Hey Looking4mattress. Interesting question.
As you are aware, wool is often used in mattresses for its natural fire resistance properties. The thickness of the wool batting can affect its ability to provide fire resistance. Generally, thicker wool layers might provide better fire resistance due to their greater density and insulation properties. Compression of the wool can potentially affect its ability to resist fire, so ensuring the encasement does not excessively compress the wool layers is important.
When deciding on the height of the mattress encasement, you should select one that comfortably fits the entire mattress, including the wool batting layers, without compressing them too much. If the encasement is too tight, it might compress the wool layers, which could impact both comfort and fire resistance.
When wool is not compressed, it tends to have more air pockets and retains its natural loftiness. This loftiness can enhance its ability to trap air and moisture, which are important factors in its flame retardant properties.
Non-compressed wool may provide better insulation against heat and slower combustion.
When wool is compressed, these air pockets are reduced or eliminated, which can affect its insulating ability. Compression may also reduce the amount of air and moisture that wool can trap, potentially diminishing its flame retardant properties compared to non-compressed wool.
Most would think that compressed wool might be a better fire retardant than non compressed wool, since fire needs oxygen to sustain itself. But with the reduction of the air pockets comes the reduction of being able to trap moisture. Wool also contains protein that are more difficult to ignite and tend to char rather than melt when exposed to flames.
Since wool has a high moisture content, it has the ability to absorb the heat energy, and intern reduces the temperature, thus slowing down the spread of the flames.
So, even though compression will reduce air pockets, and effect the ability to maintain and absorb moisture, wool’s over all ability and efficacy when wool is compressed alters wool’s natural properties which in turn makes compressed wool less effective than non compressed wool as it relates to fire reduction.
In essence, both compressed and non compressed wool have fire resisting abilities, but wool’s natural properties in its non compressed state is more effective in flame deterrence.
I am not very familiar with the regulations for flame retardant qualities and regulatory compliance. It stands to reason that the top layer of a mattress is the most crucial in its ability to be a flame retardant.
Additionally, since the top layer of a mattress is crucial for flame retardant due to its proximity to the sleeper, regulatory requirements may dictate that multiple layers, including those deeper within the mattress, must also incorporate similar flame-resistant materials such as wool or other approved substances.
Perhaps one of our Trusted Member latex manufactures such as @Arizona_Premium or @Sleep_EZ may be able to shed light on the regulatory requirements as it pertains to multi-layer mattress construction. There may be federal and state regulations that dictate these requirements. In general, when a State’s requirements are more strict, those requirements prevail, unless in the case of anti-trust or restriction of trade issues are involved.
Hope this helps,
Maverick
