Table 3. Overview of failure modes and fracture types from all lap shear tests.
| Recipe (mg) | Cohesive Failure | Adhesive Failure | Mixed Mode Failure | Brittle Fracture | Ductile Fracture |
|---|---|---|---|---|---|
| 250 rosin/250 beeswax | 5 | 5 | |||
| 250 rosin/250 beeswax/50 ochre | 3 | 2 | 5 | ||
| 250 rosin/250 beeswax/100 ochre | 2 | 3 | 5 | ||
| 250 rosin/250 beeswax/150 ochre | 1 | 4 | 5 | ||
| 300 rosin/200 beeswax | 5 | 4 | 1 | ||
| 300 rosin/200 beeswax/50 ochre | 1 | 4 | 5 | ||
| 300 rosin/200 beeswax/100 ochre | 1 | 4 | 5 | ||
| 300 rosin/200 beeswax/150 ochre | 3 | 2 | 5 | ||
| 350 rosin/150 beeswax | 2 | 3 | 5 | ||
| 350 rosin/150 beeswax/50 ochre | 2 | 3 | 4 | 1 | |
| 350 rosin/150 beeswax/100 ochre | 3 | 2 | 5 | ||
| 350 rosin/150 beeswax/150ochre | 1 | 4 | 5 | ||
| 400 rosin/100 beeswax | 5 | 5 | |||
| 400 rosin/100 beeswax/50 ochre | 3 | 2 | 5 | ||
| 400 rosin/100 beeswax/100 ochre | 3 | 2 | 5 | ||
| 400 rosin/100 beeswax/150 ochre | 5 | 5 | |||
| 500 rosin | - | - | - | - | - |
| 350 acacia gum/150 beeswax | 5 | 5 | |||
| 350 acacia gum/150 beeswax/150 ochre | 5 | 5 | |||
| 500 acacia gum | 5 | 5 | |||
| Total | 36 | 9 | 50 | 63 | 32 |
Most failures are either cohesive or mixed-mode, suggesting the property being measured was the cohesive strength of the adhesive, and not purely the bond strength to the substrate. Adhesives with <350 mg rosin tend to fail in a ductile manner, while those with ≥350 mg rosin tend to fail in a brittle manner. n = 5 for each recipe. Adhesive recipes are expressed by the mass of each ingredient (mg).