We have all seen the bowling ball drop and the independent coil claims. However, when I look at the construction of pocket coil mattresses, they are all glued together and then manufacturers glue a foam top piece to the pocket coils. Does this undo the benefits of independent pocket coil springs in terms of disturbing my partner while sleeping? I toss and turn a lot and so this becomes an important feature in my mattress selection. Thank you
Hi cook7renter,
Welcome to the Mattress Forum! 
To show you the power of advertising, I don’t think that “bowling ball” commercial has run on a national ad campaign in over a decade!
Regarding spring units, pocketed springs by themselves will tend to be the best at “motion isolation” and working as independently as possible. The springs are wrapped by fabric, and then the fabric is usually glued together with 2-3 rows of glue near the middle of the springs, starting about ¼ of the way from the top of the springs. This allows the springs to move a bit more independently before being impacted by compression of the spring next to them than if they were tied together on the top with helical lacing.
Some manufacturers glue a thin layer of nonwoven material on the top and the bottom of these spring units in place of gluing them together in between rows in the middle of the springs, and some manufacturers will do this in addition to gluing them in the rows in the middle of the springs.
Gluing padding layers on top of these pocketed spring units tends to be done mostly around the perimeter and is more for holding the foam in place. Gluing directly on top of the springs tends to be lighter, if at all, as it can be noisy as the glue bonds break when the bed is newer. The impact this will have upon the spring unit moving “independently” will be based upon the type of foam used.
Pacing these layers on top of the spring unit can impact overall motion isolation, but a pocketed spring unit will still be the best at motion isolation of the major spring types (LFK, Bonnell, continuous coil, knotted offset).
Overall, there are variables between each material, between combinations of materials and components, and between the type of movement you are trying to isolate (larger bouncy movements, smaller vibration type of movements etc.) and the effect of comfort layers (latex, memory foam, microcoils) compared to the effect of support layers (latex, innersprings).
Comfort layers will have more of an effect on smaller or slower movements or can damp the effect of the layers below while support layers will have more of an effect on larger, stronger, or faster movements. There are also different types of each material and different mattress constructions that can have more of an effect than the material itself.
For example … memory foam is a much more energy absorbing material and is also very point elastic (conforms to the shape of the body more exactly, at least if it’s good memory foam) and would typically be the “best” at motion isolation. But if you put memory foam on top of an innerspring that has helicals then you would still feel the stronger or faster movements that went “through” the memory foam and compressed the springs (here the pocketed springs would be better, whether or not there were foam layers glued to the top of it). In the same way if you had a memory foam comfort layer and then had a quilted cover that didn’t have any stretch you may feel smaller movements more because the cover would “pull” when you moved … especially if someone was heavier.
Latex, like memory foam, is very point elastic which means that it compresses at millions of specific points across the surface to take on the shape of the body profile with much less effect on the area around the point of compression but it is also highly resilient which means it absorbs much less energy than memory foam which has little to no resilience at all. If you throw a ball at memory foam attached to a wall it will just drop to the floor while if you throw a ball against a wall with latex it will bounce back.
As a comfort layer memory foam would be “excellent” and latex would be “good”. As a support layer memory foam isn’t used so it can’t be included in a comparison with other support materials and I would rate springs that use helicals as “poor to fair” depending on the type of spring, and pocket coils (which don’t use helicals and compress more individually) and latex as “good”. Polyfoam is also generally good at motion isolation.
Box springs under a mattress or other support systems that flex under a mattress can also transfer more motion than a support system that has no flex at all. Traditional metal bed frames also commonly have some movement and tend to be bad at helping to isolate motion.
All of this would be subject to the specifics of the overall mattress construction and the sensitivity and sleeping style of the people on the mattress which may have just as much of an effect as the material itself. This is why you will see some people saying they can feel their partner’s movement on a certain mattress when large numbers of people say they feel nothing at all.
Different people are more sensitive to different types of movement and different mattress constructions will have different overall effects on motion isolation so testing a specific mattress is usually the best way to know with the caveat that memory foam will tend to improve motion isolation more than other materials regardless of the type of construction.
Phoenix
Thank you for the information. Your information was very helpful. I would have sworn that it had not been that long since I saw that commercial but time does fly.
Eric
Hi cook7renter,
It’s possible they brought the commercial back in a newer version in your area, but like you, I can remember that commercial like I just saw it on TV yesterday. One of the most successful ad campaigns in the mattress industry ever.
Phoenix