Notes on Discussion with Lee Boser at Spartech Warsaw plant 1/24/07
(From Bill Blatner)

Royalite is composed of an ABS foam core sandwiched between two yellow ABS
layers sandwiched between R84, Royalex’s name for the UV resistant skin.

The R84, which is only about .003 inches thick, is also highly chemically
resistant. So, unlike the vinyl layers on the outside of Royalex, Lee says
the R84 needs to be scuffed up and scrubbed with some MEK or acetone.  It
should then bond readily to a two-part epoxy adhesive.   According to Lee,
ABS pipe adhesive will work also, though it may weaken the ABS in the hull
slightly because the adhesive contains several powerful solvents needed to
melt pipes together.  My own experience suggests that the ABS cement should
be fine if a thin coat is used and kept to the area of the part being
attached.  As I think I mentioned, after replacing one of my leg strap
attachments with ABS cement, I’ve broken two leg strap buckles rolling -
so the weak link in the system is not the attachment to the hull.  For
items that don’t take a lot of stress, but which take a fair amount of
surface area in high stress locations (on the chines), I would use a simple
contact cement.

I asked Lee about the issue of devulcanization.  He said you don’t need to
worry about that (actually, he said that was bullshit).  Apparently, and
this is consistent with what I’ve read about it, vulcanization is a pretty
irreversible process, so that’s not a concern.

I described the common situation of bottom wear, as opposed to deep cuts,
gouges or cracks.  Lee recommended coating those areas with urethane, which
he said could be gotten in different colors.  I was unclear on what he mean
by this - not I presume the polyurethane you use on wood.  He suggested that
the urethane would bond to the yellow ABS layer under the R84 skin.  He said
this would provide UV protection.  I asked about creating the ABS slurry with
cut up pipe and acetone.  He said that would work and that it shouldn’t weaken
the hull because it doesn’t have the powerful solvents in pipe adhesive.

Lee also advocated Kevlar skid plates or patches to protect areas of high wear,
attached with ABS cement or the two-part epoxy.  I’m not so sure about this.
I think you’d be bonding a material with very different rigidity and strength
properties that could result in stress concentrations around the patch.  Lee
also isn’t thinking about the desire to keep weight down - every time we add
a layer of something or more outfitting it adds weight.