Silica safety

Hi, I’ve searched the site and forum and can’t find any detailed discussion about the safety of rayon/silica products to meet flammability regulations.

Does anyone know whether there is any indication the silica can become airborne? And if so, are the particles large enough that an allergy barrier will contain them?


Hi wmorris,

There is a mention here of the rayon/silica fire barriers.

This seemingly brief few paragraphs was actually the conclusion of many hours of research into fire retardant materials and for those who go in this direction … it quickly becomes clear that there is a huge amount of misinformation on the web about fire retardancy and all the different methods used to accomplish it. Just a brief synosis to help with ideas for google searches for those who want to do their own research as well …

Silica (silicone dioxide) comes in several forms … but the two main ones are amorphous and crystalline. The crystalline form is the one which is of concern for silicosis. The amorphous form is of low toxicity even when inhaled. In addition to this … the fire retardant materials such as Visil (which uses sandoflam 5060) and Milliken’s Paladin (trade names) uses silicic acid (or polysilicic acid) which is actually mixed in with the viscose and its precipitate becomes an integral part of the fiber itself rather than a “powder” that is added to it. This is why it is called inherent and it is actually a cellulose-polysilicic acid hybrid fiber.

I find it somewhat ironic that some of the “natural” community who confuse the dangers of amorphous silica and crystalline silica also would advocate for the use or more natural pesticides such as diatomaceous earth which is actually a partly crystalline version of silica and carries a far higher risk than the inherent fibers in a mattress.

While I am no fan of the fire regulations or of many of the chemicals used (some of which are no longer used) … I also believe that sites such as the Strobel site which presents some completely inaccurate and misleading information about some of the better and safer fire retardant methods (such as wool and silica) are also responsible for much of the confusion regarding fire retardant issues.

IMO … I wouldn’t hesitate to use either wool or rayon/silica for a fire barrier in a mattress without any worry of danger or toxicity.


I have been talking to intellibed and they offered to recover a demo model and eliminate the silica flame retardant layer for me. Is this really significant? All things being equal I would probably opt for a new one, but this one was only used 4 days and they will recover it and eliminate the silica/yarn layer. I’m also wondering if the yarn layer is polyester, which also has problems.

In the FAQs on the Intellibed website, the company identifies its FR barrier as “A silica based fire blocker with a modacrylic fiber and no bio available chemicals. It basically goes on the bed like a sock.” The silica is the amorphous form Phoenix referred to back in 2012. The FR solution is classified as an inherent version as the silica is added in the fiber manufacturing process so the material becomes a form similar to the cellulose-polysilicic acid hybrid fiber that Phoenix identified. The “FR Sock” that intellibed describes is the most commonly used FR barrier in the US mattress industry. This fabric sock material allows for mattresses with components that have lower levels of “flammability” to comply with 16 CFR 1633. As an inherent solution, it poses no health risk. Suppliers of FR barrier materials to the US mattress industry have made significant advances in their material technologies over the past 10 years, reducing costs and improving the safety and health benefits.

The question you need to ask intellibed is “What will the FR solution be ?” that will be used if they eliminate the FR sock from your demo model. They are required by law to sell you a mattress that meets the CPSC FR standards (provided you are in the US).

The yarn is most likely a viscose rayon or an acrylic.

Hi Luma Sleep,

From what I’ve read and researched, it seems modacrylic has become a “dirty” term in the industry and isn’t considered very “healthy” in general as it normally contains antimony at the very least. I’d be interested to get your insights on it and was also wondering if many of the inherent socks use it, though perhaps leave the term out and just mention inherent rayon and/or silica.


So there isn’t really an issue with this type of barrier “flaking off” or becoming airborne in terms of how its made? and probably no more than any other type of furniture fibers? Just curious. It does seem like this, beside wool, is a good option.