Fiberfrax Ceramic Boards

Armil CFS Ceramic Fiber Boards

When looking for an insulating backup to brick, castable, or dense refractories, Fiberfrax Duraboard is a great option to consider. Fiberfrax Duraboard is a high temperature, ceramic fiber board manufactured using alumina-silica fibers and binders. These products have a low thermal conductivity, high temperature constancy, uniform density, and outstanding resistance to chemical attacks or thermal shock. 

These features allow Fiberfrax Duraboard to perform exceptionally for applications that involve erosive forces, mechanical stress, and vibration. The board gets its strength from small quantities of organic and inorganic fibers added during the manufacturing process. The binding agents are then burned out during the initial heat up by the end user at temperatures between 450°F and 600°F. 

Ceramic Fiber Boards for Industrial Application

Another major benefit of these boards is the ease of handling and installation. Fiberfrax Duraboards are lightweight and easy to machine or cut, which assists in faster turnaround times for an assortment of industrial insulation applications. Once the boards are installed, reduced energy costs, cycling times and protection for refractory surfaces from thermal shock are added benefits. 

Armil CFS offers Fiberfrax Duraboard products that can be used for a variety of applications that include the following: 

  • Full thickness refractory lining
  • Insulating backup to brick, castable, or dense refractories
  • Flue & chimney linings in furnaces & kilns
  • Heat shields for personal protection
  • Wood-burning stove backup insulation
  • Rigid high temperature gaskets & seals
  • Trough linings & covers for conveying molten metals
  • Use in industrial heat processing equipment
  • Pouring forms for castable
  • High-Temperature baffles & muffles

For temperature applications up to 2300°F, Fiberfrax Duraboard LD and HD are the best options. Duraboard LD has a smooth finished surface and is ideally used for application as a sandwich or core material. It is also applied when performance and uniformity are important. 

Duraboard HD is very similar to LD, however it provides enhanced compressive strength and a higher modulus of rupture. Clay additives during the manufacturing process provide HD with more strength and density. 

For temperature applications up to 2600°F, Fiberfrax Duraboard 2600 is the best ceramic fiber board. Duraboard 2600 board is fabricated with a blend of patented polycrystalline mulite fibers to provide stability at higher temperatures.   

For temperature applications up to 3000°F, Fiberfrax Duraboard 3000 is the number 1 choice. Duraboard 3000 is the highest rated temperature board manufactured by Unifrax and delivers shrinkage resistance and dimensional stability at elevated temperatures. 

For more information about Ceramic Fiber Boards, visit or call (708) 339-6810



Fiberfrax High Temperature Ceramic Fiber Blankets

When searching different websites or stores for the right Ceramic Fiber Blankets, there are many different options to choose from. Most people are looking for a blanket that has the following features:

  • Excellent hot strength
  • Thermal shock resistance
  • Handling Strength
  • Corrosion resistance
  • Low heat storage
  • Low thermal conductivity
  • Outstanding fire protection
  • Light weight
  • High Heat Reflectance
  • Thermal Stability

Most blankets can offer some of these characteristics, but only the Fiberfrax Durablanket can deliver them all.

The Fiberfrax Durablanket is a thermally efficient ceramic fiber insulating material that combines constancy at high

temperatures with total resistance to thermal shock. Durablanket products are high strength, needled blankets spun

from Fiberfrax ceramic fibers. The blanket acquires it’s handling strength from extra-long spun fibers that are cross

locked through a one of a kind forming process. Fiberfrax Durablanket products are unaffected by most chemicals,

resulting in exceptional chemical stability.

Armil CFS offers a variety Fiberfrax Durablanket products that can serve the following applications:

  • Furnace, kiln, reformer, and boiler linings
  • Furnace repairs
  • Investment casting mold wrappings
  • High temperature kiln and furnace insulation
  • Furnace door linings and seals
  • Reusable insulation for steam and gas turbines
  • Flexible high-temperature pipe insulation
  • Glass furnace crown insulation
  • High-temperature seals, gaskets, and batten strips
  • Incineration equipment and stack lining.

Armil CFS offers a variety Fiberfrax Durablanket products that include Durablanket S, Durablanket 2600, and

Moist-Pak D.

Fiberfrax Durablanket S is best used for applications up to 2300° and is manufactured in a variety of thicknesses,

widths, and densities. This blanket is lightweight, strong, and offers a wide array of solutions for any insulating

problems. Check out our Fiberfrax Durablankets


Insulfrax S Bio-Soluble High Temperature Insulating Blanket

Insulfrax S Bio-Soluble High-Temperature Insulating Blanket ApplicationsInsulfrax® S fiber chemistry has been combined with Unifrax’s proprietary fiber spinning technology to create a specialty high-temperature blanket with superior thermal and mechanical properties. Insulfrax® S calcium, magnesium, silicate chemistry provides thermal insulation at continuous operating temperatures to 2012°F. Insulfrax® S meets European regulatory requirement (Directive 97/69EC).

Insulfrax® S is classified by Underwriters Laboratories (UL), per UL723 (ASTME-84). Flame Spread Rating=0, Smoke developed rating=0

Insulfrax® S Blanket is a flexible, strong, lightweight, needled blanket produced from Insulfrax® Fiber. Mechanical needling of the spun Insulfrax® fibers eliminates the need for binders in the product’s manufacture and results in a product with high tensile strength. Since Insulfrax® S Blanket is completely inorganic, the product exhibits no smoke generation or outgassing in service. Insulfrax® S Blanket combines low thermal conductivity with excellent resistance to thermal shock. Note that high humidity and wetting with water prior to service has little effect on Insulfrax® S Blanket.

Typical applications:

  • Residential self-cleaning ovens
  • Wood Fired Ovens
  • High-temperature commercial cooking appliances
  • High-temperature gasket material
  • Hearth Products
  • Chimney Insulation
  • Expansion joint seals
  • Aluminum transfer ladle covers
  • Backup insulation for dense refractory linings
  • Backup insulation for refractory ceramic fiber or Isofrax® linings
  • Maintenance blanket
  • Heat shields
  • Stress Relieving Blankets
  • Reusable insulating pads
  • External duct insulation

Soluble Fiber Blankets – Silica Blankets Data Sheet

Purchase Insulfrax® S 


Fiberfrax Applications In Heat-Treating and Metalworking Industries

Since 1976, Armil CFS has been providing Fiberfrax ceramic fiber products to the heat treating and metalworking industries. We offer a full range of Fiberfrax blankets, boards, braids, caulks, cloth, felts, modules, papers, ropes, tapes, and vacuum formed shapes. For more information on these  and other applications, please contact us.


  • Burner blocks
Fiberfrax Vacuum Formed Parts
  • Covers
Fiberfrax Durablanket S, Fibersil Cloth, Refrasil Cloth
  • Curtains
Fiberfrax L144 Cloth, Fibersil cloth, Refrasil Cloth
  • Emission control
Fiberfrax Paper
  • Expansion joints
Fiberfrax Paper, Fiberfrax DuraBoard LD, Fiberfrax Durablanket S
  • Furnace linings
Fiberfrax Durablanket S,  Duraboard LD, Duraboard 2600,  AnchorLoc Modules
  • Gaskets
Fiberfrax Papers, Duraboard LD
  • Heat retention box
Fiberfrax Durablanket S, Duraboard LD
  • Heat shields
Fiberfrax Durablanket S, Fibersil Cloth, Duraboard LD
  • Hot gas filtration
Fiberfrax Durablanket S
  • Hot spot repair
Fiberfrax LDS Moldable, Silplate M
  • Insulation
Fiberfrax Durablanket, Fiberfrax Duraboard, Insulfrax Blanket, Isofrax Blanket
  • Mold linings
Fiberfrax Paper
  • Mold Wrap
Fiberfrax Durablanket, Insulfrax Blanket, MoistPak D,
  • Personnel / equipment protection
Fiberfrax Durablanket, Fiberfrax Duraboard, Fibersil, Refrasil
  • Pouring pads
Fiberfrax Duraboard
  • Refractory backup
Fiberfrax Paper, Fiberfrax Duraboard RG, Fiberrfrax Durablanket S
  • Seals
Fiberfrax Paper, Fiberfrax Twisted Rope, Fiberfrax Round Braid, SquareBraid
  • Stress relieving
Fiberfrax Durablanket S
  • Tubes
Fiberfrax Paper, Fiberfrax Vacuum Formed Shapes
  • Veneers
Fiberfrax Durablanket Blanket, Fiberfrax Bonded Modules
  • Weld splatter shields
Refrasil Cloth, L144 Cloth, Fibersil Cloth

Press Release: Armil CFS Ships Pusher Furnace to European Manufacturer

An Armil CFS Pusher furnace in action

Armil CFS, Inc has shipped a gas fired pusher furnace to a European manufacturer of investment castings for the medical industry. The 2 row pusher furnace will be used for the burnout and pre-heating of investment casting molds.

The furnace has an operating range of 1,650°F to 2,100°F. Residual wax will be consumed within the furnace chamber, eliminating need for an afterburner.  A recuperative combustion system will utilize a series of high velocity burners operating in 3 zones of control. The furnace incorporates an industrial PLC and touchscreen based HMI.


Armil CFS, Inc; located in South Holland, IL; is a manufacturer of custom furnaces for ceramics, fire testing, forging, investment casting, heat treating, incineration, etc… Armil CFS also manufactures Tru-Heat pre- engineered box furnaces for a variety of high temperature applications.


Application Data: Fiberfrax Products for Wood Burning Stoves

Fiberfrax for Wood Burning StovesFiberfrax ceramic fiber products provide a simple and effective way to save energy in wood burning stoves. Manufacturers use a number of these ceramic fiber forms to improve fuel efficiency and safety in there units.

For many producers, Fiberfrax products replaced asbestos that had been used historically, eliminating potential health hazards. For others, Fiberfrax is a substitute for fiberglass products that assures better performance at high temperatures.

Fiberfrax Twisted Ropes, Fiberfrax Round Braid, and Fiberfrax Square Braid can all be used as an air-tight door seal to help control combustion, provide a steady heat flow, and conserve energy. Fiberfrax Rope can also be used for ash pan gaskets.

Fiberfrax Duraboard and Fiberfrax Durablanket S can be attached to the back panel of the unit to serve as a safety device, allowing the stove to be positioned closer to the wall. They can also provide thermal insulation required for stove boards and decoration panels. Fiberfrax Duraboard LD can be used as a back up for hard refractory to reduce heat loss and conserve energy.

FIberfrax panels for wood burning stovesFiberfrax Duraboard LD has also been used as internal baffle board in wood fired stoves. Duraboard LD is easy to cut with hand tools to insure a proper fit. Duraboard LD has also proven successful as an insulating board in wood fired pizza ovens.

Fiberfrax LDS moldable is a high temperature caulking compound that can be applied around piping system to prevent leaks.

Why use Fiberfrax?

  • Contains no asbestos
  • Saves Energy
  • Competitively priced
  • Will not deteriorate
  • Reduces fuel costs
  • Produces better heat flow
  • Easy to cut
  • Upgrades safety
  • Higher temperature limits than fiberglass

Application Data: Refrasil for Welding Protection

Refrasil - Silica Cloth, Silica Curtain, welding cloth, welding blanket, Irish WebRefrasil Protects from welding sparks and spatter
Refrasil is a preferred alternative to cotton/wool, fiberglass and other heat shielding material for protecting personnel, equipment and finishes from sparks and molten metal splash during welding and torch cutting operations. A single layer of Refrasil will often provide the same protection as several layers of other fabrics.

Both Refrasil UC100 and abrasion-resistant AR100 series products have important advantages. They protect at higher temperatures, exhibit minimal dusting and fly-off of fiber particles, and present no known health hazard. A low chloride content makes Refrasil particularly suited for nuclear welding applications.

While Refrasil protects and retains flexibility at 1800°F, with excursions to 3100°F, fiberglass breaks down at temperatures exceeding 1000°F. Also, unlike Refrasil, fiberglass is irritating to the skin of the welder unless treated with finishes, some of which are either flammable, smoke-producing, or generate toxic fumes. Other fabrics afford only minimal protection and lose their heat resistance at comparitevely low temperatures, e.g., at approximately 450°F to 650°F.

Contains weld spatter better than fiberglass
When using fiberglass as a weld blanket, one must allow for more of a drop space than with Refrasil; weld spatter can be contained closer to the work area when using Refrasil. The fact that the same welding application can be handled with less material gives the user a definite cost incentive for using Refrasil instead of fiberglass. Also, when the weld splatter hits fiberglass it will burn through, potentially causing costly damage. Refrasil weld blankets, on the other hand, have sufficient toughness and heat resistance to prevent penetration from hot spatter.

Reuse gives Refrasil AR100 a major cost advantage
Reuse is a major cost advantage favoring Refrasil AR100 series fabric. It has a tough, sacrificial orange colored treatment that improves abrasion resistance, durability, and handling characteristics. It is resistant to minor dragging, scraping, tearing and snagging, as well as offering 50% improved seam strength over standard Refrasil. AR100 is easily fabricated by conventional methods of stitching, sewing and grommeting. Reusability makes Refrasil AR100 particularly cost effective, especially if one has a good recovery system with storage provisions.

Low Thermal Conductivity
Thermal conductivity curves demonstrate the effectiveness if Refrasil as a weld blanket. Refrasil’s thermal conductivity properties are lower than most heat shielding materials. Refrasil resists heat flow more effectively than other heat-resistant fabrics, fiberglass or natural fibers.

Available in rolls or pre-cut
As a utility material for dropcloths or general weldprotection use, Refrasil UC100 and AR100 series are available in rolls and the user merely cuts the required length to suit the application. Standard roll sizes for all Refrasil cloth products are 50 lineal yards, +/- 10%.
Armil CFS also offers Refrasil UC100 in 1 yard or 5 lineal yard lengths. Other custom sizes are available.

Refrasil cloth products are manufactured in the USA!


Application Data: Fiberfrax and Pottery

With Fiberfrax Ceramic Fiber being twice as good an insulator as insulating firebrick at operating temperatures to 2300°F and 2600°F, being light weight and completely resistant to thermal shock, it isn’t any wonder that inventive applications by creative potters and hobbyists keep occurring. Assisting the imagination of the potter is the wide variety of more than forty different Fiberfrax forms, such as bulk fibers, blankets and felts, cements, castables, moldables, blocks and boards, textiles, and even paper.

One of the most beneficial creations has been the idea of lining a 55 gallon drum with either Fiberfrax H Felt1(2600°F) or Lo-Con Felt2(2300°F), resulting in a 22-inch diameter by 33-high portable kiln. This kiln is beneficial in many ways since it is very inexpensive to build, and can be built in about 2 hours. Because Fiberfrax weighs one fifth that of IFB, the kiln can be lifted from the base either manually or by a cable and pulley system. This is much safer than the conventional IFB kiln since the worry of burning ones arm on the hot firebrick walls is eliminated. Another important advantage has an ecological aspect. Fiberfrax reflects the heat into the furnace; therefore, a faster heat-up and cool-down cycle can be obtained requiring less fuel consumption. One potter stated a reduction of fuel costs by 15 to 25%.

For larger sized kilns, the Fiberfrax Fiberwall system may be used. This concept consists of mineral wool, Lo-Con Felt2, and and Fiberfrax H Felt1 impaled over studs which are welded to the steel shell. The Fiberwall materials can be secured by an inconel clip or ceramic clip. This concept is slightly more sophisticated and expensive than the 55-gallon drum but, nevertheless, is justified by reduced fuel consumption, ease of installation, and increase in productivity due to less firing time required.

A more familiar application to many potters is the use of Fiberfrax Bulk Fiber as an expansion joint packer and crack stuffer in conventional IFB kilns.

Fiberfrax Rope and other textile forms have been used as seals and protective barriers.

These are a few ways Fiberfrax ceramic fiber paper products can be used, but there may be many ideas yet to be discovered. Use your imagination to have Fiberfrax save you time and money.

1. Fiberfrax H felt has been replaced by Fiberfrax Durablanket 2600.
2. Fiberfrax Lo-Con felt has been replaced by Fiberfrax Durablanket S.

Originally printed by Carborundum
Excerpted from Form C547-11/77


Insulating Firebrick

Insulating Firebrick are a low density firebrick used for insulation purposes in kilns, furnaces, incinerators, boilers, and other high temperature process equipment.

Armil CFS stocks a wide variety of insulating brick manufactured in the USA by BNZ Materials.

BNZ Materials manufactures high quality firebrick in their Zeienople, PA plant that originally manufactured JM insulating firebrick. JM insulating firebrick are now called BNZ insulating firebrick. Most other companies offering JM insulating brick are using the JM trade name only. They are not manufacturing using the JM process. Most of this brick is manufactured overseas.

Following Grades are in stock in 9” x 4-1/2” x 2-1/2” straights. Please call for other available sizes

  • BNZ 23HS
  • BNZ 26
  • BNZ 28
  • BNZ 3000
  • BNZ 32

Specialty Grades in stock

  • BNZ C22Z
  • BNZ 26-60
  • PA 23 Coarse
  • PA 26 Coarse

Bricks available by special order

  • BNZ 2000
  • PA 2000
  • BNZ 2500
  • BNZ 26 HS

50th Year Anniversary of ArmilCFS Heat Treating Solutions

Armil CFS, Inc. proudly celebrates 50 years of serving high temperature industrial process markets across North America.  We continue the legacy established by Richard O. Marek in 1968 by delivering engineered heat treatment solutions – providing state of the art refractory equipment such as industrial furnaces and refractory supplies manufactured with sound material choices and exceptional workmanship.  Many thanks to all our customers, employees and vendors we’ve worked with for the past half-century!

Please view our images below…

The Armil CFS team pose for our 50-Year photo. Left hand-held
photo is of Dick Marek, founder of Armil CFS; center hand-held
photo is of Walter Parduhn, past president and the owner of
Armil. 50 years of successful heat treating solutions for industrial needs!
One of our beautiful and rugged Car Bottom furnaces
An Armil CFS Pusher furnace in action
A Roller Hearth Burnout furnace installed efficiently at a client location
A Burnout / Preheat Box-Style furnace glows red-hot with power

Read the INCAST article on our 50th anniversary here.