Brewing Color: Pigment-Making and Artistic Applications of Recycled Tea Residues

Abstract

In contemporary academic discourse, sustainable design has emerged as a pivotal frontier in artistic and material research. With the global proliferation of milk tea consumption—particularly in Asian nations like China and Thailand—tea residues are generated in substantial quantities as a byproduct of beverage production. Although these residues lose their functional value for brewing after initial steeping, they retain significant potential as natural pigment sources. Guided by principles of "waste valorization" and sustainable design, this study aims to utilize tea residues as a foundational material to develop an ecologically oriented natural pigment system, exploring its practical applications and artistic expressions in painting.

The research employs an experimental art methodology as its primary approach, supported by theoretical frameworks from material aesthetics and ecological cycle theory. The study is structured in three phases: material exploration, pigment synthesis with medium adaptability testing, and artistic expression linked to theoretical analysis. The core objectives are threefold:

1.To assess the feasibility of repurposing tea residues as a secondary-use material.2.To synthesize pigment powders from tea residues through chemical reagent integration.3.To evaluate the synthesized tea-based pigments via practical painting trials.

In material selection, teas were categorized into four types: Chinese black tea, Chinese green tea, Thai black tea, and Thai green tea. Tea residue samples were collected from bubble tea shops, traditional teahouses, and other venues. All residues underwent initial dehydration, drying, crushing, labeling, and storage for subsequent experimental grouping.

During pigment synthesis, researchers combined tea residue samples with various chemical reagents. Key additives were classified into three categories:

Mordants: e.g., alum, to enhance pigment adhesion and color stability;

Color modifiers: e.g., copper sulfate, iron oxide solution, and citric acid, to adjust hue and tone;

Precipitants: e.g., slaked lime and edible alkali, to facilitate pigment precipitation for powder formation.

By modulating reaction time, pH levels, and reagent ratios, researchers synthesized diverse tea residue pigment precipitates with distinct color properties. All precipitates were vacuum-dried, air-flattened, ground, and sieved to yield fine, blendable pigment powders.

Subsequently, the study advanced to pigment-medium adaptability testing. Pigment powders were mixed with four adhesive types to suit different painting media:

1.Chinese painting pigments: mixed with gelatin or animal glue, suitable for rice paper and brushwork, emphasizing granular texture and ink wash effects;2.Watercolor pigments: blended with gum arabic, natural ox bile, and honey to enhance fluidity and transparency;3.Oil painting pigments: combined with linseed oil to form viscous paints for canvas applications;4.Crayon pigments: fused with beeswax and vegetable oil, then cooled and solidified for experimental art or educational use.

Building on pigment preparation, the study incorporated expert interviews and user surveys. Experts spanned fields including traditional Chinese pigment production, natural dye research, sustainable design, and ecological art education. Interviews focused on four dimensions: material innovation, color expressiveness, medium adaptability, and application potential. An online survey revealed that most respondents affirmed the sustainable attributes and material aesthetics of tea residue pigments, with nearly 70% expressing willingness to use such natural pigments in future artwork.

Following pigment development, painting experiments with study sketches were conducted to verify operability and expressiveness in creative processes. A one-year color stability test showed:

1.Most colors remained stable in dry, room-temperature environments;2.Lighter tones (e.g., green and yellow) exhibited slight fading after 12 months, though barely noticeable;3.Pigment stability was optimized through chemical reagent and adhesive integration;4.Crayon pigments demonstrated comparable stability under identical conditions.

Notably, chemical reagents in this study were used not to enhance chromatic vibrancy but to improve pigment stability and preservation for long-term artistic use. For future directions, three recommendations were proposed:

1.Expand adaptability testing on diverse surfaces (e.g., fabric, wood, plastic);2.Extend color preservation testing cycles with biannual fading documentation;3.Compare chromatic vividness against commercial standard pigments to establish visual evaluation metrics.

In conclusion, this study demonstrates the feasibility and aesthetic potential of tea residues as sustainable pigment materials through systematic recycling, experimentation, and design. Tea residue pigments represent not only sustainable material reconstruction but also an artistic exploration of human-nature-material relationships. The research methodology and design framework offer a replicable paradigm for advancing waste-to-art transformations.

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