The Designer’s Compass - Part 3: From Forest to Fired Clay: Re-evaluating Renewable and Mineral Resources

Designers often gravitate toward two fundamentally different material origins: resources derived from natural growth and those derived from the earth’s mineral base. Plant-based materials, like wood and paper, draw their appeal from renewability and carbon sequestration. Mineral-based materials, like ceramics and glass, offer unparalleled durability and inertness. Both categories present unique sustainability challenges that designers must navigate. Understanding the supply chain complexity, from forestry practices to high-heat manufacturing, allows designers to make informed choices.

The Renewable Power of Wood

Wood is a material essential to human history and contemporary product design. Wood’s fundamental advantage is its renewal; it is grown in forests, removing carbon from the atmosphere during its lifetime. Wood processing is relatively energy-efficient compared to materials requiring high heat, like metals and plastics. Many sawmills achieve additional efficiency by powering operations through burning by-products such as sawdust and bark.

Solid Wood: Carbon Sequestration and Longevity

Trees play a pivotal role in the fast carbon cycle, absorbing carbon dioxide (CO2) from the atmosphere. About half the volume of a tree consists of carbon pulled directly from the air. Wood materials often boast a negative carbon footprint because the sequestered carbon (biogenic CO2) stored inside the wood often exceeds the emissions generated during material processing.

Designers must address irresponsible harvesting, which creates enormous environmental issues. Felling too many trees severely impacts the global capacity for absorbing CO2. Poorly managed forests risk soil erosion and, eventually, desertification. Therefore, responsible forestry requires certifications like the FSC (Forest Stewardship Council) and PEFC (Programme for the Endorsement of Forest Certification). Both certifications promote forest preservation and biodiversity.

The International Union for Conservation of Nature (IUCN) maintains a red list of endangered wood species that designers must avoid. Different tree species have different growth rates; optimal harvesting can take anywhere from 40 to 150 years.

Solid wood demands careful consideration regarding finishes and end-of-life. Wood requires surface treatment to resist moisture, grease, and UV radiation. Designers should select water-based coatings, which emit fewer or no VOCs (volatile organic compounds), over traditional solvent-based lacquers. Wood treated with paint or lacquer is not widely recycled or compostable. This waste wood typically ends up in landfills or is burnt as biofuel. In 2018, Europe discarded 11 million tonnes of used furniture, with wood making up a significant proportion.

Engineered Wood: Utilizing Waste Streams

Engineered wood materials, such as plywood and MDF (Medium-Density Fibreboard), utilize post-industrial wood waste. These waste streams include sawdust, offcuts, and knotty timber unsuitable for solid wood production. Plywood consists of layered, glued veneers that offer enhanced tensile strength in specific directions. MDF is a composite of fine wood particles in a resin matrix, offering uniform mechanical properties in all directions.

Engineered wood has traditionally relied on formaldehyde-based resin binders. Urea-formaldehyde (UF) is particularly concerning, emitting formaldehyde long after manufacturing. Designers must specify NAF (No Added Formaldehyde) materials to minimize toxic emissions.

NAF materials use alternative adhesives like MDI (methylene diphenyl diisocyanate) or renewable plant-based resins. For example, FINSA Fibracolour NAF MDF has a process GWP of 0.5 kg CO2e / kg and a biogenic GWP of –2.6 kg CO2e / kg. NAF materials are classified as CARB 2 compliant, ensuring low formaldehyde VOC emissions.

HPLs (High-Pressure Laminates) are technically paper-based but use resin binders, often phenol-formaldehyde, for stiffness and durability. Dekodur® ECO-HPL offers a sustainable alternative by using a plant-based resin binder. HPLs are currently not recycled and are not biodegradable.

Cork composites use Post-Industrial Recycled (PIR) cork waste from wine stopper and footwear production. Expanded corkboard, made entirely of cork, achieves a combined process and biogenic GWP of –1.7 kg CO2e / kg. Cork composite materials using polyurethane binders are not compostable.

Paper: The Cycle of Fiber

Paper serves as a lightweight, renewable, and widely recyclable material. It is also inherently biodegradable. Papermaking relies on cellulose fiber, the basic building block found in every plant.

Recycling Challenges and Limitations

Recycled fiber comprised just over 50 per cent of the total amount of paper produced globally in 2019. Recycling paper reduces the need for virgin raw materials, energy, and water. However, recycling shortens the cellulose fibers, making recycled paper weaker than virgin material. Paper fiber can only be recycled four to six times before becoming too short for effective use. This necessitates a continuous input of virgin fiber to renew the material pool.

Paper recycling mills can process most printing inks, water-soluble coatings, and adhesives. Complex paper-based multilayered laminates require specialized recyclers. Designers must ensure paper coatings and adhesives do not compromise recyclability. The largest global volumes of recycled paper go into packaging, which averages 70% recycled content.

Recycled packaging paper offers a significantly lower environmental impact than virgin material. Virgin FSC packaging paper has a GWP of 1.3 kg CO2e / kg, while ArjoWiggins Cyclus Pack has a GWP of 0.5 kg CO2e / kg. Recycled paper can contain traces of petrochemical-based inks, requiring confirmation that specific grades are safe for food contact.

Structural Alternatives and Renewable Barriers

Barrier papers are emerging as a replacement for plastics in flexible packaging. They provide moisture and grease resistance without compromising the material’s inherent recyclability. UPM Confidio™ barrier paper has a GWP of 0.4 kg CO2e / kg.

Moulded paper pulp represents a newer generation of materials capable of replacing plastic moulded parts. Most moulded pulp products, such as egg cartons, use recycled raw materials, typically newspaper waste. PaperFoam®, a moulded paper foam, uses cellulose fiber mixed with industrial starch derived from potatoes. This allows for complex, injection-moulded parts. Recycled moulded paper pulp has a GWP of 0.4 kg CO2e / kg.

Alternative-fiber packaging paper reduces reliance on timber and addresses agricultural issues like stubble burning. PaperWise straw-based paper, derived from agricultural waste, has a GWP of 0.7 kg CO2e / kg. This compares favorably to virgin FSC packaging paper, which has a GWP of 1.3 kg CO2e / kg.

Ceramics and Glass: Challenges of Mineral Abundance

Ceramics and glass rely on mineral resources such as clay and sand. These minerals are classified as non-renewable, although they exist in abundance. Sand, crucial for glass production and construction cement, is technically non-renewable but replenished over time through erosion. However, the pace of mining often exceeds the time needed for replenishment, threatening rivers and coastlines.

Energy-Intensive Production and Low Recycling

Both ceramics and glass manufacturing are energy-intensive processes. Production requires high temperatures, relying primarily on traditional electric or gas-powered kilns and furnaces. Designers must look for suppliers who comply with certifications like the IRMA (Initiative for Responsible Mining Assurance) to promote responsible raw material extraction.

Ceramics recycling rates are currently low. Most post-consumer ceramic waste does not return to the production of new ceramic materials. In the European Union (EU), recycled materials account for only 3 to 4 per cent of all materials used in new buildings. Instead, ceramic construction waste, which amounts to roughly one third of all waste generated in the EU, is usually downcycled (used for road construction) or landfilled.

Innovative Waste-Based Ceramics

Innovative suppliers convert ceramic and construction waste into new products. Waste-based brick clay, used in products like StoneCycling’s WasteBasedBricks®, utilizes ground-up waste from demolition sites and sanitary ware. Virgin bricks have a GWP of 0.7 kg CO2e / kg, significantly higher than the 0.2 kg CO2e / kg GWP of WasteBasedBricks®.

Terrazzo is an old technique that recycles natural stone offcuts and ceramic waste, binding them with cement or resin. Herrljunga Terrazzo HT-LYKKE has a GWP of 0.2 kg CO2e / kg. Alusid SILICASTONE™ Terrazzo achieves a minimum recycled content of 98% by using recycled glass as a binder.

Sintered stone materials, such as Cosentino Dekton, use fine ceramic waste powder mixed with virgin material. While the sintering process is energy-intensive, using recycled materials reduces the consumption of virgin stone.

Glass: Recycling Success and Limits

Glass recycling is more established than ceramic recycling, but global rates remain relatively low. Globally, only about 21 per cent of the total glass produced in 2018 was recycled. Soda-lime glass, used for bottles, jars, and windows, accounts for approximately 90 per cent of global glass production.

Glass is infinitely recyclable in theory, with minimal loss of quality. Recycling glass helps reduce the environmental footprint of production. Using recycled glass allows glass furnaces to operate at lower temperatures, saving 2 to 3 per cent of energy for every 10 per cent of recycled glass added to the mix.

Recycled soda-lime packaging glass is the most widely recycled type of glass. Packaging glass with 80% recycled content has a GWP of 1 kg CO2e / kg, compared to 1.1 kg CO2e / kg for virgin glass.

Flat glass, used in windows and mirrors, is recycled at a lower rate. Flat glass manufacturers in Europe average about 25% recycled glass content. Saint-Gobain DIAMANT, a flat glass with 30% recycled content, has a GWP of 1.1 kg CO2e / kg, compared to 1.3 kg CO2e / kg for virgin flat glass.

Recycled fused glass, such as MAGNA Glaskeramik®, uses 100% waste glass that is heated and compressed into sheets. This material has a GWP of 1.5 kg CO2e / kg.

Borosilicate glass (Pyrex), valued for its thermal shock resistance, is currently recycled far less frequently than soda-lime glass. Virgin borosilicate glass has a GWP of 2.4 kg CO2e / kg. Recycled borosilicate glass can achieve a GWP of 1.9 kg CO2e / kg. Designers should choose borosilicate for high-performance thermal applications but recognize its recycling infrastructure remains small.