Liquid Pigment Behavior During Filling and Solidification

Once pigments enter the filling stage, they have formed a relatively complete liquid system. At this stage, different types of pigments display clear differences in material behavior during filling, layering, drying, and the eventual formation of solid structures. The filling process cannot be viewed as a single pattern that all pigments follow. Standard artist pigments, metallic and chameleon pigments, and fluorescent pigments each follow distinct material evolution pathways.

1. Behavioral Differences Among Three Pigment Types During Filling and Drying

Standard Artist Pigments

• Layered filling and step-by-step drying: These pigments usually show clear characteristics of layered filling and layer-by-layer drying. The pan is not filled all at once; instead, multiple liquid layers form at different stages. The drying speed of each layer is not identical, influenced by the pigment's density, particle structure, and the state of the binder system.
• Layer re-activation: Fresh liquid pigment added later can soften the underlying layer that has already begun to dry, causing step-by-step changes in an ongoing drying process. As more layers are added, the internal cycles of wetting and re-activation increase, making the overall filling timeline longer.
• Fast surface drying and internal cavities: When the surface layer dries noticeably faster than the interior, a relatively smooth or complete skin can form on the outside while the inside remains moist or continues to shrink. This leads to internal structural cavities.
• Solid surface differences after drying: Once fully dry, different colors show the most obvious visual variation. Surfaces may display varying degrees of texture, bubble marks, shrinkage tracks, cracking, or local depressions.

Metallic and Chameleon Pigments

• Brief separation and recovery: Upon entering the pan, a brief separation between the liquid pigment and the binder system may be observed. As water evaporates and the binder system redistributes, a relatively stable solid structure eventually forms.
• Short timeline and structural stability: During subsequent filling, the underlying dried layer is rarely re-activated by new liquid. Internal layers remain relatively stable, internal cavities almost never form, and the overall filling timeline is generally shorter.
• Surface bubble marks: As the interior shrinks, trapped air bubbles gradually move upward and settle on the surface. While the surface rarely develops severe or complex cracking, local marks left by rising bubbles remain visible.

Fluorescent Pigments

• Bubble retention and migration: Air bubbles trapped in the liquid state do not disappear immediately after filling. As the material sits and dries, bubbles gradually move upward and gather near the top.
• Reduced internal density: A large number of bubbles remain trapped inside the material, causing the final solid structure to contain many internal voids and lowering its actual density. While the pan appears full from the outside, the interior contains significant space created by bubbles.
• Similarities to standard pigments: In terms of overall filling timeline, layered drying, shrinkage behavior, and surface post-drying structures (such as cracking and shrinkage marks), fluorescent pigments share high similarities with standard artist pigments.

2. Interface Contact, Shrinkage, and Overflow Behavior

Relationship with Pan Inner Walls

Light-colored plastic half pans serve not only as containers but also directly participate in pigment adhesion and staining:

• Surface adhesion vs. detachment: Some pigments only form a surface bond upon drying, while others separate or completely detach from the inner wall as they shrink.
• Internal material staining: Standard artist pigments and certain fluorescent pigments show stronger adhesion, penetrating the plastic wall material itself and causing irreversible staining. Metallic and chameleon pigments, by contrast, do not easily adhere to or penetrate the inner walls.

Volume Shrinkage Pathway

Every layer of liquid paint undergoes volume changes during drying, following this progression:

Liquid State → Volume Shrinkage → Local Detachment from Inner Walls → Solid Structure Formation

Overflow Residue Characteristics

When liquid paint exceeds the pan's capacity and spills down the outer walls, pigment behavior extends outside the container:

• Standard artist pigments: Spilled paint adheres strongly to surrounding surfaces, leaving hard-to-remove residue upon drying.
• Metallic and chameleon pigments: Due to lower viscosity, dried overflow residue is usually much easier to peel away from contact surfaces.

3. Ongoing Behavior and Environmental Response After Solidification

Full drying and complete filling do not mark the absolute end of pigment behavior. The solid structure simply enters a new phase, where ongoing changes occur under long-term storage and environmental exposure:

1. Re-activation by Humidity: In humid environments, certain standard artist pigments and fluorescent pigments can be re-activated by moisture, showing changes in physical state. Metallic and chameleon pigments rarely undergo re-activation under natural room humidity.
2. Late Effects of Heat and Light Exposure: Under prolonged high temperatures or exposure to sunlight, the solid surface may continue to undergo physical changes, developing fine surface textures or distinct cracking patterns.
3. Shifts in Physical State and Sensory Feedback:
   • Odor reduction: As pigments move from raw powder into the binder liquid and finally lose moisture during solid formation, their noticeable odor steadily fades.
   • End of airborne movement: Airborne dusting in the powder state and splattering in the liquid state disappear completely once the solid structure is established. The pigment becomes fixed within the solid matrix.
   • Water dependency: In water-free and dry conditions, solid paint maintains high structural stability. Water remains the primary external trigger for any dynamic state changes.

4. Summary of the Full Process Pathway

From liquid filling to long-term solid storage, the entire progression forms a continuous, dynamic pathway:

Liquid Pigment Enters Half Pan
↓
Layered Filling & Step-by-Step Drying
↓
Internal Shrinkage & Bubble Migration
↓
Partial Re-activation of Underlying Layers by Fresh Liquid
↓
Formation of Internal Cavities & Local Detachment
↓
Completion of Solidification & Appearance of Surface Textures/Cracks
↓
Varying Degrees of Pan Wall Adhesion or Staining
↓
Long-Term Storage Phase
↓
Late Changes Driven by Humidity, Temperature, and Light

The completion of filling and drying marks the transition from liquid behavior to long-term solid behavior. The entire journey—from the moment liquid first enters the pan to final solid formation, along with its post-solidification environmental responses—forms a complete record of pigment material behavior.

Over the years, the behavior of different pigments has been observed and recorded through the process of making handmade watercolor paints. Video recordings of part of this content have been archived in the pigment behavior records. The results of these pigment behaviors are organized and presented as art materials on VHaquarell.