Ply boil test question

After an hour in boiling water what is considered a failure? I boiled one piece, put one piece in cold water, and left one piece dry, for one hour. The dry piece was difficult to pry apart with pliers and a screwdriver, the wet piece was also pretty hard to pry apart, the boiled piece was not too difficult to pry apart. The boiled piece did not fall apart on its own in the water. Good, bad, or what? This is for cheap canoes, rowboats, and such.

 

The usual boil test is more then just boiling the wood. Unless you plan to park your boat over top of an active underwater volcano, it's not as useful a test as the military makes it out to be.

Testing materials for marine use should try to mimic the environment (accelerated of course) to see what the rate of deterioration will be.

Most plywood available in this country will have a stamp on it (probably more then one) which will tell you what kind of adhesive and lumber species are in the construction of the panel. The adhesives are rated WBP (Water & Boil Proof) Type I, Type II, etc. A sheet marked BS 1088 is good stuff, BS 6566 a little less as good, APA 1-95 (these three grades are all marine rated) also is good stuff, though not as good as BS 1088. What does your plywood say?

There are many threads on this site covering plywood construction, the lumber types and the adhesives used. Use the search thingie at the upper right of the BoatDesign.net screen. You may also want to check with the manufactures of plywood.

 

It was bought at Lowe's
It says:

Sampling USA,LLC
5.2 mm Hardwood Plywood
Exterior (12549)
fsc:sgs-coc-1294

It appears to be pretty nice, no knots on either side, no plugs, and with my battery operated spot light shined through it, no voids. I checked through several pieces at the store, all looked about the same. It says 5.2mm, although it measures 4.5mm
Already built one boat that I am pretty happy with, so I hope its ok.