- Jun 6, 2012Martin,
You have a very good point there. No matter what a plywood is called a
builder should look for plies that are equal or close to it. Some marine
grades now are not totally equal though. I think they start off all
equal but when sanded the outer plies get a bit thinner.
The other thing of course is the glue. If the core layer is softer than
the outer layers it can lead to glue starved plies even if the glue is
waterproof. This can happen with the stuff coming from China. How do you
know if it's coming from China? If it looks great and costs about 1/3
the price or less than marine you can be assured it's from China.
If in doubt I do the dishwasher test. Run a piece through the dishwasher
about 6-7 times on full cycle. What I have found with Sureply is that
the outer thin plies wrinkled a bit but never delaminated. One piece
wrinkled on one side and the other darker side stayed flat. So it may
work when glassed. If the layers are equal in an underlayemnt - no
problem with wrinkling. Luan underlayment falls apart. OK for pattern
makin in boat building.
Crezon MDO layers are actually equal thickness as an overlay is applied
after the sanding. It is heavier though as the cores are fir or a
related species. But no need to glass it unless you want abrasion
--- In Michalak@yahoogroups.com, Martin Houston <mtnridr13@...> wrote:
> I've never seen Sureply but I checked out Ultraply at Menards & didn't
like it. Seemed to have thick inner core & very thin veneers on either
side. I know many good boats have been built from it but I used premium
ACX.Â 3 equal thickness layers. Strong & takes screws & glue well.
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