Birch Ply

[cs]

Got a question about using birch plywood. Got a piece of scrap here that is about 12" wide and 5' long and 3/4" thick. This is about perfect for what I need and would save me having to buy a piece of solid lumber. It would be used above the water line on a day sailer. Coated with epoxy and painted. I can't tell if it is glued up with exterior glue, but I'm thinking that coating with epoxy would take care of that. This is stamped on the edge and I need a translation.

3/4 WPF TPD Wht Birch 9-PLY B-2

Figured out the 3/4 (3/4" thk) and the WHT Birch means white birch. Don't know what the WPF TPD means or the B-2. As far as the Plys it says 9-Ply but I can only count 7. Does it have a finish ply on each side that I can't see that well? BTW no voids that I can see.

Chad

[ishmael]

Chad,

Virtually all ply is made with waterproof glue these days. As to the code, beats me. The face veneers on this piece are very thin, so maybe thats why you can't see 'em.

Not an ideal piece of stock for marine apps., but for the way you are describing it would likely work fine. Seal it well and keep it that way.

[Donn]

Chad...figuring out the code is not easy. IHPA (International Hardwood Plywood Association) charges for the code, but, so far, I've found this:

B-2 means that the face veneer is "B" grade:
May be bookmatched (no sharp contrast at veneer joints)
Slight mineral streaks
Vine marks, small repaired knots, conspicuous burls
Two 1/8" x 6" blended repaired tapering hairline splits

and the back veneer is "2" grade:
up to 16 sound tight knots; repaired knot holes; sound tight burls and mineral streaks; up to six repaired splits or joints (1/8" x 12").

http://www.reimerhardwoods.com/grading.asp

Here's some more...WPF means "whole piece face"

http://www.awi-wa.com/_hidden/T_ABBREV.htm

[ 06-12-2002, 10:40 AM: Message edited by: donnwest ]

[NormMessinger]

Before I used a piece of hardwood plywood that is not to BS1088 standards I would confirm that it is indeed made with water proof glue. I didn't think furniture grade veneers were.

Hey Ish, how ya been?

--Norm

[John of Phoenix]

I can't help with the code Chad, but we can always count on Donn for good research.

If you can spare a piece of the wood, you might try the dishwasher test. Cut off a few square inches and run it through the diswasher a couple of times. If it holds together through that, it'll hold up on the boat.

[Donn]

I've exhausted my search ability, and I'm pretty sure TPD isn't one of these:

temporary partial disability
toilet paper dispenser
tons per day
treatment performance data( soil treatment analysis)
Troy, Tampa, Tuscon (etc) Police Department
Therapeutic Products Directorate (Canadian health agency)

= = = = =

Found this, though...a very nice list of plywoods, with sample photos and descriptions:

http://www.woodmosaic.com/encyclopedia/samples.html

[Figment]

I've got the 20-pound AWI (american woodworking institute) manual here in front of me, and the best I can do is to determine that whatever "TPD" stands for, it's to do with the exposure classification of the panel.

but anyway.... I agree with posts above. if your application for this piece isn't going to affect the structural integrity of the craft, go ahead and use it. (properly sealed, of course)

[reddog]

Chad;
Most likely your birch ply is for interior cabinet construction and not glued with a waterproof glue.An exterior grade phenol resorcinol glue will have a dark red or purple glue line.Interior ply is glued with a phenol formaldehyde glue and will delaminate in wet conditions.They count the face veneers as plys even though they are very thin.
You may be able to isolate it with epoxy and glass or dynel cloth but why take the chance.
Good luck;Earl

[ishmael]

Maybe it has changed, but when I was doing cabinet work, fifteen years ago, all the cabinet grade plywood sold in the US was glued with waterproof glue. 'Course, I never ran it through the diswasher, and merely believed what I was told. What do I know?

[reddog]

ishmael;
The birch ply up this way is usually intended for interior use.I haven't tested it by immersion but it doesn't last long outside.The US may have different standards for glues or the supplier may have confused water resistant with waterproof.
By the way it's good to see you back.
All the best;Earl

[wolfietuk]

I have to agree with reddog on the waterproof/waterresistant glue. The birch ply we use in cabinets is great for that. But it doesnt last long outside. If it isnt structural and you dont have to put a lot into finishing it try it and you only lose a little time. Remember with the 1/64 or less veneers you cannot sand out any dings that may occour.

Rick

[ishmael]

Red and Wolf...I'm glad to know that. As Bogart said regarding the waters of Casablanca,"I was misinformed."

[bud]

Not quite to the point, but I have been moving away from birch ply in my business and using MDO. It's a bit cheaper, more stable, water resistant & easier to work with.

[Figment]

MDO and MDF are pretty hot. we've been using them exposed in a few buildings and on some furniture in applications where we would otherwise have done maple ply.

our recent favorite technique is to stain/dye it a deep burgundy color and then do a satin poly finish. it comes out looking like leather.

but because it's so dense it's really too heavy for most marine applications.

[Rosebud]

We had a scrap of 3/4 inch furniture grade birch plywood and a customer who needed a bit of joinery in his stateroom. We left a test piece of the ply out in the weather for a week - 2 ro 3 rains/dry outs. It looked good - whereas some exterior ply we've bought will deteriorate in one rainstorm. The ply had no voids. 4 years later it is holding up perfectly.

We would use it in an interior or above the waterline place - if you have to.

Marine mahogany ply is better for the long run.

Good Luck-Jim and Kim

[ErikG]

I was going over some cheap alternatives before I started my boat, and had a piece of the same stuff lying around my shop. I subjected it to Sam Devlin's plywood torture test which consists of cutting a 4"x4" piece, boiling it for 20 minutes then sticking it in the freezer for the same amount of time, then putting it in the oven on warm for a few minutes until the exterior surface dries. You repeat this three or four times. If it doesn't look pretty much like what you started out with, don't put it on a boat.

The beach ply failed miserably. I couldn't believe how the stuff just came apart. I didn't even get to the third round and I could peel the layers apart with my bare hands. Save yourself trouble down the road and use solid wood or marine ply.

Just my opinion, of course.

[Chris Coose]

That board belongs in place, holding books in the air.
Even if you used a piece of teak it would cost about $60.00. By the time you fit and fasten the thing and prep it and paint it you are still going to have a piece of plywood that you'll look at and wonder if and when it will STB.
What's that worth?

[Eric Sea Frog]

All exterior grade ply I bought in France had dark glue lines, all interior ply had white glue lines.
Now marine grade is still a better, costly quality that has supposedly no voids.
A ply panel that has white glue I wouln't find fit for boat building, though an epoxy coating will of course delay the fan-hitting moment when water will contact the wood laminations and start gradually separating them.

Sail Safe !

[wolfietuk]

a note on mdo/mdf. These are completly defferent products. Mdf- medium density fiberboard- has some great attributes: low cost, dimensional stability, machinable, and smooth. and some bad; It is heavy, and IT SOAKS UP WATER LIKE A SPONGE. Both of which limit its usefulness in boat building to patterns and templates and the like. MDO - medium density overlay, also called sign board- is a decent grade exterior (yes it has dark glue) plywood. for its veneer it has a sheet of thin mdf (read paper) treated with some resins whitch make it more water RESISTANT. Both are great products when used for what they are designed for, and that is not boatbuilding. Remember, all plywood will eventuly delaminate. The different glues just determine how long it will last before it does.

Rick

[jason stumpf]

with regards to MDO, i believe the overlay is more akin to craft paper, with resin added for durability. and while MDF is indeed a thirsty board, there are waterproof varieties. one brand is Medex, from the brand Medite. i've used it in houses for countertops and such, and i know sign makers who use it exclusively. left a piece outside for a few months and it was unaffected by
the weather. that said, i'd never use it on a boat. too heavy, smells bad, strength properties not in line with usuall boat lumber.....
jason