The All-Foam Paradox: Why a "Medium Plush" Mattress Can Feel "Firm" (And How to Fix It)

You’re shopping for an all-foam mattress and find one with over 29,000 reviews. The description says “Medium Plush.” You dive into the reviews, and chaos ensues.

• One 185-lb reviewer compares it to a Sleep Number of 65-70, calling it a perfect “medium firmness.”
• Another reviewer says it’s a “perfect happy medium… firm yet soft.”
• But then a 115-lb reviewer says: “this mattress feels firmer than it would… to someone of average body weight.”

How can this be? How can a “Medium Plush” mattress feel firmer to a lighter person?

This isn’t a contradiction; it’s the All-Foam Paradox. The feel of a multi-layer foam mattress is not a single number; it’s a complex, engineered system. Deconstructing a popular 4-layer model, like the Novilla 12-Inch Gel Memory Foam Mattress, shows us exactly why this happens.

The 4-Layer System: A “Firmness” Sandwich

An all-foam mattress is not one single block. It’s a “sandwich” of foams with different densities, stacked to create a progressive firmness. A 12-inch, 4-layer system is typically built like this:

1. Layer 1 (The “Plush”): Gel-Infused Memory Foam. This top layer is soft. Its job is to provide “pressure relief” and that “cloud-like” feel.
2. Layer 2 (The Transition): “Egg Crate” Foam. This is a convoluted (wavy) layer. Its job is twofold: to allow airflow (for cooling) and to act as a transition between the soft top and the hard bottom.
3. Layers 3 & 4 (The “Firm”): High-Density Foam Core. This is the “support.” These two bottom layers are the firm, heavy-duty foundation that “resist sagging” and “prevent roll-off.”

This is the engineering. Now, let’s see how it interacts with different body weights.

The Weight Paradox: Why a 115-lb Person Feels “Firm”

Here is the counter-intuitive part.

• For an Average/Heavier Sleeper (180-200+ lbs): Your body weight is sufficient to sink through the soft top layers (Layer 1) and be “caught” by the plush “egg crate” (Layer 2) and the firm high-density core (Layers 3 & 4). You are experiencing the full system as intended, which feels like a “perfect happy medium.”
• For a Lighter Sleeper (< 115 lbs): Your body weight is not enough to significantly compress the top layers. You “float” on top of the mattress. You never sink deep enough to activate the “plush” contouring of the memory foam. Instead, you are primarily resting on the top of the transition and support layers, which, as the reviewer correctly noted, “feels firmer.”

This is the opposite of a hybrid spring mattress, where a light person only feels the soft top. On an all-foam bed, a light person may only feel the top of the firm support system.

The Two Unavoidable Trade-Offs of “All-Foam”

This engineering leads to two compromises that you must know before you buy.

1. The Edge Support

One reviewer put it perfectly: “edge support is absolutely not on par with a traditional mattress.” This is a 100% accurate and unavoidable trade-off. An innerspring (hybrid) mattress has a steel perimeter. An all-foam mattress does not. If you sit on the edge to put on your shoes, you will find “you’ll have to adjust.” This is a key feature of all-foam mattresses, not a defect of this specific brand.

2. The Foundation (The “Secret” Failure)

A 200-lb+ user left a brilliant 5-star review with a critical warning. He felt a “slight dip” in the mattress and thought it was failing. Then he did some research: “I decided to throw 1/2” inch plywood in between mattress & box spring which totally fixed the problem. The dip feeling was being caused by the box spring not the mattress.”

This is the most important piece of advice for any all-foam mattress: You cannot put it on a traditional “spring fitted” box spring. A box spring is designed to flex. A foam mattress requires a solid foundation. You must use a platform bed, solid slats, or, as this user did, a piece of plywood over your old box spring.

The Cooling System: An “Egg Crate” and Bamboo

Finally, the “foam sleeps hot” problem is a real one. The Novilla mattress attacks this with three features:
1. Gel-Infused Foam: The gel helps absorb and distribute heat away from your body.
2. “Egg Crate” Airflow Layer: This convoluted layer is not just for comfort; it’s an “air channel” designed to let hot air escape.
3. Bamboo Fabric Cover: The cover is made with “Bamboo fabrics,” which are naturally breathable and known for wicking moisture, enhancing the “30% breath-ability.”

As one user noted, this system isn’t magic (“warm sleepers are still going to find themselves sleeping warm”), but it is a powerful combination that, for most, creates a “cool and comfortable” sleep.

When you buy a “Medium Plush” all-foam mattress, you are buying a complex 4-layer machine. Its “feel” will depend entirely on your body weight, and its performance will depend entirely on the foundation you put it on.