Different kinds of springs and other info
Jan 30, 2010 1:14 PM
Location: L.A. area
Joined: Jan 18, 2008
Points: 1161
http://en.wikipedia.org/wiki/Mattress

From the page above:

"Spring mattress core

The core of the mattress supports the sleeper’s body. Modern spring mattress cores, often called "innersprings," are made up of steel coil springs, or "coils."

The gauge of the coils is another factor which determines firmness and support. Coils are measured in quarter increments. The lower the number, the thicker the spring. In general, higher-quality mattress coils have a 14-gauge (1.63 mm) diameter. Coils of 14 to 15.5-gauge (1.63 to 1.37 mm) give more easily under pressure, while a 12.5-gauge (1.94 mm) coil, the thickest typically available, feels quite firm.

Connections between the coils help the mattress retain its shape. Most coils are connected by interconnecting wires; encased coils are not connected, but the fabric encasement helps preserve the mattress shape.

Here are five types of mattress coils:

  • Bonnell coils are the oldest and most common. First adapted from buggy seat springs of the 19th century, they are still prevalent in less expensive mattresses. Bonnell coils are hourglass-shaped, and the ends of the wire are knotted or wrapped around the top and bottom circular portion of the coil and self-tied.
  • Marshall coils are each wrapped in a fabric encasement and usually are tempered. In the case of Beautyrest, high carbon magnesium is added, while the steel itself remains untempered. Some manufacturers pre-compress these coils, which makes the mattress firmer and allows for motion separation between the sides of the bed.
    Bonell springs
  • Encased Coils or encased springs, are a component part of a mattress in which each coil is separately wrapped in a textile material. Encased coils may also be generically referred to as Marshall coils or wrapped coils.
  • Offset coils are designed to hinge, thus conforming to body shape. They are very sturdy, stable innersprings that provide great support.
  • Continuous coils Or Mira-coils, work by a hinging effect, similar to that of offset coils. In a basic sense a continuous coil is simply that, one continuous coil in an up and down fashion forming one row (usually from head to toe) of what appear to be individual coils. The advantages of how firm a support the continuous coil provides it is somewhat tempered with the "noise" associated from a typical Mira-coil unit. The largest company using a Mira-coil design, is Serta Mattress Company, though their coil units are supplied by Leggett & Platt.

Bonell springs are hour-glass shaped, which means their resistance increases with load. They are therefore best suited for firm mattresses. [my emphasis]

Pocket springs provide support along the entire length of the body. This design works to maintain natural spinal alignment throughout the night.

Re: Different kinds of springs and other info
Reply #40 Feb 1, 2010 8:11 PM
Location: L.A. area
Joined: Jan 18, 2008
Points: 1161
This falls under the "and other info" part of the title of this thread.
This has been posted here before but as far as I know the last time it was posted was in early 2008, so here it is again.

The following page has pictures of what is inside various mattresses. These are mostly older mattresses, though there are a few pix of newer mattresses with just cheap foam on top of springs.

I wish they had put the date of the manufacture of each mattress in each photo, but it is what it is:

http://www.savvyrest.com/mattress-industry-today/mattress-morgue
Re: Different kinds of springs and other info
Reply #41 Feb 1, 2010 8:23 PM
Joined: Dec 17, 2009
Points: 850
i love that page.  the two funniest are probably the "Vera Wang Designer Mattress" (made by Serta) because it just illustrates that these mattresses really all look the same inside despite the price difference. 

And of course at the bottom the Select Comfort air mattress....LOL too funny. 
Re: Different kinds of springs and other info
Reply #42 Feb 1, 2010 11:55 PM
Joined: May 3, 2008
Points: 827
That was fun!  Did you see the one with straw and a girl in a skimpy outfit?  That looked ancient!!!  I wish I could see a darn Spring Air!  It looked like they were all Bonnell springs, except the Simmons of course, the all foam one and the silly air mattress pump.  They sure didn't use much foam, those must be old oldies huh?

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