Michiel wrote:

Matt and everyone else who responded to my questions:

Thanks again for sharing your experience and knowledge. Very cool!


With regards to urethane, I ran into this:

http://www.azom.com/details.asp?Arti...ison_of_Core_1

Judging from this page polyurethane foam might not be very suitable
for a deck, although I'm not sure if the writer had the higher
densities in mind. It seems to me that the expansion of the foam would
help to make a good bond?


I did a few things this weekend to find out what state things are in.

I went around the deck with a rubber mallet to try to figure out the
extent of delamination. I think it's very widespread. Only at the
edges, things sounded hard. But I guess that it this point that's
good, because it'll make it easy to take out the old core.

I also cut out a small patch, from the inside. It was frozen when I
cut it. It's almost dry now. It doesn't look or feel rotten at all,
but it looks as if frost may have caused some damage (some cracks in
the wood). the balsa is still firmly bonded to the inner skin. It
seems the delamination is just between the outer skin and the balsa. I
can take a photo of this if it would help.

I think I may be able to reuse the existing core. The procedure I'm
thinking of now is: Cut out the inner skin, let it dry thoroughly,
Remove core in areas where deck hardware will be mounted and fill with
resin as suggested by another poster, then smear a fat coat of resin
around (be it polyester or epoxy), maybe thickened with some
microballoons and prop the whole mess up and then when it all dries
glass over the cuts.

Michiel
PS: vacuum bagging sounds like a wonderful technique, but I just can't
afford the investment now.



You can prop up under the side deck with garbage bags of air and
other junk. It may be easier then sealing vacuum bagging. When I
tore up my side deck, I observed that where seepage had frozen, it
broke the bond with the end grain of the balsa, and allowed water to
progressively advance, freeze and thaw, cycle by cycle, year by
year. Once the bond is broken, by expanded frozen water, the open
end grain allows the balsa to get wet. If it freezes, it then tears
the bond to the next adjacent healthy core section, and the cycle
progresses. If the balsa is not rotton it can be dried and
rebonded. Otherwise, it progresses from light and strong to dark and
mushy. The mush must be removed and replaced, and must be groped
out inch by inch. I used a couglins folding camp saw with a couple
of extra teeth filed in the curve outside the end. Is it ever
wicked looking, now! If the cycle is stopped, any core will do, so
long as it stays dry. The cycle is started only by leaky stanction
bases, etc.

Seal up your side decks now! stop this cancer before it starts,
it's a lot less cure than otherwise.

Working under the side deck is only possible if there are no
cabinets, etc in the way. The amount of work counts for more than
technique or materials.

Terry K