Perlite is not a trade name but a generic term for naturally occurring siliceous volcanic rock. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume.

This expansion process is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600 F (870 C) the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles in the softened glassy particles. It is these tiny glass-sealed bubbles which account for the amazing lightweight and other exceptional physical properties of expanded perlite.

The expansion process also creates one of perlite's most distinguishing characteristics: its white color. While the crude perlite rock may range from transparent to light gray to glossy black, the color of expanded perlite ranges from snowy white to grayish white.

Expanded perlite can be manufactured to weigh from 2 lbs/ft3 (32 kg/m3) to 15 lb/ft3 (240 kg/m3) making it adaptable for numerous uses, including filtration, horticultural applications, insulation, inert carriers and many filler applications.

A unique use for perlite is in the manufacture of fire resistant, lightweight, rot proof, simulated stone, masonry, and wood products for a multitude of exterior and interior applications.

Please note: The Schundler Company does not manufacture any simulated stones, bricks, or wall products. We have included this information since perlite and vermiculite often are used in making these lightweight products

Lightweight perlite simulated brick is fire resistant and rot proof, and easy to install.

Lightweight Perlite Molded Products

Perlite simulated stone may be molded to give the appearance of brick, stone, or even wood products. A special advantage of perlite simulated stone is its lightweight. Traditional stone and masonry products are heavy and require more expensive structural support. With simulated stone products, traditional framing and supporting materials are usually satisfactory and installation costs can be reduced. A further advantage of lightweight perlite simulated stone or wood products is reduced shipping costs and ease of handling. In addition, perlite provides an insulating advantage and is rot, termite, and fire resistant. Simulated stone and wood products are excellent for hiding irregular wall surface and may be used in new construction, remodeling, and in exterior and interior applications, depending upon the binder used.

Mix Compounds

Perlite concrete and plaster aggregates conforming to ASTM specifications are commonly used in the manufacture of simulated stone or wood. Binders and other components of perlite simulated stone usually include Type I or Type III portland cement, gypsum, lime, clay, and castable or other resins. Other additions may include sand, shale, coloring agents, silicates, alkaline resistant fiberglass shorts and polypropylene or wood fibers.

Mix Designs

Mix designs for perlite simulated stone products range from 1:4 (binder to perlite) to 1:10 by volume. Mixing is accomplished with ribbon, plaster, or other mixers having low shear action. Paddle type and size should be chosen for the lowest shear rate.

Stone Product Manufacture

Simulated stone products may be formed by pouring or pressing the molding material into relief molds, by extruding or vibrating into wood or steel molds or forms, and my die cutting. Surface finish and configuration of the stone is determined by the mold being used.

Applications for Perlite Simulated Stone

Among the applications for lightweight perlite simulated stone are wood shakes, exterior siding, fireplace logs, and masonry block, brick, and stone for exterior and interior applications.

Perlite also may be used in the manufacture of adhesives, glues, and mortars used to affix simulated stone to a variety of exterior faces. An advantage of perlite in these applications is its function as a filler replacing more costly resins or heavier fillers.

Lightweight perlite simulated brick in a typical home installation.

If you need any more information or think we can help in any way, please call us or contact us at:

Back to Industrial Products Main Page