Artpop
Seaman Apprentice
- Joined
- Nov 18, 2008
- Messages
- 38
I just wanted to pass on something I found interesting about MDO. I have used quite a lot of new MDO in my Bell Boy restoration project. I have also reused some of the old wood. The original 1956 sole and bulkheads were MDO from the factory (Bellingham Ship Yard). All of the old wood I removed was in amazing condition. No rot. Today, I noticed I had made an error in measurement for my head compartment, and had to remove a small piece of the new MDO that I had epoxied onto a bulkhead. The piece was 1/2 inch thick by 1 inch wide by 4 inches long. It was face glued and screwed to a 3/4 inch thick by 2 inch wide by 18 inch long spruce cleat. To remove the piece, I first removed the screws. Then laid a chisel flat against the cleat at the glue joint and whacked it with a hammer. The chisel was then into the joint by about 1/2 inch. So I pried up on the MDO. This was an attempt to separate the plywood from the cleat. What happened instead was, the plywood delaminated and splintered. A short piece with about 2 plys was left on the cleat. The rest in my hand. Then I put the chisel under the MDO and flat onto the spruce, and hit it again. This time the remaining piece of plywood came off. Check out the pictures. Notice the separation of the plys from the first whack. And the separation of the paper skin on the second. Some of the epoxy stayed on the spruce and some on the MDO. What impressed me was the large amount of phenolic resin in the skin of the plywood. And how hard it was. Basically the top layer of paper is extremely well bonded to the first layer of fir. The paper does not have any paper-like characteristics. It reminded me of a very thin circuit board laminated to the plywood. I had to exert a huge amount of pressure to separate the joint. Exactly what I was hoping for when I made the joint. Now I have to redo the darned thing.
