VFI®-4385 82 D Form Coating Epoxy

A form coating is used to protect and seal expensive precast forms and surfaces, preventing abrasive casting materials from damaging them. It also enables castings to release from the surface easier for a smooth finish.

VFI’s form coating is an epoxy. Epoxy is hard, durable, and can be used on various surfaces, including wood, metal, and foam.

Yes, VFI does offer a few different alternatives to epoxy. The VFI-2538 70 D EPS Form Hard Coat is an alternative coating for EPS surfaces that must be protected from abrasive casting materials. Alternatively, VFI offers a handful of TDI molding rubbers ranging from 25 A to 95 A in hardness for making cast stone molds, manufactured stone molds, formliners, and stamps.

Epoxies and polyurethanes are thermosetting polymers that can be formulated for various uses. When formulated for form coating, these materials differ slightly.

A form coating epoxy can only be applied by brush or roller, whereas a urethane form hard coat can be applied by low pressure, high pressure, or Qwik Spray equipment.

The epoxy is harder than the urethane and has greater tensile strength. It is moisture-insensitive, meaning it can be used in damp and humid environments. Urethanes have a shorter pot life but also have a shorter cure time than epoxies for quicker turnarounds on projects.

Yes, it can be used on wood as long as it is clean, relatively dry, and sanded. Properly preparing the surface will ensure the adhesion of the coating.

Yes, it can be used on metal surfaces like steel as long as it is clean and sanded or sandblasted to SP6. Any rust, mill scale, dirt, or other contaminants can hinder adhesion, so the surface must be properly prepared.

A form coating epoxy can also be applied to EPS foam. Before you coat the surface, the foam must be aged for at least 30 days. VFI recommends using foam between 1 and 3 PCF, but 2 PCF foam will offer the best cost-to-quality ratio. If the foam is clean and dry, the coating can be applied directly to it.

The coating is a bold blue color, making it easier to track when applying in layers.

While the epoxy can be applied using a non-shedding chip brush, VFI typically recommends using a non-shedding nap roller. It makes it easier to keep the surface uniform without brush strokes or other surface defects. Mil gauges are also used to maintain an even thickness.

The form coating has the best performance when applied at temperatures between 60-80°F. If the temperature is above the recommended maximum, the working time of the coating will decrease. The material must be stored in sealed containers between 60-90°F when not in use.

Premix the B side material. Measure the correct amounts of the A and B sides before combining them. VFI-4385 has a mix ratio of 2A:1B by volume or 100A:44B by weight. Mix up only what you need to prevent excess material. After mixing in one container, transfer to a new, clean container and mix again.

When ready to apply, do not leave the material in the mixing container. It will over-generate heat, which will cause it to thicken and cure faster. Leaving it in the container too long can cause an extreme buildup of heat and may cause the material to smoke.

The coating should be applied evenly at a rate of 20 mils per layer. Back rolling can help achieve a uniform thickness. The total thickness should not reach 250 mils or a quarter inch.

Yes, the form coating epoxy is hard enough for sanding to provide a uniform casting surface. However, an approved respirator should be used because airborne particles can be toxic if ingested.

Yes, since we recommend applying at 20 mils, you must apply the coating in multiple layers to build thickness. The surface must be sanded between each layer to ensure adhesion of the next coat.

Yes, but the number of layers depend on the strength of the magnet. We recommend no more than three layers to ensure good magnetic strength.

The form coating epoxy is meant to be reapplied after it has worn down. All you need to do is sand down the existing coating to remove casting residue and apply a new coat.

Yes, the form coating can be repaired. Sand down the areas that have become worn or damaged and apply a new coat of material.

Yes, we recommend using a concrete or stone release agent like ChemTrend’s CR-19597, which is ready to use or can be diluted.

A release agent should be applied after each cast to maintain the integrity of the form coating. This will prevent the casting material from bonding to the surface.

The form can be placed into service after curing for 16 hours at room temperature. It will take 4-5 days at room temperature to obtain full strength and formulated properties.

VFI aims to be competitive with our prices, but it will ultimately depend on the availability of raw materials and the raw materials used in the formula. Also, because we manufacture our own products, it keeps prices down and gives us full control of the manufacturing process.