[VAL] Plywood and other usless info.

[JSmith1805@xxxxxxx]

I Start wd using plywood in the late 1940s and epoxies in  the 1950s In that 
Time I have learned a little something meby not much but here  goes.
!I have been connected with the marine industries for many  years But with 
airstreams for a very short time about 10 years Some of you have  seen The 
Silver Albatross I just did what my years told me that I wanted to do  with it meby 
good meby bad No matter when I am finished with it I will probably  ether 
give it away or burn it.
Plywood
The difference between marine ply and exterior ply is simply  this
Marine plywood has more ply's 3/4 exterior has 5 laminates and  there may 
well be some voids in the laminates it is only sanded on one side 3/4  Marine ply 
will have 7-9 ply's sanded both sides.No doubt it is much stronger  than A-C 
but unless you weigh in at 978 lbs How much strength do you need? 
As far as the glue in the early darts plywood was made in both  exterior and 
interior plywood would never allow interior plywood in our shop  because of 
the danger of a mix up Interior Plywood as I member was a Couple $  in1/4 in a 
couple $ cheaper. To day nearly all plywood is made with water proof  glue. As 
an example a couple of days ago my son was looking for a light weight  3/8 in 
plywood and Questioned me about Home Depot's sand ply I had a scrap and  told 
him to take it and boil it for 2 hours the test for aircraft plywood. he  
brought back the 2 x 2 in sample and it was intact.
Over the years I have attended boat shows all over the east  coast and have 
been approached by many venders of epoxies I chiseled samples  from as many as 
I could each seemed tho they had the total answered to all my  problems We 
checked them all never found too much difference except in price  none really 
failed the test The prices at that time would range from from under  $300.00 to 
over $500,00 a drum At that time I was producing laminated Sail boat  tillers 
one year 4500 left my shop I used the same epoxy i have recommed to many  of 
you.
In the early days before penitrating Epoxy came out we use to  thin 
laminating epoxy with lacquor thinner to seal plywood before painting it  worked quite 
well would not use it on rot but it is better than nothing.
Sorry about the length of the post Just some of the things I  have learned 
over the years And yet there is so much to learn and so little  time
Jim Smith