The AF 820 System is a flakeglass filled bisphenol polyester resin that is applied to a total thickness of approximately 20 mils. The lining consists of approximately 100 individual layers of overlapping inert glass flakes. Each layer of flakes is bonded with an extremely chemical resistant resin which provides an excellent vapor and chemical barrier that reduces permeation to the lined substrate. Armor Flake 820 bonds to steel, wood, and concrete. Used to line surfaces that are exposed to strong chemical splash and fumes, Armor Flake 820 demonstrates very good chemical resistance, toughness, and resistance to abrasion. A few uses for Armor Flake 820 lining are:

  • storage vessels and tanks
  • paper mill units
  • chemical and waste treatment units
  • sulfur dioxide stacks and scrubbers
  • ship and barge hulls
  • petroleum or sour crude units
  • steps and handrails
  • water or brine storage tanks

The three coat AF 820 system is easily applied by spray. The three components of the system are:

  • AF 820-1 Primer – bisphenol polyester resin
  • AF 820-2 Spray Grade Lining – flakeglass bisphenol
  • AF 820-3 Sealing Coat – bisphenol polyester with wax added

Chemical Resistance

Armor Flake 820 is resistant to acids, chlorine, muriatic acid, petroleum solvents, brine, bleaches, salt solutions, steam, sulfuric acid and many caustics. Contact the Wil-Cor, Inc. Technical Department for chemical resistance in specific service conditions.


  • High resistance to acids
  • Easy application
  • Bonds to steel, wood or concrete

Physical properties

Color Off White
Water Vapor Transmission 0.0008 Perm Inch
Solids Content 100%
Maximum Service Temperature
Continuous exposure 175 °F
Intermittent exposure 350 °F
Flash Point 85 °F
Cure Time @ 75 °F 48 hrs
Bond to Steel 2,000 psi
Abrasion Resistance, Tabor CS-17 wheel 72-76
Barcol Hardness (ASTM D-2583) 36-40
Coefficient of Expansion, in./in./°F 12-16 x 10-6
Thermal Conductivity, BTU/sq. ft./hr/°F/in 1.30

Installation Recommendation

Wil-Cor, Inc. recommends supervision by Wil-Cor or installation by experienced fiberglass installers. Preparation, mixing and application information is provided for installers with adequate installation experience.


All components of the Armor Flake 820 Lining System are catalyzed with Armor Plate 60, methyl ethyl ketone peroxide. The mixing ratio is 1.0-2.0 oz. of catalyst for each gallon of AF 820-1, AF 820-2, or AF 820-3. NEVER use more than 2.0 oz. of catalyst per gallon of Armor Flake 820 component.

Catalyzed Armor Flake 820 components have a short pot life. Mix only enough material to use during a short period. Inhibitor may be added at a rate of 0.25-0.5 oz. per gallon of resin.

Begin the mixing process with 1 quart of AF 820-1, AF 820-2, or AF 820-3, and the proper proportion of catalyst. Measure the quantities of catalyst and component carefully, because only a small amount of catalyst is necessary for each quart of component.

After the catalyst and component are thoroughly mixed, remove the material from the mixing pot and quickly spread over the surface. Catalyzed material will not set up as quickly if it is not concentrated in the pot. Immediately follow the initial spreading process with a thorough application procedure.

If the applied material does not set up within 3 to 4 hours, the amount of catalyst in the mixture may be increased. DO NOT add more than 2.0 oz. of catalyst per gallon of component.

Surface Preparation

For Concrete:

  • 1All surfaces must be clean. Remove all dirt, oil, grease and contamination by sandblasting or acid wash.
  • 2All surfaces must be sound. Remove laitance, powdered concrete, or weak concrete by sandblasting.

For Steel:

  • 1All surfaces must be clean. Remove any oils, greases, or chemicals and sandblast to white metal.
  • 2Prime the surface immediately with Armor Flake 820-1 Primer to prevent rusting. The primer is not necessary if the Armor Flake 820-2 lining is to be applied within 8 hours of sandblasting.

For concrete, carbon steel, or wood:

  • 1The surface to which Armor Flake 820 is applied should be smooth, without cracks, pits or sharp burrs. Rough areas may be smoothed or filled with Armor Plate 805, a catalyzed putty material, or they may be topped with a laminate consisting of a 1.5 oz. mat or cloth tape saturated with AF 820-1 Primer.
  • 2All baffles, nozzles and flanges should have a laminate applied before the AF 820-1 Primer is applied.


Armor Flake 820-2 Lining:

  • 1Armor Flake 820-2 is applied by spray, roller, or brush to a nominal thickness of 12 – 15 mil.
  • 2AF 820-2 may be applied after the AF 820-1 Primer and any patched areas are hard to the touch.

Armor Flake 820-3 Sealing Coat:

  • 1Armor Flake 820-3 is applied by brush or roller to a nominal thickness of 5 – 8 mils.
  • 2AF 820-3 may be applied after the AF 820-2 Lining is hard to the touch.
  • 3To obtain a non-skid surface, sprinkle clean, sharp sand on the AF 820-3, coat while it is still soft. Completely cover the surface with the sand, and after the resin has set, sweep off any loose, excess sand.
  • 4Spark test the applied lining with a 2,500 volt spark tester.
  • 5Allow approximately 12 hours of cure time before the lining is placed in light service. A full cure will require 48 hours.
  • 6DO NOT add solvent to thin. Thin with AF 820-1.


The Armor Flake 820 Lining System is not recommended for large concrete areas.


Armor Flake 820 components are available in stock sizes of 1-quart, 1-gallon and 5-gallon, with Armor Plate 60 catalyst in a separate container.

Coverage and Estimating

The theoretical coverage of the Armor Flake 820 components

AF 820-1 Primer 100-150 sq. ft./gal (Depends on surface texture)
AF 820-2 Lining 75 sq. ft./gal (Provides 15 mil thickness)
AF 820-3 Sealing Coat 150-175 sq. ft./gal (Provides 5 mil thickness)

Shelf Life

Armor Flake 781 components have a shelf life of approximately 3 months when stored under dry conditions, around 75 °F.

Freight Classification

Resin Solution, Flammable Liquid


For Industrial Use Only! – Flammable Liquid

Resin Component

  • Causes eye or skin irritation. Always wear suitable clothing to minimize skin Contact.
  • Vapor caused headache, dizziness, nausea and unconsciousness. Area must be ventilated. If inhaled, remove victim to fresh air. Give artificial respiration if not breathing.
  • For eye Contact, flush with water immediately.
  • For skin Contact, wash with soap and water immediately. Remove contaminated clothing.
  • If swallowed, give large amounts of milk or water to drink and seek immediate medical attention.
  • Flammable. Keep away from all sparks, flames or heat. Extinguish fires with foam, dry chemical, carbon dioxide or water spray.

Hardener – AP 60 (Methyl Ethyl Ketone Peroxide)

  • Store in a cool place away from all sources of heat.
  • NEVER store near cobalt naphthenate or other promotors, accelerators or strong reducing agents.
  • Strong irritant. Ingestion can be fatal. If swallowed, induce vomiting and call physician.
  • For eye contact, flush with water for 30 minutes and call physician immediately.
  • For skin contact, wash with soap and water immediately. Remove contaminated clothing.

Before use, review Material Safety Data Sheet for further information. Read and follow the hazard information and first aid directions on each product label before using.