Rigid SLA resins give you stiffness, fine detail, and dimensional accuracy; flexible resins behave like rubber for gaskets, grips, and soft-touch parts. Between them sits a spectrum of tough, durable, and elastic grades. Choosing well means matching resin properties to how the part is used — here is how.
Key Takeaways
- Rigid/standard resins — best detail and stiffness; brittle under impact.
- Tough/durable resins — more impact and fatigue resistance; engineering parts.
- Flexible/elastic resins — rubber-like, measured in Shore A hardness.
- Specialty grades: castable, dental, high-temp, biocompatible.
- Pick by function: looks, load, flex, or compliance.
What does the resin spectrum look like?
| Resin type | Feel | Best for |
|---|---|---|
| Standard / rigid | Hard, brittle | Visual models, fine detail |
| Tough / durable | Hard, impact-tolerant | Snap fits, functional parts |
| Flexible / elastic | Rubber-like (Shore A) | Gaskets, grips, seals |
| Castable / dental | Specialty | Jewellery casting, dental |
How to choose
If the part is for looks or fine geometry, use a rigid/standard resin. If it must take impact or flex without snapping, use tough/durable. If it must compress, seal, or feel soft, use a flexible resin and specify the Shore A hardness. For rubber-like FDM parts, also consider TPU — see TPU flexible printing. Full resin breakdown in SLA resin types.
Frequently Asked Questions
How do I specify flexibility?
By Shore A hardness — lower numbers are softer. Tell us the squeeze/feel you need and we''ll match a grade.
Are flexible resins as durable as TPU?
TPU generally has better tear/fatigue resistance; flexible resin gives finer detail. We''ll advise per use. Get a quote.