The non-emulsion side of film stock – the transparent cellulose or polyester substrate that carries the light-sensitive emulsion layer.
What is the Base Side?
The Base Side (Schichtträgerseite) is the back of the film material, onto which no light-sensitive emulsion is applied. It consists of a transparent base material and is the side that faces the lens when inserted correctly.
Film Construction
| Layer | Description |
|---|---|
| Protective Layer | Topmost layer, protects emulsion |
| Emulsion Layer | Light-sensitive silver halides |
| Adhesive Layer | Binds emulsion to base |
| Base (Support) | Transparent support |
| Anti-Halation | Prevents reflections |
Base Materials
| Material | Properties |
|---|---|
| Acetate (Cellulose) | Classic, shrinks over time |
| Polyester (PET) | Modern, dimensionally stable |
| Nitrate | Historical, flammable (no longer used) |
Distinguishing Base vs. Emulsion
| Method | Description |
|---|---|
| Optical | Base is shiny, emulsion is matte |
| Tactile | Base is smooth, emulsion is slightly rough |
| Notches | Kodak notches on the base side |
| Rolling Up | Emulsion on the inside of the roll |
Why is the Distinction Important?
| Problem | Consequence |
|---|---|
| Incorrect Insertion | Image is out of focus (focus on the wrong side) |
| Mirror Image | Text and movement are reversed |
| Perforation Damage | Scratches on the emulsion |
Correct Handling
| Rule | Description |
|---|---|
| Base Towards Lens | Standard insertion position |
| Emulsion Towards Gate | Contact with pressure plate |
| Cleanliness | Protect both sides |
| Gloves | Avoid fingerprints |
Base Side in Different Formats
| Format | Special Feature |
|---|---|
| 35mm | Standard insertion, notches as reference |
| 16mm | Perforations on one side only |
| 65/70mm | Larger base area |
| Super 8 | Cartridge prevents errors |
Optical Properties
| Property | Value |
|---|---|
| Transparency | >90% |
| Refractive Index | ~1.5 |
| Thickness | 0.125–0.14mm (base) |
| Total Thickness | 0.14–0.15mm (with emulsion) |
Quality Issues
| Problem | Cause |
|---|---|
| Scratches | Improper handling |
| Streaks | Chemical residues |
| Deformation | Heat, humidity |
| Breakage | Mechanical stress |
During Projection
| Aspect | Significance |
|---|---|
| Base Towards Projector | Light first passes through the base |
| Emulsion Towards Screen | Image is projected |
| Focus | On the emulsion plane |
Today
In the digital age, the Base Side is primarily relevant for film archives, restorations, and the small but active analog film community. Knowledge of film construction remains important for anyone working with historical material or current analog production.
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