Concrete itself does not rust, but it readily soaks up orange streaks from metal: exposed rebar, metal gates and railings, garden furniture, drums, tools in the garage or a car parked against a wall for years. On light concrete these marks can be seen from a distance.
Home remedies such as vinegar or lemon juice work slowly, and acids can also damage the surface. It is simpler to loosen the stain with a product that penetrates the pores and then scrub it off.
What you will need
- WD-40 Multi-Use or WD-40 Trigger Pro for large areas
- a stiff scrubbing brush or wire brush
- a broom or vacuum for initial cleaning
- a garden hose with clean water
- gloves and safety glasses
Important: Test the product on a hidden area first, especially on painted or decorative concrete. Use a wire brush without heavy pressure so you do not wear away the top layer of concrete.
Step 1
Find the source and prepare the surface
Look at where the rust is coming from: if there is a metal canopy, drip edge or bracket above the stain, it will return unless that metal is protected. Sweep dust, leaves and sand off the concrete so the product reaches the stain and not the dirt.
Step 2
Apply WD-40 to the stains
Shake the can and spray the affected area generously with WD-40 Multi-Use using the wide spray. Make sure every stain is fully covered, but do not use more than necessary. For a garage wall, floor or long path, the WD-40 Trigger Pro is more convenient, with an even, wide spray pattern.
Step 3
Let it work
Leave it for 10-20 minutes. In that time the product penetrates the porous concrete and weakens the bond between the stain and the surface. Leave old, deep stains a little longer.
Step 4
Scrub the stains away
Once the stains start to fade, scrub them with a stiff brush or a wire brush, whose fine, hard bristles clean out the pores well. In most cases the stain comes off first time. If not, repeat the application and waiting time and scrub again as many times as needed.
Step 5
Rinse with water
Rinse the surface thoroughly with clean water from a hose so that no product or rusty dirt remains. Let the concrete dry and check the result in daylight: if any mark is left, treat that spot again.
Step 6
Protect nearby metal
To stop the stain returning, treat the metal that caused it: brackets, furniture legs, drum bottoms or the lower edge of a gate. Wipe them and apply a thin film of WD-40 Multi-Use to displace moisture and protect against rust.
Tip: If you regularly look after large areas of concrete or a fleet of vehicles in a garage, it is more economical to use
WD-40 5 l with a sprayer and refill a working bottle from it.
What next
Check concrete in spring after the snow melts and again in autumn, when most streaks appear. Treat nearby metal with WD-40 every few months and the stains will not come back.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».