Not all wax discs behave the same in the oven. Burnout shrinkage and contrast are the two numbers that decide your pressing fit.
Shrinkage
Quality CAD/CAM wax shrinks 0.1–0.3% on burnout — predictable enough to compensate in design. Generic wax can swing to 0.8%, and your pressed coping comes back loose.
Contrast
A high-contrast wax reads the margin crisply at the try-in photo; low-contrast wax blurs the finish line and invites an over-trim.
Pick by job
- Pressable copings: low-ash, low-shrink wax.
- Diagnostic wax-up: high-contrast wax.
- Complex bridges: a wax with stable thermal flow.
See the wax range split by ash and contrast grade.
Contrast is a workflow tool
A high-contrast blue wax reads the margin on a scanner without spray; a neutral wax needs scanning powder. Pick contrast by your scanner, not by habit.
| Wax | Shrinkage | Use |
|---|---|---|
| Hard, high-contrast | 0.1–0.2% | Veneers, inlays |
| Soft, neutral | 0.3–0.5% | Bulk copings |
Compensate in design
Add the shrinkage to the pattern's outer wall; a 0.2% miss on a 10 mm span is 20 µm — within press tolerance, but stack two errors and the coping is loose.