400 West System Filler Powders
WEST SYSTEM Epoxy fillers are used to thicken the basic epoxy resin/hardener mixture for specific applications. Each epoxy filler possesses a unique set of physical characteristics, but they can generally be categorized as either Adhesive (high-density) for bonding applications or Fairing (low-density) for sanding and fairing applications. Adding these filling agents to blended epoxy resin and hardener allows you to control the consistency of the epoxy, bridge gaps in joints, create either strong or sandable fillets with epoxy, or alter the cured density of epoxy making it easier to sand smooth.
As a rule, use WEST SYSTEM higher-density epoxy fillers when bonding higher-density materials such as hardwoods and metals. Any of the adhesive fillers are suitable for most bonding situations. Your choice of a filler for general use may be based on the handling characteristics you prefer. Fillers may also be blended together to create mixtures with intermediate characteristics.
Adhesive Fillers vs. Fairing Fillers
WEST SYSTEM fillers are used to thicken the basic epoxy resin/hardener mixture for specific applications. Each filler possesses a unique set of physical characteristics, but they can be generally categorized as either Adhesive (high-density) or Fairing (low-density). Adhesive filler mixed with epoxy cures to a strong, hard-to-sand plastic useful in structural epoxy applications like bonding, filleting and hardware bonding. Fairing filler mixed with epoxy cures to light, easily sandable material that is generally used for cosmetic or surface applications like shaping, filling or fairing.
Epoxy Fillers and Epoxy Strength
While certain fillers will increase the density of epoxy, this does not correlate to higher physical properties or increased adhesion strength. Epoxy is strongest without filler added to it, but adhesive fillers are excellent for increasing the viscosity of the epoxy mixture, bridging gaps, preventing the epoxy from soaking too far into the wood, and preventing glue-starved joints. Fairing fillers turn the epoxy into an easily sanded fairing compound.
413 (formally 403) Microfibre
West System 413 (formally 403) Microfibre is a HIGH DENSITY FILLER of fine fibre blends used as a thickening additive for either epoxy or polyester resin to create a multi-purpose adhesive.
Epoxy thickened with 413 microfibres has especially good gap-filling and adhesive qualities while retaining excellent wetting/penetrating capability. Its color is a OFF WHITE. It can be used in a variety of applications and industries being especially good for bonding wood.
404 High-Density filler is a thickening additive developed for maximum physical properties in hardware bonding where high-cyclic loads are anticipated. It can also be used for filleting and gap filling where maximum strength is necessary. Off-white colour.
406 Colloidal Silica
406 Colloidal Silica is a thickening agent for epoxies, polyesters, and urethanes. This Fumed Colloidal Silica can be used to thicken resins to the user desire by adding varying amounts. Commonly known as Cabosil or Aerosil.
Colloidal Silica is ideal for making adhesives and putties for gluing wood, fiberglass, stone, concrete, etc. Cures OFF WHITE but can make cured resins much more difficult to sand.
409 Microsphere Blend (Q-Cell)
409 Microsphere Blend is a pure silicate microsphere. They are a hollow glass bubble based, LOW DENSITY FILLER designed for filling and fairing. Its color is a OFF WHITE. It is popular in the marine industry but can be used in a variety of applications and industries due to its excellent sanding qualities.
410 Microlight Filler
410 Microlight Filler is the ideal low-density filler for creating a light, easily-worked fairing compound especially suited for fairing large areas. Microlight mixes with greater ease than 407 Low-Density filler or microballoons and is approximately 30% easier to sand. It feathers to a fine edge and is also more economical for large fairing jobs. Not recommended under dark paint or other surfaces subject to high temperatures. Cures to a tan color.
411 Microsphere Filleting Blend
411 Microsphere Filleting Blend is a mixture of silicate microspheres and colloidal silica used as a general purpose LOW DENSITY FILLER. It mixes easily with either epoxy or polyester resins to create a thickening agent allowing the user to create fillets that are smooth and require little sanding. Its color is a OFF WHITE. It can be used in a variety of applications and industries and has excellent sanding qualities.
417 (formally 407) Microballoons
417 Microballoons are a LOW DENSITY FILLER used to make fairing putties that are easy to sand or carve. 417 Microballoons are reasonably strong on a strength-to-weight basis. It cures to a DARK RED/BROWN COLOUR. It is popular in the marine industry but can be used in a variety of applications and industries due to its excellent sanding qualities.