In a varnish manufacturing plant, fumes were emitted during welding on a downed installation during summer works. A slag particle had entered cell C of the workshop, yielding anti-settling agents for nail polish, despite protective tarpaulins and water spraying in the mixing tank (empty) located beneath the welding. Flameless smoke was followed by a small flash and spread to the awaiting empty tanks in the same workshop by the shared evacuation system for solvent vapours. The employees activated the fire system (dry). The incident was quickly controlled, but the smouldering insulating panels on the roof started a fire in cell D behind a firewall. The maintenance manager and a plant technician flooded the tanks and premises in awaiting the arrival of fire-fighters from the neighbouring town. After having secured the safety of these cells, the insulating panels were removed and the solvent vapour extraction pipes dismantled and inspected. Property damage was limited and installation rehabilitation was estimated at less than €2,000. Given the quantities involved in the workshop (the presence of product residue on the walls of the tanks since it is very viscous, or a maximum of 10 kg on a 5-tonne tank), the consequences in terms of heat flux were also minor, thus avoiding the risk of a domino effect within the storage buildings. The facility was equipped with a pit for the processed water, and an independent stormwater drainage system could be transferred into the pit in the case of an incident. The set of valves required to isolate the site from the natural environment were quickly activated to avoid polluting the DORDOGNE River. The emission of smoke during the incident remained limited, and no disruption to traffic was observed on the secondary road passing in front of the site. The automatic fire extinction system was not activated because the incident did not generate sufficient heat for the detection system to trigger. However, the quick reaction of the staff in manually activating the fire extinction system helped minimise damage. The operator was set to examine the advantages of adding a smoke detector to the fire detection system. From then on, all interventions on hot spots above the tanks were to be carried out after having inerted the tanks with water. Lastly, the suspicion that slow burning spread due to piping or cabling in the wall between the two cells led the operator to verify the integrity of the fire walls within the plant building.