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 #38 Feb 1, 2010 5:57 PM
Joined: Dec 17, 2009
Points: 850
Leo3 wrote:
Thanks for the info.  I thought you were too young to know, guess I was wrong.  But Spring Air was popular in the US here.  I thought they didn't start changing hands until 5 years ago.  They were changing hands before that???

I knew Simmons had the wrapped kind, at least when I went looking you can feel the difference on those mattresses.  I never thought those wuld hold up in the long run.  Do they?  Doesn't matter now though Simmons is gone, but maybe someone will revive them.

There are a lot of rumours about what will happen with Serta and Simmons these days.  I don't think they are going to vanish just yet.  With regards to their pocket coils, they actually used to hold up exceptionally well.  If a pocket coil is well made it is in theory maybe even more durable than other spring systems because there are no lacing wires to destroy, and the lacing wires are always the weak point with any normal spring system.  But again, in this day and age this is totally irrelevant because the foam will break down long before this becomes an issue. 

And yeah, I am probably a little too young to know, its a good thing I have family thats been in the industry for a long enough time to know these things and pass it on to me.  I also have some limited first hand experience, we had a really old Simmons in our guest room that was probably 20 years old and felt pretty good, this was some time ago so I would say the mattress would have been built in the early 80's, so even though there was poly foam in it, it was a minimal amount. I have also cut open a lot of older mattresses taken from customers homes before they head off to be recycled. Lots of old Sealy's and Simmon's, most of the coils looked to be in very good shape. 
Re: Different kinds of springs and other info
Reply #39 Feb 1, 2010 6:19 PM
Joined: Dec 17, 2009
Points: 850
Leo3 wrote:
Spring Air's website does show the "zoned" springs like you saw 9 years ago then.  That is what they are selling now.  That is not what I have from 15 years ago.  Another gimmick that probably doesn't work!

My Spring Air from 15 years ago was called four seasons I thought, but that is what they named everything.  You also know names mean nothing, you can't compare my Spring Air to your friends, because we bought them at different stores and they change the names to protect the guilty, LOL!  See if his has silk fabric on one side, and wool on the other, mine does.  That is my advice to anyone who has an old filippable mattress, KEEP IT.

Yeah zoned springs IMO are a huge gimmick.  I will tell you what lead me to believe so.  My research on the worlds most expensive hand made mattresses made me realize that absolutely NONE of them zone their inner springs.  They might reinforce the edges, but they will never mess with actual sleeping surface.  My knowledge of suspension technology from being a hobbyist weekend auto-crosser gave me some rudimentary experience and understanding of how progressive springs work.  At the heart of it, all inner springs used in mattresses are progressive coils, meaning the diameter of the working wire is not the same through out the height of the coil itself.  A non zoned coil in one way shape or form ALREADY self adjusts the tension to match the weight of the sleeper in that particular area of the spring system.  If you bias the support in the middle of the spring system by either using a thicker steel or moving the coils closer together you are massively overcompensating, and it really just prevents the coils from doing the job they are designed to do. 

There is also the issue about the height of people being different, as well as the shape of a man vs a woman of the same height and weight.  The only way you can really bias support without compromising the ability of the bed to conform to the shape of someones body is to use different types of lateral support built into the base or the mattress ie; a slat system with adjustable tension in the mattress or the base.  It is however very rare to see this, because its expensive to do, and it somewhat complicates the process for some people who don't want to fuss around with these sorts of things.
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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