One of the great advantages of this discussion group is its potential
to share information around about building processes, doubts, tips and
tricks that can be of great help to all of us.
In that sense I bring here an issue I feel could be helpful to many
When I began laminating the first float half I noticed the occurrence
of some white no-bond patches (WNBP) ranging in size from hardly
noticeable spots to some extensive areas clearly identifiable . If
it’s true that in most situations there was no risk regarding the
overall mechanical properties of the laminate in other cases some
grinding down and patching had to be done to insure laminate integrity
( close to the stringers for example).
This situation was not consistent throughout the subsequent laminates
and in most cases the occurrences were minimal. There was also no
particular technical procedure which could be identified as the main
cause for this phenomenon.
Before I got into the lamination of the exterior surfaces I had to get
to the bottom of this problem. Other builders ( Menno in particular)
referred the same situation and some discussion was developed around
this subject. There wasn’t however neither a adequate explanation nor
a solution for WNBP.
I suspected it either had to do with the presence of dust, chemical
bonding problem ( silane), boundary reaction between PVC and epoxy or
most likely , in my view, a combination of these factors. I noticed,
however, that WNBP never took place where putty had been applied. For
some reason it worked as a pore filler ( less dust buildup) and/or a
more efficient interface between foam and resin. If there was little I
could do about the chemical properties of foam and resin, I could
deal with the dust and putty factors.
I decided then to apply a thin coat of resin lightly thickened with
micro balloons , sand it down and do a meticulous vacuum ( 2-3
passes). Additionally I vacuum the floor and wet it out before
The result was excellent. In the first half hull I couldn’t find a
single flaw in the whole laminate. It was crystal clear and exhibited
excellent adhesion to the foam. On following laminations there were
some minor flaws of no importance, but no WNBP at all.
So, if you have experienced this sort of problem, you might consider
doing the same. It leads to some extra work but it clearly pays off.
Besides , applying a pre coat of resin with micro balloons will seal
the pvc pores with a layer which is lighter than plain resin. The
extra sanding needed will also work towards the final fairing process.
Although recommended , there’s no need to saturate the whole surface
with the resin/filler coat. I used a roller and tried to spread the
mixture as much as I could but couldn’t help leaving an irregular
distribution with some areas more saturated than others. Maybe you
could improve this method by using a squeegee or some other procedure.
You can check my blog www.matosf22.blogspot.com
information and photos.