In the field of plastics processing, the decoration of plastic parts plays an important role. It is not limited to aesthetics; it also meets functional needs, such as protection against scratches, UV rays, or graffiti, as well as product differentiation. Today, there are many decoration techniques suited to the demands of different market sectors.
Summary Table of Different Types of Decorations in Plastics Processing:
| Technique | Principle | Visual Appearance | Advantages | Disadvantages | Typical Applications |
| Mold Texturing | Texture applied directly in the mold (chemically or mechanically) Here are the classification methods: VDI 3400: Uses a numerical scale from VDI 0 to VDI 45. Higher values indicate a rougher surface. SPI: Classifies finishes from A1 (very glossy) to D3 (deep matte), based on polishing method. Charmille: Finishes obtained by Electrical Discharge Machining (EDM), often used to create specific textures on molds. | Matte, textured, leather-like, sandblasted, technical | Durable, economical (no post-injection step), hides defects and fingerprints, gives a “premium” appearance | Cannot be modified after injection | Visible parts, dashboards, housings |
| IML (In-Mold Labeling) / IMD (In-Mold Decoration) | Insertion of a decorative or functional film into the mold before injection | Printed, glossy, matte, holographic effect, transparent | Integrated into the part, high precision, resistant (wear, scratches), very high level of customization | Higher mold cost, longer injection cycle | Touch interfaces, complex decorations, home appliances, automotive |
| Painting | Application of paint after injection | Custom colors, matte or metallic effects | Custom finish, possible contrast | Requires surface preparation, prone to scratches if not varnished | Casings, design components, high-end finishes |
| Varnishing | Application of a protective varnish: UV varnish: fast curing, excellent resistance. Matte, satin, or glossy varnish: adapted visual finish. Anti-graffiti varnish: especially useful for publicly exposed parts, allows easy cleaning of marker or paint traces. | Transparent, satin or glossy | Protects against scratches, UV, solvents, humidity | Additional cost, sometimes requires multiple layers | Urban furniture, design parts, public equipment |
| Pad Printing / Screen Printing | Pattern printing: Pad printing (via tampon) -> curved or complex surfaces Screen printing (via stencil) -> flat surfaces | Fine, precise, two-color or monochrome | Low cost, fast, precise | Susceptible to wear | Logos, pictograms, symbols |
| Laser Engraving | Direct marking into the material via laser | Very fine, discreet, engraved, sometimes contrasted | Permanent, no disposable materials, precise | High initial machine cost, not suitable for all materials | Serial numbers, codes, permanent logos |
Comparison of Finishes Between VDI and SPI:
| Finish | VDI | SPI | Ra (µm) | Method |
| Very smooth | VDI 12 | A1 | ~0.40 | Diamond polishing |
| Satin | VDI 18 | B2 | ~0.80 | Paper polishing |
| Matte | VDI 24 | C3 | ~1.60 | Stone polishing |
| Very matte | VDI 33 | D2 | ~4.50 | Sandblasting |
| Rough | VDI 45 | D3 | ~18.00 | Heavy sandblasting |