I am close to finishing up as set of dining room chairs and have questions
regarding the upholstery techniques. On my test chair several years ago I
used a strip of 3/8" high density foam around the edge of the seat blank
which I tapered to give a scooped seat. I then covered that with another
3/8" layer to smooth the scoop curve and add padding. On top of that I
added 1" of what I believe was medium density foam and then cotton cloth and
the upholstery fabric.

I would like to increase the padding some. I have the FWW (#163) article
from a couple years ago where they used 1/2" HD foam on the bottom, a rim of
1/2" HD foam around the edge, and filled the center with 5/8" medium density
foam and a top layer of 1/4" low density foam. I like their edge HD with
a MD center fill, but I'm a little concerned about the LD breaking down with
time. I also checked Miller's book, but it used a simpler single density
foam approach. My inclination at this time is to go with something similar
to the FWW article and perhaps increase the thickness of the HD and MD
somewhat.

Are there any suggestions regarding the layer sequence, density and
thicknesses that the experts out there have found to give suitable support
and padding? Are there additional references that would be useful?

Thanks,
Bob Abbott



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Remove NOSPAM from address to reply

On Wed, 12 Jan 2005 11:16:55 -0800, "Bob"
wrote:

I like their edge HD with
a MD center fill, but I'm a little concerned about the LD breaking down with
time.

Foam doesn't break down in the centre, it goes at the front edge
first. I bet your HD edge will start to crumb long before the LD
centre does, even though the foam itself is more resistant.
Another tip is to fit a tightly fitted stockinette cover directly over
the foam (for loose cushions this can be a sewn envelope). By reducing
the looseness of movement in that very outer layer, it reduces the
crumbing.

Personally I just use a simple slab of either chip foam, or latex
foam. If I'm doing work for myself, I use traditional hair & hessian,
not foam. Anything in foam is sheer trade, and I don't have time for
fancy layups.

BTW - as a comparison with US and UK upholstery practice, what do you
guys have to do regarding fire-resistance certification of a piece you
make for sale ?

How expensive is foam ? It costs me £10 for a PU foam seat base
($18), twice this for latex foam, or four times for visco-elastic.

--
Smert' spamionam

Andy,

Foam doesn't break down in the centre, it goes at the front edge
first. I bet your HD edge will start to crumb long before the LD
centre does, even though the foam itself is more resistant.

In the method used in FWW the HD surrounds the MD center and a 1/4" layer of
LD covers the entire slip seat and wraps around to the bottom of the plywood
base. By "the front edge" do you mean the front of the seat where it gets
more stress or do you mean the outer edge of the foam layer? In this case
the LD foam is the outer edge of the seat.

Another tip is to fit a tightly fitted stockinette cover directly over
the foam (for loose cushions this can be a sewn envelope). By reducing
the looseness of movement in that very outer layer, it reduces the
crumbing.

There will be a tight layer of cotton muslin over the entire structure which
will be stapled at the back of the plywood base.

BTW - as a comparison with US and UK upholstery practice, what do you
guys have to do regarding fire-resistance certification of a piece you
make for sale ?

Since I'm making this for myself I don't have sale issues here. Perhaps
someone else reading can answer this.

How expensive is foam ? It costs me £10 for a PU foam seat base
($18), twice this for latex foam, or four times for visco-elastic.


I haven't priced it in a few years. I will be checking into this soon.

Thanks,
Bob

On Wed, 12 Jan 2005 20:12:18 -0800, "Bob"
wrote:

In the method used in FWW

I remember it, but not perfectly.

I'd do this by laying LD foam over the centre of the seat and having
the edge made from a ring of HD. Scarf the mating edge so that you
don't have a sudden transition from full-hard to full-soft.

I _wouldn't_ wrap with LD, and I _wouldn't_ take this scarf joint
right to the edge of the foam block. These would put LD right on the
edge, or even have a tapered-to-nothing edge right on the edge. Both
of these are putting thin LD foam on the most wear-prone area.

What I did last time (very thin seat on a plywood base) I tried this
multi-foam technique was to make the HD edge ring wide enough that
there was a narrow strip of solid HD foam at the front edge - the
tapered scarf to the LD began inboard of this.

Wrapping an MD block in 1/2" of LD foam overall is an old technique.
It's not one I'm impressed with though, having seen the front edge
collapse untidily in fairly short time. If you do this, then make sure
there's a curved edge to the inner block, not a sharp corner.


I might make one like that in the next week or two for this chair
http://codesmiths.com/shed/furniture...air_andrea.jpg
The back is trad upholstery that I rebuilt recently, but the seat is
just a loose squab. It needs a new foam cushion making up (rather than
the loose-wrapped old one that's in there now). I'll probably do it
in latex, as it's a keeper for myself.