Material Selection

Create a Bill of Materials

Creating a Bill of Materials (often referred to as a “BOM”) is a good way to get an overview of all the different materials in a product. You can use this template as a guide. Start this exercise with a full parts list of your product, identify the materials that make up each part, and the chemicals within each material. Alternatively, in order to complete this method, you can also focus on one material of choice.

• List all the separate parts
• Identify all the materials
• Explore the chemicals used in each material

Assign a Generic Material Type

To understand more about the materials in each part, it is useful to assign a generic material type for each homogeneous material (see below). Examples include but are not limited to:

• Metal
• Plastic
• Plastic/metal composite (see example below)
• Dyed textile
• Solvent
• Wood
• Fabric or fibre
• Glass
• Foam
• Glue
• Finish

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Classify the Type of Cycle

After you have identified the generic material type in the previous step, homogeneous materials can be classified as either suitable for a biological cycle or a technical cycle. Designating a material as suitable for the biological or technical cycle depends upon what happens to a product after the use phase.

Materials suitable for a technical cycle cannot be consumed or otherwise processed by a biological system. Metals and plastics are examples of technical materials. These can be dismantled and reused, or physically or chemically transformed after their use phase.

Materials suitable for a biological cycle are designed to return to the environment during or after their use phase. Wood, cotton fibre and paper are examples of biological materials.

Start with assigning each generic material to the appropriate cycle. This will help later in the method as you consider optimising the product for circularity.

Dig Deeper

To truly understand whether a material is safe for humans and the environment, you need to know its chemical composition. This information is often regarded as the intellectual property of its supplier and thus not easily accessible. It is therefore important to build cooperation and trust within your supply chain.  

• Start by identifying the highest volume materials you use, and their suppliers
• Explore how you can receive more information from suppliers on the chemical composition of their materials and components
• Ask your suppliers if they are aware of any restricted substances or chemicals of concern in their materials or products
  

When in conversation with a supplier, they may send a Material Safety Data Sheet (MSDS). These data sheets, required by the U.S. Occupational Safety and Health Administration (OSHA) for all products, and sometimes used globally, are designed to address occupational safety only and usually provide an incomplete assessment of the chemical hazards in a product. Further exploration is needed to fully understand what’s in it and what the impacts are.

• If they are reluctant to share information, ask if they would be willing to do so if an NDA were available, either with you directly, or with a third party.
• In the Circular Design Guide method Safe & Circular Moving Forward with Materials, you will explore what you can do in order to make safe and circular material choices a driver for innovation in your design process.

Materials Screening

When you have more visibility on the chemical composition of a material, you can start screening it using the MaterialWise tool that will provide crucial information about known hazards.

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Regrettable Substitution

Substituting one chemical for another isn’t always straightforward, and you need to research the alternatives properly before making changes, as Matteo Kausch PhD from the Cradle to Cradle Products Innovation Institute explains:

Highlight all chemicals of concern that need to be eliminated in the design. When you find a chemical of concern, look for ways to design it out through Safe & Circular Product Redesign Workshop or have a look at the Safe & Circular Strategy Cards.

Feedstock Selection

Another important consideration when it comes to selecting safe and circular materials is determining where they come from, or how they are sourced, also referred to as feedstock selection. Because of the possible negative impacts on the environment and local communities from raw material extraction, selection of feedstock from recycled, reused, or properly managed renewable resources is ideal as they avoid such impacts.

If your material is part of a technical cycle, explore how it can be sourced with circularity in mind:

• Can this material be derived from waste from another industrial process?
• Is it possible to derive it from post-consumer waste?
• For both these options: has the waste stream been properly defined to avoid the risk of future harm?
  

If your material is part of a biological cycle, explore how this material can be sourced in an ecologically responsible and renewable manner:

• Can this material be also derived from waste, such as agricultural byproducts or food waste?

• Can resource extraction occur while maintaining biodiversity and supporting critical ecosystems?
• Does consumption of this material occur at a slower rate than the resource can regenerate?
• Is there proof that these materials are responsibly managed for environmental, social and economic benefits? Certification programmes could include FSC (Forest Stewardship Council), PEFC (Programme for the Endorsement of Forest Certification) and the Sustainable Agriculture Standard.
  

Circular Design

When you have selected a safe material and considered its life cycle impacts, explore how the product containing the material would fit in a circular design:

• Will this material be combined with other materials or chemicals in the product? Can these materials be easily separated?
• How durable is the material for the expected uses of the product?
• What is the expected lifetime of use of the product containing the material? Will it require repair or maintenance?
• How can the value of the material be recovered after the use phase of the product?  

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After-Use Phase

When you have selected a safe material and considered its circular design, you can then reflect on what will happen to the product after its use phase.

For technical materials:

• What is needed to recover the product, component and/or material? This could include communication with the customer and coordinating and collaborating with partners.
• How can the design of the product enable the materials to be cycled? One example is designing the product for ease of disassembly
  

For biological materials, when the product reaches the end of use:

• Is the material designed so it can biodegrade safely?
• Does the material need some special process (such as composting or waste-water treatment), technology or infrastructure before it can return to the biological cycle?
  

For both technical and biological materials, consider whether any additives  reduce the ability to cycle the product in which they are found. For example, a label on a bottle can disrupt the bottle recycling process, or a coating on paper can inhibit its biodegradation. To explore this further, see Safe and Circular Materials Journey Mapping.