Doug,
At last a real conversation about wood and woodworking in here! Sorry but
the trolls in the newsgroup are really starting to bug me. I'm almost
embarassed to open this group up somedays.
I bow to most of your arguements on strengths and stabilities. The whole
thing is really relative to what you're comparing. Oak versus poplar versus
plywoods versus pine? All sorts of differing variables in the equation as to
the strengths and weaknesses of each. One of the weaknesses you get in solid
woods is the fact you pointed out that all the wood fibers run parallel to
each other. This makes it susceptible to shearing forces. Most pieces of
hardwood don't break across the fibers, they split at some point along the
fibers. All depends on how you use the wood.

But as to our poor posters original question (from which I've digressed) - I
wouldn't waste time finishing or worrying about wood movement. Just make
sure you have enough strength in whatever you use to withstand whatever
weight you'll have bouncing on your bed. For what it's worth, I've just used
old A/C plywood scrap for bed slats on my own bed frame.

And Doug, appreciate the intelligent wood discourse. And you're right - I do
need a new lumber supplier - mine just burned down last week!

Gary


"Doug Miller" wrote in message
.com...
In article , "Gary"
wrote:
Doug,
Disagree with your comment on plywood over solid wood. In wood of same
dimensions, plywood is much stronger than typical wood (especially
something
like poplar). You don't have the wood defects, splits, checks, etc than
can
weaken solid wood.

In my experience, such defects are far more common in plywood, than in
solid
hardwood. Maybe you need to find a different lumber supplier. :-)

Since plywood is laminated veneers of solid wood with the laminations
running at 90 degree angles to each others, it's resistance to breakage
for
something like a bed slat is much greater than a typical piece of poplar.

For a weak wood such as poplar, possibly, although I doubt it very much.
And you originally said "hardwood" without specifying species. At least
with respect to stronger hardwoods such as maple, ash, or oak, I'm sorry,
but
that's just not right. In a bed slat made of solid wood, *all* of the wood
fibers run the entire length of the slat, whereas in a plywood slat, only
about half of the fibers run the length of the slat, and the other half
run
across the slat. The latter contribute almost nothing to the bending
resistance, or load-bearing capacity, of the piece. The solid wood has
more
fibers contributing to its load capacity, and hence will bear greater
loads.

Plywood's laminations at 90 degrees to each other give plywood greater
dimensional stability than solid wood, and ensure that its physical
properties
across length and width are similar, much more so than in solid wood --
but
they do NOT add strength. Rather, they reduce it, in exchange for greater
stability and uniformity.


Gary



"Doug Miller" wrote in message
y.com...
In article , "Gary"
wrote:
Why finish them? Wood movement isn't necessarily a bad thing. You only
need
to control it where it wood is joined and movement of the wood can
cause
problems with some sort of joinery or attachement. Attach the bed
slats
with a screw through the middle of the slat to your ledger strip and
any
movement will be an expansion of the wood away from the screw.
Another thought - use plywood slats instead of hardwood. No wood
movement
and much stronger across it's length than hardwood.

Ummm... actually, solid wood is stronger.

"Bob N" wrote in message
. com...
Thanks for the helpful advice on scraping vs. sanding my son's ash
bed.
I
sanded to 220
and the first coat of finish (Tried & True Varnish Oil) is already
silky.

I don't want to put oil finish on the poplar slats since they
contact
the
mattress. Would
it be better to shellac them to reduce movement due to humidity
changes
or
leave them
unfinished?

Thanks.
--
Bob





--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)



--
Regards,
Doug Miller (alphageek-at-milmac-dot-com)