Silica and fiberglass are two terms that have become very intertwined in the mattress world during the last few years. This guide will show you how to differentiate between the two terms and sift through some of the misinformation that has been spread around the internet regarding fiberglass in mattresses.
About Fiberglass and Silica
To start off, let’s look at the two terms as a whole and learn exactly what both of them actually mean.
About Fiberglass
Fiberglass is a broad term that encompasses many types of glass-reinforced fibers. The most common type of fiberglass is a silica-based glass fiber that is coated in a resin. The resin is most often made of polyethylene terephthalate (PET), also known as polyester. Because of this, fiberglass is also known as glass-reinforced plastic, since polyester is technically a plastic.
Fiberglass is also mixed with even larger amounts of resin to form rigid shapes such as boat hulls, fence posts, and things like exterior patio furniture. Because fiberglass is flame-resistant, it is also used as insulation in the walls and attics of homes without being a fire hazard.
About Silica
Silica is a general term for a naturally occurring mineral found in nature, its technical name is Silicon Dioxide. It’s most often found in the form of silica sand, quartz, and opal, but is also found in some grasses and the skeletons of sea sponges. The two main forms of silica are Crystalline Silica and Amorphous Silica.
Silica in its crystalline form is used as an ingredient of cement, as well as ceramic pottery. Silica is also the main ingredient of silicon, which is the main material in electronic circuit boards and semiconductors. Because it’s used to make glass, Silica can also be found in the fiber optic cables used in telecommunications as well as fiberglass.
Silica in its amorphous form is used as an anti-caking agent in some foods and cosmetic products. It’s also used in the brewing of certain alcoholic beverages. Silica is even used as a mild abrasive in some toothpaste.
The Difference Between Fiberglass and Silica
Fiberglass, compared to silica, is a very narrow term that mainly refers to continuous-strand glass fibers. Although fiberglass is used in many different ways, the fiberglass itself is mostly the same. Fiberglass is a mucous membrane irritant of the eyes, nose, mouth, and throat; and it may increase irritation of the lungs in bronchitis and asthma sufferers. Prolonged contact with fiberglass causes skin irritation and can lead to fiberglass dermatitis.
In comparison, silica is a very broad term that encompasses many different types of material under the two main sub-categories of Crystalline Silica and Amorphous Silica. It comes in many different forms and is an ingredient in many products across varying industries. In its crystalline form, silica can cause silicosis of the lungs, however, the amorphous form of silica is harmless in comparison.
How Fiberglass is Used in Mattresses
Fiberglass in mattresses is often used in the form of core-spun glass fibers that are sheathed in another material like polyester or rayon. The composite glass fiber is then woven into a fabric and made into a fire-resistant inner cover that encases the foam inside a mattress. This inner cover acts as a flame barrier and is known in the mattress industry as a “firesock”.
However, there are some exceptions to fiberglass being used as just a firesock. During the Zinus lawsuit of 2020, it seemed that Zinus mattress had loose fiberglass particles spread across the top layer of its memory foam that was held in place by the inner cover. Until recently, SweetNight was using fiberglass-embedded memory foam for its mattresses.
How Silica is Used in Mattresses
Silica is most often found in mattresses by the use of Inherently Fire-Resistant Rayon. Rayon is a textile made from wood and plant fibers that have been dissolved in chemicals and then reconstituted as a fiber using different chemicals. During the rayon-making process, Amorphous Silica can be added to the pulp of dissolved plant fibers, and the resulting fiber will be inherently flame-resistant. This fabric is also referred to as FR Rayon as well as Visil Rayon.
Another way silica is used in mattresses is through the use of Hydrated Silica powder. It is made by dissolving silica with soda ash and water, then dehydrating the resulting mix and chopping it into a powder. Hydrated silica is the type of silica that’s FDA-approved for food and cosmetic use, it’s also used as a flame-resistant textile treatment in mattresses.
Silica found in mattresses can also be in the form of continuous filament silica used within a woven textile inner cover acting as a flame barrier, much like fiberglass. However, true woven silica fabric is much more expensive than fiberglass fabrics, so most mattress makers just use fiberglass or Inherently FR Rayon.
The Problem with Silica and Fiberglass Fibers in Mattresses
Both Silica and Fiberglass textiles are brittle. If the fibers are exposed to extreme force, the fibers can break and crumble. Even extended periods of normal use can wear down the integrity of the fibers and cause them to break down into smaller pieces. When a mattress’s outer cover is removed, or has a hole, the fiberglass and silica inner covers break down at a rapid pace.
Once the Silica or Fiberglass particles have broken down into finer strands, they can be shed through a mattress’s outer cover by literally just poking through it. Most of the horror stories about fiberglass contamination that went viral on social media involved the removal of the mattress cover for cleaning. Many online reports of mattresses leaking fiberglass and silica state the outer mattress cover was never removed, however, and the fiber particles are simply slipping through the cover.
Some Mattresses Makers Disguise Fiberglass as Silica
Sure, there might be some mattress makers that actually use silica fabric instead of fiberglass. I assume that mattress makers actually using the more expensive silica fabric would be proud, and they’d freely share it with consumers as a selling point. The problem is that many mattress makers that say they use silica don’t actually have proof that it’s not just fiberglass.
Fabric that’s truly made of silica, and not fiberglass, may not be as potentially harmful as fiberglass. However, silica fabric can still break down and shed fibers that leak from mattresses and contaminate your living area. So, even though true silica fabric is safer than fiberglass, it’s still not the best choice when it comes to flame-resistant barriers in mattresses.
This is where the mattress brands’ deception starts. Instead of removing potentially harmful fiberglass from their mattresses, many mattress makers just began saying their glass fiber is actually just Silica. Mattress makers can get away with saying fiberglass is silica since fiberglass is mostly made from silica, and there are no laws or regulations preventing them from deceiving consumers.
Mattress Brands That Use Hydrated Silica or FR Rayon
These brands of mattresses use Inherently FR Rayon that has Silica added during the manufacturing process, or fabric that is treated with Hydrated Silica powder.
Mattress Brands Using “Silica” Thread, Potential Fiberglass
These brands of mattresses say their flame barrier is silica, but they provide zero proof that the fabric is just silica and not fiberglass in disguise.
Other Mattress Terms to Avoid like Fiberglass
Since the fiberglass lawsuits and contamination horror stories shared on social media, many mattress makers have started using “alternative” names for their fiberglass to make it seem less scary.
These are some terms to look out for:
- Continuous Filament Fiber – This could refer to continuous filament silica fiber or continuous filament glass fiber.
- Core-Spun Glass Fiber – A term used by many mattress makers, it just means glass fiber that’s been wrapped with a different fiber like rayon or polyester.
- Silica and Polyester Blend – Since Fiberglass is made of silica glass and polyester resin, many mattress makers hide their Fiberglass by calling it a blend of silica and polyester.
- Filament Poly – Filament Poly can refer to continuous filament polyester thread, but it’s also a clever way to say glass filament core-spun polyester.
- GRP/GFRP – These are abbreviations for Glass Reinforced Plastic, and Glass Fiber Reinforced Plastic, which are both terms for fiberglass.
- Vitreous Fiber – This is another term for fiberglass.
- Glass Wool – This is another term for fiberglass.
- Fiber Reinforced Plastic – This can refer to many different fibers that are reinforced with a plastic resin, fibers such as Para Aramid (Kevlar) and Carbon Fiber, but it can also refer to fiberglass.
Last Updated on February 18, 2024
While shopping for his daughter’s first “big girl” bed in 2019, John learned about the hidden dangers of fiberglass in mattresses. Since then, he’s made it his mission to expose as much hidden fiberglass in mattresses as possible. His ultimate goal is federal regulations that ban fiberglass from being used in mattresses, or at least a law that requires it to be listed as a material on required tags.
What about this….
The fire-retardant sock on the mattress is made of a blend of cotton and Rayon, which is extracted from bamboo. There are generally 2 types of Rayon, and one is called Visil Rayon, which has silica in it. Silica is another word for sand. It doesn’t feel sandy, as you can tell, so this is mostly there at the molecular level. Anyway, the combustion temperature of Silica is higher than the temperature that the average flame burns at, and this allows the bamboo and cotton cover to act as a natural fire barrier for the mattress so that we don’t have to use any chemical flame retardants.
Again good or bad??
Thank you for explaining
We need you tube videos about this topic asap
I did have a purple 4 ..I was always sick I develop allergies like crazy
Visil Rayon is another name for FR Rayon, which is exactly what that explanation says it is. When the plant fiber/cellulose is dissolved with acid, silica is added to the cellulose before it’s reconstituted back into a solid in the form of rayon. This makes the rayon inherently fire-resistant without using glass fiber.
Hi, thanks for a nicely written and well-researched article!
I wonder if you can help. I’ve been trying to find out the fiberglass component of the Peace Lily Hybrid Mattress and the Ecosa Pure Mattress (also a hybrid).
Peace Lily has a strong brand positioning around being eco friendly and sustainable and healthy, and push all the certifications they have (e.g., ECO Institut, Oeko-Tex Standard 100, etc.). Their Hybrid mattress has GOTS certified cotton for the cover and wadding and 100% Dunlop latex enclosing the coils. They say the mattresses contain no chemical flame retardants and that they are generally resistant to fire, but not completely fire-resistant. I cannot find anywhere whether they use non-chemical flame proofing materials (like fiberglass). I’m under the impression that natural latex is far less flammable than polyurethane foams and so perhaps they don’t have any additional fireproofing. In your research, have you gathered information about Peace Lily mattresses, especially the Hybrid?
The Ecosa Pure Mattress has a mix of Dunlop and Talalay latex (there’s conflicting info on polyurethane foam) sandwiching coils and springs. The website prominently states it is “completely free from fiberglass” and this was confirmed by a CSR. I asked for a list of anything they used for fireproofing, and the CSR emailed me later with, “As confirmed by our team, only our Ecosa mattress has a fire-resistant feature. Therefore, we can guarantee that the Pure Mattress is completely free from fiberglass. Moreover, the Ecosa mattress’s foams are encased in a fire-resistant sock. The FR sock is made of 96% cotton and 4% polyester with FR treatment. The additive used for the FR treatment of the fabric is Argafun P-NT.” I think they’ve said the Pure Mattress doesn’t have this sock but have tried searching for this treatment anyway and found very little. Have you come across it but it hasn’t made it onto your website (maybe it’s a different name for something that you have written about)? Have you found in your research that the Ecosa Pure Mattress doesn’t use fiberglass?
I’d greatly appreciate anything you could share about either. Also on the Emma Comfort Mattress specifically, which I am pretty sure must have fiberglass but I cannot find much info.
Thank you for all the effort you’ve put into this site.
Peace Lily claims to only use wool as its flame retardant. This is fairly common among latex mattresses, since latex is slightly less flammable than memory foam, so I’m inclined to believe them.
Ecosa hasn’t given me much info the times I got in touch either, however, I was in contact with their New Zealand branch since glass particles leaking from NZ mattresses is now a thing. As for Argafun P-NT, I couldn’t find an exact match. Argafun seems to be a chemical maker out of China, and P-NT seems to be short for Para-Nitrotoluene, which looks like pretty nasty stuff.
Emma used to state its flame barriers were silica and modacrylic here in the US, but modacrylic is pretty bad stuff while “silica” is often just a cover for glass fibers. There are reports around on the web of Emma mattresses making customers itchy. However, more recently it started saying the flame barriers are Rayon and Acrylic. Rayon and Acrylic aren’t exactly Fire-resistant materials, so either the Rayon is FR Rayon that contains silica, or the Acrylic is actually still Modacrylic. I don’t know for sure, because Emma refuses to give more information! Nice!
I have had a lab test the fibers coming from my upholstered bed frame and an elevated presence of fiberglass was found
The label states : Compliance with California flammability requirements
Polyurethane foam pad 100%
Covering : Polyester 100%
Supply chains in China change all of the time, any chance you know of any fiberglass or silica fibers in these materials?
The glass did not blow in through an open window.
Bed frames aren’t held to the same CFR 1632 and 1633 flammability standards as mattresses, so it’s more likely that the fiberglass on the bed frame has shed from a mattress that was on the bed frame rather than the bed frame itself. Hope this helps.
I have a 2010 sleep number bed. A tag has silica fiber listed. There is a thin canvas like cloth that borders the outer cushions stating it needs to be in place for flammabity protection, which I believe is the silica fiber. If this cloth was cut, would it shed glass pieces and cut like fiberglass? Thank you.
Silica Fiber could be code for “glass fiber”, you sadly never know these days. The flame barrier is probably an inner-cover that’s underneath the canvas-like outer cover.
Whether it’s actually silica, or glass fiber, it could definitely shed and contaminate your home. If it’s indeed just silica thread, it probably wouldn’t be as much of an irritant as actual fiberglass, but it would still be a hell of a nuisance.
If the fiber is brittle and crumbles easily, it’s most likely glass fiber and not silica.
So does Zinus still use fiberglass? They seem to be selling pretty well still.
Zinus actually stopped using fiberglass recently. You can read more bout it here – https://fiberglassfree.com/guides/does-zinus-still-have-fiberglass/