What is the fine-grained topic of the following text: In 1802, the company – which was founded by Josef Hardmuth in Vienna in 1790 and relocated to České Budějovice in 1848 – patented the first pencil lead made from a combination of kaolin and graphite, a technique that allowed for the hardness of the graphite to be varied. Only return the topic.
The invention of the first pencil lead made from a combination of kaolin and graphite by Josef Hardmuth's company.