Galvanised steel is coated with a layer of zinc that leaves it highly resistant to rust. This coating also leaves it highly resistant to paint adhesion. If you need to remove an existing paint finish from galvanised steel, this characteristic should make the process relatively quick and painless. Unfortunately, properly prepared galvanised steel is pretreated with an acidic primer prior to painting. This coating makes the paint adhere firmly. In this case, you will have to employ a paint stripping solvent. Know the proper way to apply the solvent and carry out the appropriate safety precautions, or you could end up suffering dangerous consequences.
Eliminate as much paint as possible from exterior galvanised steel using a pressure washer. Wait 2 to 4 hours for the steel to dry. Skip this step if the steel is located indoors.
Scrape large pieces of failing paint from the galvanised steel using a putty knife. Use a wire brush to scrape paint from awkward, tight areas of the steel. Sand stubborn bits of paint from the galvanised steel using a coarse, low-grit sandpaper.
Put on a respirator if you are working indoors.
Place plastic dust sheets beneath the galvanised steel.
Apply paint stripping solvent to a 3 foot by 3 foot area of the galvanised steel using a 2- to 4-inch oil paintbrush.
Wait 60 seconds for the stripping solvent to loosen the paint. Remove remaining paint, using the putty knife, wire brush and 80-grit sandpaper.
Do not smoke while working with paint stripping solvent, or you could start a fire. Paint stripping solvents emit harmful fumes. Be sure to wear a respirator if you are working indoors.