The city council is using permanent grease to mark thousands of drains.
Nearly a thousand covers have been stolen in the last eighteen months.
Scrap metal thieves are costing the taxpayer millions of pounds a year and causing chaos on roads and railways.
The activities of two thieves with a gold-coloured car were recorded on CCTV.
The driver checks to see if anyone's looking - as his accomplice loads the grid on to the back seat.
They then stole three more covers from the same road in the Erdington district of Birmingham.
The thieves drove off leaving the drain totally uncovered.
Metal theft is a growing problem across the Midlands which is happening because of the rising price of scrap.
To combat it, councils are using sprays on drain covers which leaves an indelible mark on anyone who handles them - which can be traced back to the area of the theft.
Forensic sprays have already been tested in Derbyshire - and similar products are being used to protect water treatment plants in Leicestershire.