Ceruse, structured through the holding Ceruse Investissement, is the parent of Groupe Lemer, a foundry group based in the Nantes area of western France that specialises in lead and aluminium casting. Operating under the historic Lemer and Dejoie names, it designs and manufactures radiation-protection solutions for the nuclear and medical-imaging sectors, alongside low-melting-point and technical alloys, security seals, and lead ballast for boating, diving and industrial uses. The group controls the full production chain from design to distribution and runs three production sites, all in the Nantes region. According to figures published around its 2025 change of ownership, the business generated roughly EUR 13.5 million in revenue with about 70 employees. Its positioning combines a niche in radiation shielding, where lead remains the reference material for absorbing ionising radiation, with a broader industrial and nautical casting franchise.

Ownership journey

The group traces its roots to Fonderie Lemer, founded in 1878 as a specialist in low-melting-point alloys, and Dejoie, founded in 1929 for security seals and aluminium parts, the two houses combining in 1988 to form the Lemer-Dejoie foundry near Nantes. In December 2016, the company's managers Laurent Lecole and Pascaline Lemer led a management buyout of the business, backed by Tikehau Capital investing through its Tikehau Private Equity Aerospace I fund. The transaction gave Tikehau a controlling position alongside the incoming management team, placing the foundry within the firm's aerospace and defence private-equity strategy. Tikehau exited in 2025 via a trade sale, and no further sponsor is disclosed on this sheet.

Under PE ownership

The 2016 buyout was intended to secure the business, structure its strategic segments and launch a growth dynamic under a stable ownership base. Over the holding period the group reinforced its position in historical end-markets while pushing innovation in radiation protection and technical alloys, the two areas where it holds the strongest differentiation. It also invested in industrial modernisation across its three Nantes-area plants, including new workshop equipment and a longer-term site upgrade programme. By the time of the 2025 exit the company was operating as a consolidated lead and aluminium foundry group with roughly EUR 13.5 million in revenue and about 70 staff, positioned to combine with a larger foundry platform.

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