Printing Paper Classification
Photo printing paper is primarily categorized into the following three types:
1. Swelling Type Paper
(RC Paper Base + PVA Coating)
- Characteristics:
- Not waterproof.
- High brightness.
- Suitable for pigment ink.
Swelling photo paper features a coating that swells when exposed to moisture after ink is applied. The colorant penetrates into the surface layer. This type typically has three layers:
- Protective Layer: The topmost layer.
- Ink-Absorbing Layer: The middle layer.
- Absorbing Layer: The bottom layer.
The paper’s base is equipped with an anti-curling and anti-static coating on the back. Its polymer coating fixes the ink, prevents dye spreading, and protects images from light and air pollution.
- Drying Time: Requires some drying time post-printing, as the solvent in the ink evaporates naturally.
- Limitations: Photos are susceptible to damage from water, moisture (e.g., fingerprints, cooking steam), and other environmental factors after printing.
2. Cast-Coated Photo Paper
(Photo Paper Base + Micron Silica Coating)
- Characteristics:
- Coating is waterproof.
- Compatible with dye ink; limited use with pigment ink.
- Brightness is slightly lower compared to swelling-type paper.
Features:
- Quick-drying, taking approximately 10 minutes to an hour.
- Poor-quality coatings may cause ink to spread or flow after printing.
Comparison:
- Cast-coated paper feels smooth initially, but pigment ink may float on the surface post-printing.
- RC waterproof photo paper absorbs ink quickly and retains brightness due to its nano-level coating.
- Swelling-type paper and cast-coated paper deform slightly after printing due to ink absorption, unlike RC waterproof photo paper.
3. Microporous Photo Paper (Gap Type)
(RC Photo Base + Nano-Grade Silica or Alumina Coating)
- Characteristics:
- Waterproof.
- Instant-drying.
- Suitable for both dye and pigment inks.
- High brightness.
Features:
The surface contains inert nano-scale particles (silica or alumina), forming fine micropores that absorb ink rapidly.
- Advantages:
- Immediate drying prevents smearing.
- Resists moisture effectively.
- Ideal for pigment inks, as these resist light and air pollution better than dyes.
Limitations:
Lacks a polymer coating for additional protection, making colorants vulnerable to air pollutants like ozone, sulfides, and nitrides.
Differences Between Photo Paper and Plain Paper
1. Plain Paper
Ordinary copy paper consists of plant fibers of varying lengths, arranged randomly. Its coarse surface features fine burrs.
- Ink Behavior:
When water-based dye ink is applied, the ink droplets penetrate the fiber gaps via capillary action. The chaotic arrangement of fibers causes ink to spread unevenly, resulting in blurry and distorted prints. - Water Resistance Issue:
Since many inkjet printers use water-based inks, prints on plain paper are prone to smudging and color bleeding, especially when exposed to water.
2. Photographic Paper
Photo paper is specifically designed for printing vivid and long-lasting photos.
- Composition:
It features a special coating on plain paper that enhances brightness, absorbs fine ink particles, and cures ink quickly. - Advantages:
- Produces vivid, durable colors.
- Resistant to ink penetration due to its harder texture.
- Suitable for high-resolution printing.
- Types:
- Glossy photo paper.
- Matte photo paper.
- Glossy paper.
- High-resolution paper (thicker photo paper).