What Is C1S Paper?
C1S paper (Coated One Side), commonly referred to in packaging and publishing as SBS (Solid Bleached Sulfate) paperboard, features a high-grade mineral coating applied exclusively to one side of the sheet. The coated side provides a high-density, smooth surface for high-resolution graphics, rich CMYK printing, and specialty finishes (lamination, foil, spot UV).
The reverse (uncoated) side retains the natural tactile texture and high absorbency of raw bleached virgin wood fibers. This dual-sided structure makes C1S uniquely suitable for applications where one side demands vibrant visual branding while the reverse side requires functional handwriting receptivity, adhesive bonding, or structural rigidity.
C1S Bleached Ivory Board (SBS/FBB)
Triple-coated front provides an ultra-white, smooth canvas for rich CMYK graphics and lamination, while the fibrous uncoated back ensures superior PUR spine glue penetration.
Structural Packaging & Board Sleeves
Heavyweight multi-ply formulation engineered for zero cracking along score and crease lines. Essential for protective book slipcases, dust jacket wraps, and board book inner cores.
Key Benefits of C1S Paper
- High-Quality Front Printing: Coated surface yields ultra-sharp image contrast, vibrant colors, and smooth gradient transitions.
- Dual-Function Surface Structure: Combines a commercial exterior finish with a functional, write-on, glue-friendly interior surface.
- Cost-Effective Asymmetry: Eliminates the expense of two-sided coating when only one side is intended for customer display.
- High Tear & Folding Strength: Virgin sulfate pulp provides exceptional crease durability without cracking along the score lines.
Common Applications of C1S Paper
Softcover Book Covers
The standard for paperback covers (250–350 GSM). The coated exterior receives vibrant cover art and lamination, while the uncoated interior bonds permanently to hot-melt PUR spine adhesives.
Postcards & Greeting Cards
The front showcases high-definition photography with gloss/matte lamination, while the uncoated back enables smudge-free handwriting for messages and postage.
Packaging Folding Cartons
Used extensively for cosmetic packaging, retail slipcase sleeves, and game tuck boxes where structural rigidity and crisp folding are required.
Pocket Folders & Presentation Kits
Provides sturdy board caliper with die-cut folding durability, holding client proposals and corporate presentation inserts.
Precision Creasing & Die-Cut Folding
Our Swiss Bobst die-cutting lines score C1S boards along the grain to guarantee sharp 90-degree spine corners on paperback books, presentation folders, and collector slipcases without surface fiber rupture.
C1S Paper: Weight and Caliper Table
| Basis Weight (GSM) | Approximate US Basis (lb) | Caliper Thickness (μm) | Standard Book & Print Applications |
|---|---|---|---|
| 170 GSM | 115 lb Text / 63 lb Cover | 212 μm | Lightweight packaging inserts, presentation flyers, gatefold covers. |
| 210 GSM | 142 lb Text / 78 lb Cover | 272 μm | Standard mass-market paperback covers, lightweight book jackets. |
| 250 GSM | 169 lb Text / 92 lb Cover | 340 μm | International trade paperback covers, presentation folders. |
| 300 GSM | 203 lb Text / 111 lb Cover | 415 μm | Heavyweight trade paperbacks, standard postcards, retail hangtags. |
| 350 GSM | 236 lb Text / 130 lb Cover | 490 μm | Deluxe softcover covers, flashcards, luxury packaging cartons. |
| 400 GSM | 270 lb Text / 148 lb Cover | 555 μm | Children's board book core plies, heavy presentation boxes, rigid tuck cases. |
C1S vs. C2S Paper: Which Is Right for Your Project?
| Feature | C1S (Coated One Side) | C2S (Coated Two Sides) |
|---|---|---|
| Coating Layers | Coated on 1 side only; reverse is uncoated | Coated on both front and back sides |
| Printing Focus | High-density graphics on exterior; write-on interior | Equal high-resolution color fidelity on both sides |
| Tactile Surface | Smooth coated front, natural fibrous back | Uniform smooth coated feel on both sides |
| Adhesion & Gluing | Uncoated side bonds exceptionally well with PUR/EVA glue | Requires special glue or corona treatment for heavy box joints |
| Best For | Book covers, postcards, packaging cartons, folders | Interior art book pages, magazines, double-sided brochures |