Filler Selection Guide

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.

Uses & Characteristics
with epoxy resin/hardener mixture
Adhesive Fillers

⇐  Highest Density/Highest Strength

Fairing Fillers

Lowest Density/Easiest Sanding ⇒

404-15 High-Density Epoxy Filler for bonding
404

High-Density

406-2 Colloidal Silica Epoxy Filler for bonding
406

Colloidal Silica

403-9 Microfibers Epoxy Filler for bonding, 6 oz
403

Microfibers

405 Filleting Blend Epoxy Filler for bonding
405

Filleting Blend

407-5 Low-Density Epoxy Filler for fairing
407

Low-Density

410-2 Microlight Epoxy Filler for fairing
410

Microlight™

Bonding Hardware with Epoxy
—Increase load capacity
—Maximum strength
404 High-Density Filler is best for bonding hardware with epoxy­ 406 Colloidal Silica is good for hardware bonding with epoxy 403 Microfibers are good for bonding hardware with epoxy
General Bonding with Epoxy
—Structural gap filler
—Strong, gap-filling
404 High Density filler is good for hardware bonding with epoxy 406 Colloida Silica would be a better choice for general bonding with epoxy
Bonding with Fillets with Epoxy
—Increase joint bonding area
—Structural brace between parts
—Smooth, strong
406 Colloida Silica would be a better choice for filleting with epoxy 406 Colloidal Silica is best for creating epoxy fillets 405 Filleting Blend is good for making fillets with epoxy 407 Low-Density filler is good for making sandable fillets with epoxy
Laminating with Epoxy
—Bond layers
—Gap-filling, strong
406 Colloidal Silica is good for laminating with epoxy 403 High-Density filler is best for laminating with epoxy
Fairing with Epoxy
—Fills voids
—Easily sanded
—Gap filling
407 Low-Density Filler is good for fairing with epoxy 410 Microlight Filler is best for fairing with epoxy

 

Adhesive Epoxy Fillers

Adhesive fillers are suitable for most epoxy bonding situations especially with high-density materials like hardwoods and metals. Adhesive filler mixtures cure to a strong, hard-to-sand cured epoxy plastic useful in structural applications like general bonding, filleting and hardware bonding.

Fairing filler epoxy mixtures cure to light, easily sandable material that is generally used for cosmetic or surface applications like shaping, filling or fairing. Seal all faired surfaces with epoxy before painting.

Epoxy Additives

Additives are used to give epoxy additional physical properties when used as a coating. Although additives are blended with mixed epoxy in the same two-step process as fillers, they are not designed to thicken the epoxy. See Additives & Pigments. Follow the mixing instructions on the individual additive containers when blending these products into your epoxy resin/hardener mixture.

General use filler selection may be based on the epoxy handling characteristics you prefer. Fillers may also be blended to create epoxy mixtures with intermediate characteristics.

Filler Buying Guide

Quantity of mixed epoxy required for consistency:

 

WEST SYSTEM

Epoxy Filler

Package
Size
Package
Weight
Epoxy filled to
Catsup
Consistency
epoxy filled to catsup consistency
Epoxy filled to
Mayonnaise
Consistency
epoxy filled to mayonnaise consistency
Epoxy filled to
Peanut Butter
Consistency
epoxy filled to peanut butter consistency

403-9 Microfibers Epoxy Filler for bonding, 6 oz
403 Microfibers
403-9
403-28
403-B
6.0 oz
20.0 oz
20.0 lb
3.8 qt
3.2 gal
48.0 gal
2.5 qt
2.0 gal
32.0 gal
1.0 qt
.9 gal
15.3 gal

404-15 High-Density Epoxy Filler for bonding
404 High-Density
404-15
404-45
404-B
15.2 oz
43.0 oz
30.0 lb
1.2 qt
3.6 qt
9.4 gal
.9 qt
2.8 qt
7.4 gal
.7 qt
2.0 qt
5.3 gal

405 Filleting Blend Epoxy Filler for bonding
405 Filleting Blend
405 11.0 oz .8 qt .6 qt .5 qt

406-2 Colloidal Silica Epoxy Filler for bonding
406 Colloidal Silica
406-2
406-7
406-B
1.7 oz
5.5 oz
10.0 lb
1.3 qt
1.1 gal
27.0 gal
.9 qt
3.0 qt
16.0 gal
.5 qt
1.7 qt
6.0 gal

407-5 Low-Density Epoxy Filler for fairing
407 Low-Density
407-5
407-15
407-B
4.0 oz
12.0 oz
14.0 lb
.5 qt
1.7 qt
6.0 gal
.4 qt
1.3 qt
4.8 gal
.3 qt
1.0 qt
3.7 gal

410-2 Microlight Epoxy Filler for fairing
401 Microlight
410-2
410-7
410-B
2.0 oz
5.0 oz
4.0 lb
1.2 qt
3.0 qt
8.9 gal
.9 qt
2.4 qt
7.2 gal
7 qt
1.8 qt
5.6 gal