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Finishing Bendable Ply/Luan

PostPosted: Fri Mar 24, 2006 4:46 pm
by Loader
I just picked up my 1/8 bendy plywood, and had a question about finishing it. (couldn't find it on the search)

I want to use some spar urethene, however, not sure if I should apply it before installing or after. Will the urethene crack when bending the ply?

It sure would be a lot easier to apply with the ply on the sawhorses.

Thanks all.

PostPosted: Fri Mar 24, 2006 4:55 pm
by Chris C
YES!!!!!!!!! No question! Don't apply the finish until you're finished! (is that a pun?) :lol:

PostPosted: Fri Mar 24, 2006 8:22 pm
by madjack
...we did the complete finish to all wood pieces before they were assembled including the bendy ply which had a pickled stain and 3(r4) coats of Polycyllic onit...it didn't crack on us which was a worry....YMMV
madjack 8)

PostPosted: Fri Mar 24, 2006 10:35 pm
by Loader
Thanks guys. As much as I really don't want to apply the varnish/urethene after it is installed, I think that is what I'll do. Well, my wife will actually apply it, she handles the brush better than I do.

PostPosted: Sat Mar 25, 2006 3:02 pm
by Ira
It's not just the applying--it's the sanding BETWEEN applying.

I spar varnished my roof (1/4" bendy birch) after it was on, and it wasn't a MAJOR pain in the a** getting up there up top to apply, sand, and apply thrice again. (I used mega-expensive stuff--Pratt & Lambert's Vitralite.)

But if I knew I could do it before-hand on saw-horses, I probably would have gone that route--although I was in a rush to get the roof on because the rains were coming here.

PostPosted: Sat Mar 25, 2006 8:29 pm
by cracker39
[quote="Ira"]It's not just the applying--it's the sanding BETWEEN applying.

I spar varnished my roof (1/4" bendy birch) after it was on, and it wasn't a MAJOR pain in the a** getting up there up top to apply, sand, and apply thrice again. (I used mega-expensive stuff--Pratt & Lambert's Vitralite.)

But if I knew I could do it before-hand on saw-horses, I probably would have gone that route--although I was in a rush to get the roof on because the rains were coming here.[/quote

Ira, You think your's was a bear to work on the top? Just think of what I'll go through. Mine will be just about 7 1/2' high at the peak. I'm doing my sealing with thinned poly varnish on the roof skins on saw horses before installing them (starting the sealing tomorrow). But, I'll have to fill the joints, sand, prime and paint the top using a ladder. That'll be fun (NOT). Maybe I'll take off the wheels and tires, put it on low blocks for the finishing, then after it's painted, jack it up to put the wheels and tires back on. But, that will only reduce the height by 6 or 7 inches.

My wife mentioned today that she would like to see it with the door and windows put in. But, those will be installed much later, after it's painted and the interior paneling is installed. She also asked how long until it's finished and where are we going on our maiden voyage. I haven't even thought that far ahead. No idea how long to complete it (i'd say 3-4 weeks...maybe), and the first trip will probably be somewhere within a hundred miles to shake out the bugs.

Re: Finishing Bendable Ply/Luan

PostPosted: Sat Mar 25, 2006 10:33 pm
by TomS
Loader wrote:I just picked up my 1/8 bendy plywood, and had a question about finishing it. (couldn't find it on the search)

I want to use some spar urethene, however, not sure if I should apply it before installing or after. Will the urethene crack when bending the ply?

It sure would be a lot easier to apply with the ply on the sawhorses.

Thanks all.


I used 1/8 " bending birch plywood for the inside roof skins on my tear and on the inside of the galley hatch. I applied 3 coats of Minwax spar urethane, sanding between coats, before installing in my tear. I had no problems whatsoever with the urethane crazing or cracking during installation. And, it sure is easier to sand and apply the urethane with it laying flat on a work table.

Image

PostPosted: Sat Mar 25, 2006 10:35 pm
by Chris C
WOW!!! I stand corrected! Big surprise to me. :shock: Sorry if I gave you the wrong info. :oops: (Dang, that's THREE times I've been wrong this year!!!) :lol:

PostPosted: Sat Mar 25, 2006 11:16 pm
by madjack
Chris C wrote:WOW!!! I stand corrected! Big surprise to me. :shock: Sorry if I gave you the wrong info. :oops: (Dang, that's THREE times I've been wrong this year!!!) :lol:


...are you sure that wasn't 3 times TODAY :lol: :lol: :lol: ;) ................................................ 8)

PostPosted: Sun Mar 26, 2006 1:15 am
by asianflava
I put mine together before I finished the inside. At first, I used a foam brush but found that to be a pain when doing the ceiling. Getting polyurethane dripped on you can be a PITA. Then I fired up the cup gun and sprayed it. It took a little while to get the gun set up but it went on pretty easily. There are a couple places where I didn't sand as well as I should have but I'll sand it and touch it up with the spray can stuff.

PostPosted: Sun Mar 26, 2006 7:36 am
by cracker39
Although the poly varnish in the spray can is a lot more expensive per ounce, I use the spray cans for small projects to save all the hassle of setting up the paint gun and then having to clean it. I don't think I've ever brushed on varnish. I prefer straying...it's faster and I think it gives a smoother finish (smoother than my brushing anyway).

PostPosted: Sun Mar 26, 2006 8:03 am
by Loader
Thanks for all the advice, I installed the inner skin yesterday, before finishing it. So, a learning experience for me. I'll do the hatch skin on the sawhorses.

PostPosted: Sun Mar 26, 2006 10:40 am
by Miriam C.
I to brush poly on a desk and my son handed me a sweat sock. worked great. No brush strokes and smooth finish.

:lol:
Those look so good
Miriam

PostPosted: Tue Apr 04, 2006 3:38 pm
by Todah Tear
My tear will be 5ft wide, but the board that I have is only 4ft wide. How have people been splicing two sheets together smoothly?

PostPosted: Tue Apr 04, 2006 3:58 pm
by cracker39
My TTT is 5' wide and the cabin from Point to Point is 12'. So, I had to use 3 sheets for each side and the top. There are other methods of joining sheets, but the method described here worked out fine for me. I made sure that a vertical 33/4" thick by 3" wide framing piece was in the side for each joint to be attached to, and a 1 1/2" x 1 1/2" spar in the top for joints.

On each skin piece, I beveled the edges that join at 45" for about 2/3 of the thickness. This allowed a "V" groove just over 1/4" wide at the top to fill with bondo. I attached the skin pieces with TBII glue and screws about 8"-10" apart and used my brad nailer to put a couple of brads inbetween the screws to make sure the edges were fastened securely to the framing. All of the joints are practically undetectable after putting on some primer.