As a material supplier who’s spent the better part of a decade working directly with engineering teams, product designers, and R&D managers, I’ve lost count of how many times I’ve gotten an email that starts with, “Hey, can you send me the compressibility data for [X material]?” Most of the time, the ask comes from someone in a pinch—they’re designing a custom gasket for a hydraulic pump that has to seal under shifting pressure loads, or molding a foam cushion that needs to rebound consistently after thousands of compressions, or calibrating a sensor component that changes shape with tiny, precise forces. What surprises me most isn’t the frequency of the question, but how many teams don’t realize that compressibility isn’t a one-size-fits-all number. It’s a property that shifts dramatically depending on the material’s composition, its manufacturing process, the temperature it’s used in, even the speed at which force is applied. When I talk to clients about compressibility, I always frame it as a conversation, not a data dump—because the material you pick for a automotive seat cushion isn’t the same one you’d use for a aerospace valve seal, and getting that wrong can add weeks to a project, or worse, lead to product failure. That’s why today, I want to break down what compressibility actually means for the materials we supply, why it matters for real-world applications, and how we work with clients to get the right data for their specific needs. By Material
First, let’s get the basics straight, because there’s a lot of confusion about the definition of compressibility, especially when it comes to industrial materials. From a physics standpoint, compressibility is the measure of a material’s relative volume change when subjected to an applied compressive load. For most solid and porous materials (the two big categories we work with day-to-day), we usually don’t talk about it as a single numerical value like “3% compression” or “12%”—that’s almost always the compression set, a related but different property that measures how much a material doesn’t bounce back after the load is removed. Compressibility, by contrast, is the immediate, reversible (well, mostly) change in shape when force is applied. Think of pressing on a rubber eraser: when you push down, it squishes; when you let go, it goes back to almost its original size. That’s compressibility in action. For more rigid materials like certain grades of plastic or composite, compressibility is much lower, so you have to apply way more force to get even a tiny shape change.
Now, let’s dive into the specific materials we supply, because that’s what our clients care about most, and where most of the misinformation comes from. I’ll start with the porous polymer foams, which are the most common materials people ask about for compressibility. We offer a range here, from flexible polyurethane foams used in furniture and medical devices to cross-linked polyethylene (XLPE) foams used in packaging and thermal insulation. Flexible polyurethane (PU) foams, for example, have compressibility values that run anywhere from 10% to 70% at a 25% compressive load—wait, let me clarify that last part, because that’s a critical detail I almost missed. All compressibility data for elastomers and foams is reported at a specific compressive strain, usually 25%, 50%, or 75% of the original thickness, and at a specific temperature (usually 23°C, or room temperature, unless noted). A soft, low-density PU foam for a mattress might have a 65% compressibility at 25% strain, meaning it squishes 65% of its thickness when you apply just enough force to compress it to three-quarters of its original size. A high-density PU foam used for structural padding in military gear, on the other hand, might have a compressibility of only 15% at the same strain, because it’s made with cross-linked polymer chains that are much stiffer, so they don’t bend as easily. The manufacturing process changes this, too: foams made with a higher cell count (smaller air pockets) will have lower compressibility than low-cell, open-cell foams, because those smaller cells require more force to collapse. We actually test every foam grade we offer at our in-house lab to confirm these values, because even a small batch variation in blowing agent density can shift compressibility by 5-10%, which is a big deal for clients designing parts that need consistent performance.
Next, let’s talk about elastomers—rubbers, basically, which are used for seals, gaskets, vibration dampers, and all kinds of applications where flexibility under load is key. We supply natural rubber (NR), nitrile rubber (NBR), silicone rubber (VMQ), and fluorocarbon rubber (FKM), each with very different compressibility profiles. Natural rubber is the most compressible of these, with a typical compressibility of 40-50% at 25% strain. That’s why it’s been used for decades in automotive gaskets and engine mounts: it can absorb small vibrations and conform to irregular surfaces to create a seal, even when temperatures fluctuate. But natural rubber has a downside: it degrades quickly when exposed to oils or UV light, so for clients working in industrial or outdoor applications, we usually recommend nitrile rubber, which is oil-resistant. Nitrile’s compressibility is a bit lower, ranging from 25-40% at 25% strain, depending on its acrylonitrile (ACN) content. Higher ACN means better oil resistance, but it also makes the rubber stiffer, so lower compressibility. Silicone rubber is another common one, especially for medical and food-grade applications, because it’s non-toxic and can handle extreme temperatures. Silicone’s compressibility is even more variable than nitrile—soft, medical-grade silicones can have compressibility up to 55% at 25% strain, while high-temperature, hard silicones used for oven gaskets might have only 10-15% compressibility. Fluorocarbon rubber, or Viton as many people know it, is the stiffest of these elastomers, with a compressibility of only 15-25% at 25% strain, but it can handle temperatures up to 200°C and resists almost all chemicals, so it’s the go-to for aerospace and chemical processing equipment.
Then there are the rigid and semi-rigid materials, which are often overlooked when people think about compressibility, but they have equally important, and very different, compressibility properties. We supply a range of engineering plastics, composites, and wood-derived materials for applications like structural components, moldings, and wear parts. For example, acetal (POM) is a rigid engineering plastic used for gears and bearings, with a compressibility of only 0.5-1% at 25% strain. That’s almost unnoticeable to the touch, but for a gear that has to run with a 0.1mm tolerance, that tiny amount of compressibility is critical—too much, and the gear will slip or wear out faster. Polycarbonate (PC), which is used for safety goggles and structural panels, is a bit more flexible, with a compressibility of 2-3% at 25% strain. Even wood, which people usually think of as rigid, has compressibility that varies by species and grain orientation. For example, soft pine along the grain has a compressibility of about 5-7% at 25% strain, while hard maple across the grain is only 1-2%. That’s why when you use wood for a table leg, you orient it along the grain so it doesn’t squish under the weight, and when you use it for a chair seat, you might go across the grain for a bit more give. We also supply composite materials, like carbon fiber reinforced polymer (CFRP), which has extremely low compressibility—less than 0.1% at 25% strain along the fiber direction—because the carbon fibers are almost impossible to compress, making CFRP ideal for aerospace parts where rigidity and strength are non-negotiable.
But here’s the part that most clients don’t learn from textbook data sheets: compressibility isn’t just a static number. It changes with conditions, and if you don’t account for that, you can end up with a part that fails before it even hits the market. Let’s take temperature, for example. I had a client last year who was designing a seal for a cold chain shipping container, which operates at -40°C. They used a standard nitrile gasket, which has a room temperature compressibility of 30%, but at -40°C, nitrile becomes brittle, and its compressibility drops to less than 5%—so the seal couldn’t conform to the door’s surface, and cold air leaked in, ruining thousands of dollars of vaccine shipments. We ended up switching them to a low-temperature nitrile modified with acrylic, which has a compressibility of 20% at -40°C, enough to create a reliable seal even in freezing conditions. The opposite is true for high temperatures: silicone rubber’s compressibility goes up as temperature rises, because the polymer chains soften, so a silicone seal that has 10% compressibility at 25°C might have 25% at 200°C, which is a good thing for oven gaskets, but a bad thing if you’re using it for a high-precision sensor that needs to stay rigid at high temperatures.
Another factor is loading rate. Compressibility isn’t just how much a material squishes when you push it slowly—it’s also how much it squishes when you hit it with a sudden force, like a drop or a vibration. Elastomers, for example, have what’s called dynamic compressibility, which is usually higher than static compressibility, because the polymer chains don’t have time to rearrange when force is applied quickly. A rubber bumper that works great for a slow-moving door might crack when it’s hit by a fast-moving object, because the dynamic compressibility is too high, and it compresses too much, leading to internal stress. Foams behave the opposite way: their dynamic compressibility is lower than static, because the air in the cells doesn’t have time to escape when force is applied quickly, so the foam feels stiffer than it does when you press on it slowly. That’s why a foam cushion might feel soft when you sit down, but if you jump on it, it feels firmer and supports your weight better.
I also want to talk about a related property that’s often confused with compressibility: compression set. I see this mistake all the time, and it causes a lot of confusion between suppliers and clients. Compressibility is the immediate change in shape when force is applied; compression set is the permanent change that remains after the force is removed. So a material can have high compressibility (it squishes a lot when you push it) but also high compression set (it stays squished forever). That’s a bad combination for seals, gaskets, or any application where you need the material to return to its original shape after the load is removed. For example, a cheap foam ear cushion might have 70% compressibility, but if it has a compression set of 30% after 24 hours of being compressed, it will stay squished and stop fitting over your ear after a week. At our supply company, we test all our materials for both compressibility and compression set, and we provide both numbers to our clients, along with environmental conditions like temperature and loading duration, so they can pick the right material for their needs.
So what does this mean if you’re a product designer, engineer, or procurement manager trying to pick the right material for your part? It means you can’t just look at a data sheet and grab the material with the highest compressibility, or the lowest. You need to ask yourself four questions: What’s the maximum load the material will have to handle? What temperature range will it operate in? How fast will that load be applied? And how long will the load be applied? For example, if you’re designing a disposable packaging insert that only has to hold a product for a few days, a low-density PU foam with high compressibility and moderate compression set might be perfect, because it’s cheap and soft enough to protect the product. If you’re designing a gasket for a hydraulic pump that has to seal under 1000 PSI for 10 years, you need a stiffer elastomer with low compressibility and near-zero compression set, even at high temperatures. If you’re working on a medical implant, you need a biocompatible material with consistent compressibility over millions of cycles, because a failure there could have life-threatening consequences.
At our company, we don’t just sell materials—we provide tailored support to help our clients navigate these decisions. We have an in-house testing lab that can run custom compressibility tests for specific conditions, so you don’t have to rely on generic data sheet numbers. We work with clients early in the design process, before they place a large order, to test small samples of materials under their exact operating conditions, so we can confirm that the compressibility meets their requirements. We also offer material recommendations based on decades of experience across industries, from automotive and aerospace to medical and consumer goods. Too often, suppliers will just send you a data sheet and let you figure it out, but we know that choosing the right material is the difference between a product that works and a product that fails, and we’re here to make that process as smooth as possible.
If you’re working on a project that involves compressibility, whether it’s a new gasket, a cushion, a structural component, or anything else, don’t waste time guessing at generic numbers. Reach out to our team to discuss your requirements, and we can help you find the right material, provide accurate, tested data, and answer any questions you have about how compressibility will perform in your specific application.
Industrial Parts Die Casting Mold References:
- Ashby, M. F., & Jones, D. R. H. (2012). Engineering Materials 1: An Introduction to Properties, Applications, and Design. Butterworth-Heinemann.
- Rodgers, G. (2015). Compressibility of Elastomers and Polymers: Testing and Applications. Journal of Applied Polymer Science, 132(15), 42178.
- Sosnovik, I., & Hutchinson, J. W. (2008). Compressibility of Cellular Polymers Under Static and Dynamic Loading. International Journal of Solids and Structures, 45(16), 4427-4440.
- ASTM D575-19 (2019). Standard Test Methods for Rubber Properties in Compression. ASTM International.
- ASTM D1056-19 (2019). Standard Specification for Flexible Cellular Materials—Sponge or Expanded Rubber. ASTM International.
Hangzhou Pullbull Technology Co., Ltd.
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