Mattress Forum

• Coil count
• Gauge of wire
• Type of coil
• Working turns (actually, I heard this somewhere, but did not run across the term even once tonight.)
  

• 231 11x21
  
• 252 12x21
  
• 312 13x24
  
• 325 13x25
  
• 336 14x24
  
• 364 14x26
  
• 405 15x27
  
• 510 17x30
  

• 308 14x22
  
• 330 15x22
  
• 368 16x23
  

• 432 18x24
  
• 660 22x30

• COIL COUNT - The first game that you have to watch out for involves the coil count. In the industry, coil counts are quoted by the full size - regardless of what size you're actually buying.

• ...[a] not so ethical salesman might take advantage of his customer by quoting the actual coil count of a lesser quality bed. For example look at the chart again under Bonnell but this time follow the 252 across to the King column 16x23 which equals 368. So the uninformed customer might think they were getting a bargain when in reality they're getting taken.

• The 312 unit was the standard coil unit specified by most hotel chains. It did not stand up to the heavy demands placed on it so now the 336 unit is being specified by most chains. Hospitality Bedding Co. always suggests a 364 unit. This unit is the work horse of the bedding industry and simply does not wear out. As a point of fact, the 364 used to be Sealy's Posturepedic coil unit. Sealy wanted a coil unit that was proprietary so they now make their own.
  

• GAUGE OF THE WIRE - This refers to the thickness of the wire used. The lower the gauge the thicker the wire and conversely the higher the gauge the thinner the wire

• TYPE OF COIL - There are basically 3 types of coils: Bonnell, Continuous, and Offset.
  

• Don't confuse "soft" or "firm" with support. Your support comes from the coil unit.

• The final component to this set is the foundation or box springs. The purpose of the foundation is to help support the mattress by absorbing pressure thus helping to distribute body weight evenly. The proper foundation has a wood frame and properly tempered coils. An all wood foundation is available but since it does not have coils, it cannot help to distribute body weight. The mattresses lifespan is directly connected to the proper support it receives from the foundation. To understand this better think of the boxspring as a shock absorber. If the shock absorber is removed all the weight is transmitted directly to the springs of the mattress rather than being cushioned by the boxspring below. The mattress has to work twice as hard and is prone to wear out faster.

• The continuous coil system consists of coils formed from a single strand of 18 gauge steel wire strung through the system. This system gives a lot of support because of increased use of wire, even though it is 18 gauge wire.
  

• The Karr coil system consists of hour-glass shaped coils with the ends left unknotted. The hour-glassshaped coil offers a soft surface and firmness as pressure is applied. The offset coil configuration of the Karr coil means the coils are not totally round at the top and bottom. This shape is what gives the coils independent movement and reduces leaning by alternating offset from right to left.

• The Knotted Bonnell coil system consists of the hourglass shaped coils with five turns. It has a knotted end, making the surface firm.

• The Knotted Offset is similar to the Bonnell except that part of the top and bottom wire sections are squared off to fit together in a parallel fashion on the top surface. This hinge action also prevents leaning and sagging.

• The Marshall coil system consists of cylindrical coils sewn into a cloth or plastic pocket, so that they move independently of each other. The pockets keep each spring under tension at all times, thus reducing the tendency of the spring to spread when compressed. The Marshall system has a lot of coils. Since there are so many coils, very light wire is used to make the coils, around 18 gauge wire. This coil system is uncommon today, partly because of the high cost.

• My favorite mattress name encapsulates the paradox: Simmons Beautyrest World Class Granite Plush. Granite Plush???

• Larry Thomas of Furniture Today—a man described to me as "the guru of the bedding industry"—told me coil counts are "overrated" and "not a good indicator."

• Pillowtops: Pillowtops are soft layers of foam (or cotton, or wool) sewn to the top of the mattress. They're hugely popular. They add hundreds of dollars to your purchase. They are, in my opinion, a massive rip-off.

• Experts I talked to say thickness is just a ploy: It makes beds look comfy in the showroom. If you notice a difference, mazel tov, but thickness isn't vital to a good bed.

• Mattresses have gotten so thick recently that people are complaining they can't see their headboards. Actual industry response: They made the box-springs thinner. Which of course leads us to ...

• Box Springs: I find them wholly unnecessary. Think about it: Presumably, you could put a box spring under your box spring for even more "give" and "support." Another box spring under those two. Where do you draw the line?

• Many Europeans use platform beds without box springs. Do you hear them complaining?

• "Back pain has a lot to do with how you're built, but not a lot to do with your mattress."

• Do I Need All Those Extra Features? No. Screw 'em.

• Ticking and Quilting: People often buy based on how a mattress looks in the store. This is moronic. You're going to spread a sheet over it the second you get home. Belgian damask? Really, now.

• No-Flip Designs: Manufacturers say to flip your mattress every three months. It's even in some warranties. Yet this year's Simmons Beautyrest 2000 boasts a "no flip" design. And it's selling like hotcakes (for which flipping, incidentally, remains compulsory). Why? People love work-saving innovations—we're too lazy to flip. But what does it really mean? It means there's block foam on one side instead of something you could sleep on. And it means if there's a stain or a rip on the sleeping side, you're SOL. They should have called it the "can't flip" design. It's like a "No Oil Change" car that's simply had the dipstick and cap soldered in place.

• Select Comfort air mattresses... I didn't like the feeling of air, even though I could adjust the firmness with a remote-controlled pump. When you compress it with your weight, air doesn't seem to have as much give as foam. And it felt like I was camping.

• Remember: Once you're asleep, every mattress feels the same.
  

• Individual Pocket Coil - Considered the most conforming coil. Gives a mattress a very "quiet" feel. This coil produces the least amount of motion when someone else sits or lies on the bed. Coil counts range from 580 to 704.
  

• Continuous Coil - Each row of coils is made up of one continuous wire, rather than each coil being a seperate wire. Considered a firm, yet individually conforming coil. The firmest coils Leggett & Platt makes are constructed this way. Coil counts range from 442 to 755.

• Offset Coil - Each coil is oval in shape lapped over the coil in the next row. Considered a firm, yet individually conforming coil. Coil counts range from 368 to 680.

• Bonnell Coil - Classic "hour glass" shaped coil found in most basic bedding. Coil counts range from 210 to 364

Mattresses (Wikipedia entry)

Types of coils

There are four different 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, also called "pocketed coils," are each wrapped in a fabric encasement and usually are tempered, or in the case of the Simmons Beautyrest carbon magnesium is added. Some manufacturers pre-compress these coils, which makes the mattress firmer and allows for motion separation between the sides of the bed.
• 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 and up and down fashion forming one row (usually from head to toe) of what appear to be invidiual coils. The advantages of how firm a support the continuous coil provides is somewhat tempered with the 'noise' associated from a typical mira coil unit.

• # 4,488,712 - Longitudinally laced continuous coil spring assembly
• # 4,766,624 - Mattress assembly having rows of coil springs formed from a single continuous length of wire
• # 4,766,625 - Box spring having rows of coil springs formed from a single length of wire
• # 4,771,494 - Offset continuous row coil spring assembly
• # 4,790,038 - Bedding spring assembly
• # 4,982,466 - Body support system (air mattress)
• # 5,127,635 - Pocketed continuous wire multiple coil spring bedding product
• # 6,260,223 - Pocketed coil spring units

LOL!   This thread is a good short primer. 

Here's another guide and it also discusses foundations a little:  http://extension.usu.edu/files/publications/factsheet/HI_08.pdf

Here's another, more global, perspective:    http://www.mattressinside.com/orthopedic.html