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Dear colleagues & friends of recovered Carbon Black,
Welcome to our April 2005 dose of curated recovered Carbon Black and related news! The views and opinions in this newsletter are my own.
After an eventful month of March with Tire Technology Expo, AZuR-Netzwerk Partnertreffen and the ETRA European Tyre Recycling Association Conference, April is a quieter month where we all can dug in, progress our projects and reflect about rCB specifications (again).
We currently have7.120 subscribers and we also currently have 954 members in the LinkedIn rCB group Martin & friends: recovered Carbon Black "rCB" and tyre pyrolysis
👉 Listen to the audio version of the rCB News April 2025 (17:47 min)
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Overview
More thoughts on rCB specifications
rCB Asia & rCB Europe calls for papers, sponsoring, registration
Late addition: Some say Black Bear Carbon made the best rCB
More thoughts on rCB specifications
Beginnings
I had closed a consulting project with Bridgestone in May 2021. So it was way beyond April Fool's Day when on October 13th 2021, Bridgestone's VP Strategy & Transformation, Jake Ronsholt, called me. I was in bed with COVID. Jake said Bridgestone will do a presentation and position paper on recovered Carbon Black with Michelin (!). The two companies wanted to push the recycling agenda together and trigger end-of-life-tyre ("ELT") players to collaborate and define standards. And they did! And they engaged me to get them started with recovered Carbon Black.
rCB Rubber
The "rCB Rubber" workgroup founded by Michelin & Bridgestone presented twice in the Smithers recovered Carbon Black Conference, including a specifications and classification proposal and details about required certificates of analysis ("COA"). The group's work is continued by the tyre producers' association ETRMA.
ASTM
Fast forward to now. The ASTM D36.70 is working on recovered Carbon Black specifications and classification under work item WK84831. In the last two years, proposed classifications could not yet be agreed on by the ASTM ballot system (although I quite liked the first proposal with four analyses for the rCB classification)¹.
Comparison between the proposals
Very few comments have been published online on the rCB Rubber specifications and classification proposal. My personal view is that the rCB Rubber COAs are very detailed and instrumental for the rCB industry. They provide immediately applicable information on the required lot testing for rCB.
The rCB Rubber classification system has been kept more abstract and unrefined, maybe in the hope that the refinement would be added later by other parties. This has not happened completely. The ASTM workgroup D36.70 took up some but not all rCB Rubber classification suggestions and added one application property, the FT rheology.
Similarities of rCB Rubber grades, rCB Rubber COA and ASTM D36.70 1st proposal
Specification vs classification
My friend Jean-Paul BOUYSSET said at the ETRA conference 2025 "People confuse specifications with classification". Specifications define a material, while a classification defines differentiating features of the different grades of this material.
Spinning that thought further, I would select rCB application properties to define the classification, while I would put rCB material properties into the rCB specification in order to differentiate rCB from uncontrolled char.
For furnace carbon black, we can predict application properties (e.g. tensile strength) from the material properties (iodine surface and oil absorption number). This doe not work for rCB, because rCB is a composite material of several carbon blacks, clogged with carbonaceous residues and contaminated with inorganic "ash" material.
My thoughts & proposal
1️⃣ I propose to firm up the ASTM D8178-22 Standard Terminology Relating to Recovered Carbon Black (rCB) to clearly define rCB as an engineered material (like carbon black) in order to distinguish it from uncontrolled pyrolysis char.
2️⃣ Then, I propose to define a minimum specification standard for rCB including:
Maximum consistent ash content (e.g. 25%, ELT feedstock)
Minimum toluene transmittance (e.g. 80%, pyrolysis)
Pellet hardness range, maximum fines, maximum sieve residues (TBD, post processing)
Top cut particle size of the bound agglomerate (across several analysis methods, e.g. 10 µm, post processing)
3️⃣ Finally, I would define rCB grades by in-rubber application performance only. I personally am fine with the FT rheology analysis ASTM D8491, but I hear other voices lamenting about the high cost of an RPA device (some 200k€) and rather preferring a DMA analysis (which is fine for me as well). Maybe both systems / analyses could be considered in the grading?
4️⃣ A big future topic for me is process capability. Right now, the rCB industry has limited data as many rCB companies have not yet industrialised. This is changing quickly and already next year a rather huge additional production capacity will come on stream. Having rCB product in specification is one thing, but having an rCB process chain produce within the rCB specifications and well-centred between the specifications is on a different level.
There will be a time in the close future, when rCB production processes will be benchmarked by their process capability index "Cpk". I have not yet seen rCB production Cpks over 1. The reason for this is the lack of control on the ELT feedstock. But the industry evolves quickly and systems like the REGOM tyre sorting technology are helping to get better control of the composition of the ELT mix going into the pyrolysis reactor.
Process capability Cpk (source: Wikipedia)
¹ See more infos on the ASTM D36.70 rCB classification in my ETRA presentation
rCB Asia & rCB Europe calls for papers, sponsoring, registration
Recovered Carbon Black Europe is on 4-6 November 2025 in Barcelona, Spain. Recovered Carbon Black Asia 2025 is on 4-5 September 2025 in Bangkok, Thailand.
Both Smithers events together attract close to 500 delegates, the globally biggest community for recovered Carbon Black, tyre pyrolysis oil and tyre circularity!
And, both events have the call for papers still open and give you opportunities to place your brand on all conference materials through sponsoring.
PS: I am not business partner of the Carbon Black World 2025 on 12-13 May 2025 in Fort Worth, USA, but I will attend and present! Are you coming too? Let's plan for a coffee chat?
Late addition: Some say Black Bear Carbon made the best rCB
From a non-invasive ELT sorting technology over double-pyrolysing to double-milling, Black Bear Carbon did double of everything they could.
Black Bear Carbon had it all, the rCB, the raving fans, the customers and the brand.
Black Bear Carbon made indeed the best rCB anybody had ever seen at that point. So good that I still get enquiries for alternatives to Black Bear Carbon rCB. So good that Black Bear Carbon rCB almost ended up in the coating of the 2019 Audi e-tron.
And then there was a fire accident in the Nederweert plant on February 6th 2019 and Black Bear Carbon lost it all.
Ad van Oorschot was the face of Black Bear Carbon in most conferences and fairs. I am honoured to have become his friend.
Victor Vreeken was the courageous CEO in the last years, which proved to be financially tough years with the company (like many others who do not produce cash-flow) in a technical bankruptcy state.
Chris Twigg was the CTO in the early years, and I enjoyed regular Skypes with him when starting my consultancy. We were talking about top notch rCB. Chris once showed me water-dispersible rCB made with ozone post-treatment.
Richard Dikkers was the sales director and always present at the Tire Technology Expo.
There were of course many more colleagues.
Sometimes it is not enough to be the best. We need the money, too.
I am remembering Black Bear Carbon today. You have been rocking it. You were a nice client, an inspiring peer and a tough competitor to beat. Thank you for everything!
I hope I can capture some video footage with my friend Ad for inclusion in my rCB documentary series.
👆 Thank you for reading. Please leave a comment & ask questions!👇
Prospects for recovered Carbon Black 2024 - August 2025 update
Wolfersdorff Consulting Berlin
