From the 1920s to the 1950s, magnesite incorporated elegance and serviceability as a low-cost pourable flooring material, utilized everywhere from Depression-era art deco homes to mass-produced apartment projects to the decking of World War Two battleships. The iconic American architect Frank Lloyd Wright made extensive use of magnesite in residential designs and it was the standout flooring for many houses built with a Spanish or Mediterranean theme.
In the city of Los Angeles alone, it’s estimated that at least 4 million square feet of vintage magnesite flooring still survives in existing houses and apartment buildings, a lot of it now sadly covered up by carpet or vinyl tile.
Technically called diato magnesium oxychlorite (and also sometimes referred to as “diato flooring”) magnesite is a blend of magnesium chloride and a finely ground organic filler such as sawdust, mixed with water. Colorant is added to produce a wide range of hues. The mixture pours like wet cement and is then spread out by trowels, typically on top of a wood floor covered with wire mesh or directly onto a concrete slab. Most magnesite flooring of the past was anywhere from 1/2-inch to 3/4-inch thick.
Think of magnesite as a sort of plaster for the floor. Because it’s a wet mix that is workable after pouring, it takes on some of the aesthetic potential of plaster. Depending on the coloration added, magnesite can mimic many other flooring materials. While still wet, magnesite can be decoratively stamped, or scored to give the appearance of individual tiles.
Buyers of classic homes today are occasionally surprised to be informed by a contractor that a floor initially assumed to be ceramic tile or even brick is actually poured magnesite from the 1930s. Indeed, when highly stylized magnesite flooring was installed in expensive residences of that era, the workers who did the job were usually considered skilled artisans.
The Virtues of Magnesite
Why was magnesite the flooring fad of the early 20th century? Several factors combined to make this mixture so popular at the time and still hold substantial appeal even today.
Because wet magnesite is a pourable, spreadable material, it can be adapted to flooring in a wide variety of places. Virtually anywhere this mixture can be poured into place and smoothed, magnesite cures into hard flooring. Imprints and designs of all sorts can be applied and the wet material can be molded into curves and other shapes impossible to achieve with linoleum, ceramic, or stone flooring.
Areas of the house that were problematic for installing conventional floor tiles can be readily coated with a half-inch deep layer of wet magnesite applied directly to the wood subfloor, then dried to a hard, impermeable surface. Because dried magnesite is comparatively lightweight, it can be installed in areas not structurally appropriate for heavy stone flooring like slate or marble.
After pouring, wet magnesite can also be conformed into a slight slope to shed water. The material has thus often been utilized in outdoor applications such as patio floors.
Magnesite is actually classified as a variety of cement. That fact alone conveys something about the durability of the material. However, magnesite differs from cement in that it contains wood pulp or sawdust that also adds resiliency. Cement is a strong but brittle material.
Magnesite, on the other hand, has a certain amount of “give” that makes it more durable under normal household wear and tear. Strike a magnesite floor with a heavy object like a hammer and it would probably dent, but not crack or break open like more brittle flooring such as ceramic tile or stone. A magnesite floor should last at least 30 years and many carefully maintained floors from the golden age of magnesite 60 years ago are still intact and beautiful.
Magnesite is impervious to oil or grease. Because it is a poured material, a magnesite floor is totally seamless so there are no issues with grout staining or discoloration that are typical maintenance concerns with other types of tile. Nor is water penetration between individual tiles a problem. Back in the day, magnesite was typically maintained with regular applications of tung oil or basic old-school floor wax.
Today, magnesite is usually sealed every 18 months with modern acrylic sealants similar to those utilized for concrete.
Magnesite is non-flammable and fireproof. That’s another big reason for its utilization in home and apartment building construction of the early 20th century. Prior to magnesite, flooring in many homes and rental units was often simply finished wood or cheap linoleum, in those days, a highly flammable material. The fire hazard was substantial and fires in multi-unit buildings with many fatalities were common.
Composed of low-cost ingredients, magnesite was a price-competitive and safer alternative to bare wood or flammable linoleum. It could be quickly poured into place and after drying would not ignite when exposed to common fire sources such as dropped cigarettes or matches. The military still utilizes magnesite flooring to this day in environments where high explosives are present but a steel floor would be dangerous due to the potential for sparks.
Magnesite in the 21st Century
Magnesite is enjoying a sort of renaissance today as it is increasingly utilized in homes and commercial settings where the design scheme calls for a classic ambience that harks back to the early 20th century. In existing homes from that era where magnesite flooring is still in place, but perhaps long-since covered by other flooring, homeowners are increasingly opting to reveal the original floor material and restore it to like-new condition.
New installations of magnesite are also increasingly doable, with two caveats. First, pouring a magnesite floor is a specialty not offered by most flooring contractors. It may be considered a skill that is not widespread in the industry, though it is becoming more available as demand continues to resurge. Depending on your location, a person with the expertise required to do the job may still be hard to find.
However, outfits that repair existing magnesite floors may also do installation of new floors, as well, or can refer you to someone qualified to do so. Second, because it is a specialized skill, magnesite is typically more expensive than many (but certainly not all) other flooring materials in common use today. While the basic ingredients of magnesite and the tools utilized are not costly, the expertise to achieve the desired result usually comes at a higher price.