Biochar as a Carbon Black Replacement

Carbon black gives many manufactured products useful properties. It can add strength to rubber, provide black color, or help a material conduct electricity. The job it does depends on the product and the type of carbon black used.

Biochar gives manufacturers another way to bring renewable carbon into their products. It can serve as a filler, provide black color, or—with specialized processing—help conduct electricity.

Biochar is made by heating biomass, such as wood, with little or no oxygen. Its source and processing shape the properties it brings to a finished product. The research below shows how those properties can support different uses.

Fillers and reinforcement

A filler becomes part of a material and can change how it performs. In rubber, selected biochars can replace some carbon black while supporting strength and flexibility. In one study using a blend of natural and synthetic rubber, processed wood biochars replaced 30% of the carbon black with little change in tensile strength, a measure of strength when pulled.¹

In a study using guayule, a plant-based source of natural rubber, selected wood biochars replaced up to 60% of the carbon black. The resulting rubber was stronger, stretched farther before breaking, and absorbed more energy before breaking.²

Biochar also has a role in plastics and composites, which combine materials to achieve useful properties. Research with polypropylene, a common plastic, has explored biochar as a filler that changes stiffness, heat behavior, and electrical performance.³

Pigments and color

Biochar can also supply the black pigment that gives a product its color. Researchers have made printing inks using finely processed biochar, showing how biomass can become a useful alternative to fossil-derived pigments.⁴

For inks and coatings, color is only part of the picture. The size of the particles and how evenly they spread through the mixture help shape the final appearance. These properties connect the choice of biochar with the finish a manufacturer wants to achieve.⁴

Conductive applications

With the right processing, biochar can help materials conduct electricity. Researchers have demonstrated this in plastic composites and as an additive in certain battery electrodes.^{3, 5}

These uses give biochar a different job from adding strength or color. In the battery study, specially prepared biochar helped carry current in electrodes made with graphite. The material’s electrical properties and its contact with other ingredients were central to that role.⁵

Why partial replacement matters

Replacing some carbon black with biochar brings renewable carbon into a product and gives manufacturers another option for meeting their performance, sourcing, and cost goals.

The opportunity starts with the ingredient itself: carbon from biomass can take the place of some fossil-derived carbon. The useful replacement level follows the needs of the finished product, rather than one rate that applies to every material.⁶

CarbonMicro® 50 for manufactured products

Wakefield CarbonMicro® 50 is a fine biochar powder made from wood residuals for use in manufactured products. Wakefield can provide product specifications and supply information to help your team assess how it fits your materials and production needs.

Explore the CarbonMicro® 50 specification sheet, or visit Carbon Black Replacement for product and ordering information.

Sources and notes

1. Peterson. Biochar in polybutadiene/natural rubber 2020. Selected hardwood biochars were milled with 1% silica and tested in a 50/50 rubber blend. The 30% figure refers to the share of carbon black replaced, not the weight of the whole product. These were laboratory composites, not CM50 tests View Source ↩

2. Peterson and McMahan. Guayule rubber composites 2023. USDA’s technical abstract reports the 60% result for selected poplar and paulownia biochars in guayule rubber. It is specific to that study and does not establish a replacement rate for CM50 or other rubber systems View Source ↩

3. Noori et al. Polypropylene and biochar composites 2020. Spent-tea biochar produced at 1000°C was compared with carbon black in polypropylene. Electrical behavior involved high filler loading and permanent deformation under pressure; it does not establish general electrical equivalence or CM50 conductivity View Source ↩

4. Goh et al. Biochar pigments in flexographic inks 2021. The study used milled and dispersed pine- and currency-derived chars. Print density and pigment loading differed from the commercial comparison. Particle preparation, mineral content, dispersion, and substrate affected results. It did not test CM50 or establish performance across coating and printing systems View Source ↩

5. Kane et al. Conductive battery additives 2022. The publisher abstract reports successful use of selected lignin-derived biochar as a conductive additive in graphite anodes, but not as a direct replacement in the tested lithium iron phosphate cathodes. This concerns an additive, not replacement of graphite itself or a battery-grade CM50 claim View Source ↩

6. Virág et al. Wood biochar in natural rubber 2025. This study reported different strength and processing outcomes as substitution increased, illustrating why rates vary among materials. The research cited here does not establish universal cost savings or a finished-product carbon footprint View Source ↩