Surface Finish Options
This page explains the surface finish options available for our composite sandwich panels and how each finish is intended to be used.
Surface finishes are defined by function, not appearance, unless explicitly stated as cosmetic.
Class A — Cosmetic Surface (Cosmetic Range Only)
Class A is our cosmetic surface finish, intended for applications where visual appearance is important.
- Smooth, uniform, cosmetic-quality surface
- Controlled appearance suitable for visible installations
- Intended for external, customer-facing, or presentation surfaces
Availability
Class A is only supplied as part of an A/B combination.
- A / B – Cosmetic face on one side, peel-ply bonding face on the reverse
The reverse face is always supplied as Class B (peel ply) to allow reliable bonding or structural integration during assembly.
Class A is not available as A/A, A/C, or A/D.
Class B — Peel Ply (Bonding-Ready)
- Finished with peel ply removed after cure
- Produces a clean, textured surface optimised for bonding
- No additional surface preparation required prior to adhesive bonding
Typical uses:
- Secondary bonding operations
- Bonded inserts, frames, ribs, or brackets
- Structural assembly
Class C — Tool Surface (Moulded Smooth)
- Formed directly against the mould/tool surface
- Smooth but not cosmetic (may show light witness marks or print-through)
- Closed surface suitable for sealing and machining
Typical uses:
- External structural faces
- Gasket and seal interfaces
- Surfaces requiring post-cure machining
Class D — Textured / Hygienic Surface
- Smooth, closed, lightly textured surface
- Designed to be washable and contamination-resistant
- Not cosmetic
Typical uses:
- Laboratory and cleanroom environments
- Areas requiring routine cleaning
- Surfaces where exposed fibres must be avoided
Surface Finish Class Comparison
| Class | Description | Appearance | Primary Purpose | Typical Uses | Bonding Ready | Cosmetic |
|---|---|---|---|---|---|---|
| A | Cosmetic surface (cosmetic range only) | Smooth, uniform, controlled | Visual appearance on exposed faces | Visible panels, enclosures, covers | No (reverse is B) | Yes |
| B | Peel ply surface | Textured | Structural bonding | Secondary bonding, inserts, frames | Yes | No |
| C | Tool surface (moulded smooth) | Smooth but non-cosmetic | Sealing, machining, dimensional accuracy | Gasket interfaces, machined features | No | No |
| D | Textured / hygienic surface | Smooth, lightly textured | Cleanability, contamination control | Labs, cleanrooms, washable surfaces | No | No |
Allowed Finish Combinations
| Combination | Typical Application |
|---|---|
| A / B | Cosmetic external face with bonded reverse |
| C / C | Structural panel with sealed faces both sides |
| C / B | External tool face with bonded internal face |
| C / D | Sealed external face with cleanable internal face |
| B / B | Fully bonding-ready panel |
| D / D | Fully cleanable panel |
Note: Class A is only available as A / B.
UV Stability and Environmental Exposure (Important)
Unless explicitly specified otherwise, all surface finishes are not UV stable.
For applications involving outdoor exposure, direct or indirect sunlight, or long-term exposure to artificial UV sources,
a suitable protective coating, paint, or surface treatment must be applied by the customer to prevent UV degradation,
discolouration, or surface ageing.
If UV stability is required, this must be specified at the quotation stage so appropriate materials or surface treatments can be discussed.
Choosing the Right Finish
- Is one face visible and cosmetic? → Class A / B
- Will a face be bonded to another structure? → Class B
- Will a face interface with seals or gaskets? → Class C
- Will a face require cleaning or contamination control? → Class D
If no finish is specified, we can recommend a suitable option based on your application.
Notes
- Cosmetic control applies only to Class A surfaces.
- All other finishes are structural and functional.
- Minor surface marks do not affect mechanical performance.