Rust

• 1). For light stains, mix 1 pound of oxalic acid per gallon of water, apply it to stained area, and wait 2 to 3 hours. Go to step 2. If it is a deep stain, go to step 3.
  
  
• 2). Scrub the surface with stiff brushes while rinsing with clear water.
  
  
• 3). For deep stains, make a poultice of 11 ounces sodium citrate, 2 quarts lukewarm water, and 2 quarts 12 ounces of glycerol mixed with diatomaceous earth (which looks and feels like talcum powder) or talc.
  
  
• 4). Apply this mixture to the stain with a trowel, and leave it for 2 to 3 days.
  
  The poultice should absorb the rust, and you can wipe up the waste material. Dispose of it properly.
  
  

Oil

• 1). If an oil stain is freshly spilled, wipe it up with an absorbent paper (shop rags are great for this). If the stain is old, go to step 2.
  
  
• 2). Cover the stain with a piece of flannel soaked in acetate.
  
  
• 3). Cover the flannel with a pane of glass or thin slab of concrete for 10 to 15 minutes.
  
  
• 4). Rinse.