair is flat it is ready for the finishing steps (and this
doesn?t mean that it is ready to paint yet!)
More photos when they are warranted.
Mike Denman
1966 Marcos 1800
Chassis # 4079