Designation
Where to buy| Item | Value |
|---|---|
| Designation | Resin fillers |
| Class | Composites |
| Type | resin fillers |
The common fillers
| Filler | What it is | What it does to the mix | Typical use |
|---|---|---|---|
| Colloidal silica (406) | Silicon dioxide powder; bulk density about 50 g/L | Thickens and controls viscosity; stops runoff on vertical and overhead joints; raises abrasion resistance. The most versatile filler | Bonding, gap filling, fillets; blended with other fillers in fairing mixes |
| Microfibres (403) | Milled cotton fibre | Holds resin in the joint, so porous surfaces do not starve it | Bonding wood and glass fibre; gap filling |
| High-density filler (404) | Mineral powder | For the highest properties where hardware is bonded under cyclic load | Bonding hardware; strong fillets |
| Filleting blend (405) | Wood pulp fibre, brown | Smooth fillets that need little sanding; colours other fillers | Fillets on wood with a natural finish |
| Low-density filler (407) | Phenolic microballoons, about 50 microns; bulk density about 100 g/L | Lower density; cosmetic fillets and fills; takes up moisture, so keep the tub airtight | Fillets and fairing; softer adhesives only |
| Microspheres (409) | Hollow glass spheres, 40 to 80 microns | Lower density, but harder; the mix is noticeably harder to sand | Fairing where hardness matters |
| Microlight (410) | Hollow glass spheres, about 50 g/L | Lightest; mixes easily and is about 30 % easier to sand than 407; feathers to a fine edge | Fairing large areas. Not under dark paint or on hot surfaces |
WEST SYSTEM, Filler Descriptions and Uses (Version A, 05/04) and the 406 and 410 technical data sheets. WEST SYSTEM groups 403 to 406 as high-density fillers that add strength, and 407, 409 and 410 as low-density fillers for fairing.
What it does to the cured weight
| Mix (105 resin / 206 hardener) | Cured density | Notes |
|---|---|---|
| 406 colloidal silica, mayonnaise | 65 lb/ft³ | Shore D hardness 80; compression strength 8,500 psi (406 data sheet) |
| 410 Microlight, catsup | 33 lb/ft³ (0.53 g/cm³) | 410 data sheet |
| 410 Microlight, mayonnaise | 29 lb/ft³ (0.46 g/cm³) | 410 data sheet |
| 410 Microlight, peanut butter | 27 lb/ft³ (0.43 g/cm³) | Sands and carves like basswood (410 data sheet) |
WEST SYSTEM 406 Colloidal Silica Technical Data Sheet (2 October 2009) and 410 Microlight Filler Technical Data Sheet. Typical values for these mixes only.
Notes from the guide
- The manual governs. A repair uses the filler the SRM or the resin maker names.
- One maker's sheets. Density, strength and consistency figures are typical values for WEST SYSTEM 105 resin with 206 hardener and the stated filler. Other makers' resins and fillers differ.
- No ratios. The sources give none for aircraft potting or fairing mixes.
Where to buy
AmericaDistributor coming soonOur partner for this region is on its way
EuropeDistributor coming soonOur partner for this region is on its way
OceaniaDistributor coming soonOur partner for this region is on its way
Distributors coming soon.
Sources
- WEST SYSTEM, Filler Descriptions and Uses, Version A (05/04) — Filler groups; 403 to 410 descriptions, composition, particle size and bulk density; 407 moisture; 409 harder to sand; 410 about 30 % easier to sand and not for dark paint or hot surfaces.
- WEST SYSTEM, 406 Colloidal Silica Technical Data Sheet (2 October 2009) — Use, consistencies, no strict formula, cured properties of a 105/206/406 mayonnaise mix.
- WEST SYSTEM, 410 Microlight Filler Technical Data Sheet — Cured density by consistency; buying guide (volume times 2.6).
- FAA-H-8083-31B, AMT Handbook — Airframe, Volume 1, Chapter 7 — p. 7-34, potting compound fillers, hard points, weight and balance.
Educational reference only. not approved data. Always consult the applicable SRM, AMM, or AC 43.13-1B and your certifying authority.