I built my MiniCups from cheapo plywood bathroom underlayment and now I
regret it. Should have used marine ply. The underlayment has serious
voids and places where there seems to be no glue. It isnt exactly
waterproof either and water soaks right through. I am now glass and
epoxy reinforcing them. The dinghy I built with marine ply seems very
strong with no voids. Of course, it is also painted with epoxy.
I would not willingly buy anything from China as their politics suck, I
object to slave labor and support the self determination of Taiwan.
Sorry about the political rant.

Brian D wrote:
When you say "China", I think "yeah, right". There is absolutely
nothing
guaranteed about Chinese quality. They can and will cheat whenever
they
can. They are still a communist country and are very difficult to
deal with
legally. I'm not just spouting off ...I work for a blue-chip high
tech firm
and we've had to chase down exactly these issues ...provision of
products
not meeting specifications or quality requirements, using substandard

materials rather than what we asked for, not protecting intellectual
property (confidential disclosures, nondisclosure agreements,
patents, etc
are not respected), and using Kopy Kat materials and products from
Chinese
companies that are illegally copying and violating the patents owned
by
western nations. Chasing things down legally is an expensive
dead-end.
Like I said, it's a big communist country that has little intention
to be
influenced by your concerns, even if they are ethically correct and
the
country WOULD benefit by cooperating with rather than ignoring your
concerns. Taiwan is little better.

That said, I would not trust the adhesives in plywood from China to
always
be correct. I would boil test a sample from every piece of plywood
that I
got and personally inspect the wood itself too. You might find
variation in
wood species in addition to variation in what adhesive they used. To
a
slightly lesser extent, these same issues apply to wood obtained from
3rd
world countries like the Philippines and Malaysia too. Wood from
Europe,
Israel, Canada, or the United States will in general NOT have these
issues,
but keep in mind that much of the available wood (especially Meranti,
Lauan,
and Honduras or Philippine Mahogany) is imported from the countries
that
have more of a quality issue than others. Also, check your ply for
squareness ...many of these other countries just don't have high
enough
quality control and non-rectangular plywood is common. Even the more

reliable countries are getting more slack on producing nice
rectangular
wood.

All wood should be encapsulated with epoxy to waterproof it, and any
species
that may be subject to splitting or checking would benefit from at
least a
light layer of fiberglass, even if only 1-1/2 ounces.

Brian D




"Danielle Anderson" wrote in message
.. .
Waterproffing is not the problem here. Pretty much ALL plywood is
made
with
waterproof glue. Marine plywood is about the highest grade of
plywood due
to it's ridgid spec requirement. Most plywood contains numerous
cracks,
voids, and large knots in the interior laminations. Often they
will be
repaired on the outside layers only. Marine plywood has very few
cracks,
NO
voids, and knots must be under 1/2 inch. Pay the extra money and
only do
the job once. Cut this cost corner at extreme risk of failure.

Jon


"Pop" wrote in message
...
Has anyone used the 1/2 in. plywood from China, Home Depot has
this but
it
is interior grade, colud it be used for boat building if it was
completely
sheathed in a waterproof material.