Q.I own a condo and my renters have spilled coffee on the metal stairs. It was not washed off immediately. What do I use to remove the stain? I don’t want to damage the look of the stairs by creating another stain.
(Mr Franco Gala, 11 September 2008)
A.As the stain was not tackled immediately, it is hard to ascertain if the staining is actually the result of the tannin agents within the coffee – or from rusting that has occurred as a result of liquid remaining in contact with the metal stairs for a long period of time.
If the staining is due to coffee, then this can be tackled in a variety of ways. One of the safest is to use baking soda mixed into a paste with water. Using a cloth, apply this paste to the stain and gently rub it over the entire area. This method has worked well in removing coffee stains from the inside of metal flasks, without affecting the metal flask.
Standard household vinegar is another stain remover that is often suggested for use on coffee stains – a solution made up of 1 tablespoon white vinegar in 1 quart of cold water is applied to the stain and gently blotted out. However, remember that vinegar is a mild acid and therefore, there may be a risk of some metals corroding upon contact with vinegar, although the effect is probably very small, unless the metal is flooded in a bath of vinegar. If the metal is coated in a protective layer or of a non-reactive form (e.g.. stainless steel, which does not react to acid) then there should be no problem.
Commercial coffee stain removal products can also be used, although again, it is important to check the manufacturer’s instructions and to make sure that it is safe to use on metals.
If the stain is due to rust, then it will need to be treated to remove the rust particles. Always wear protective gloves during the stain removal process. Again, rust stains can be tackled with a DIY home solution of vinegar and water – or by using a commercial rust removing agent which contains oxalic acid. If using a rust removing agent, ensure that all instructions are strictly followed and all precautions have been taken. If a rust stain is severe, it may need to be gently buffed by a wire brush, pumice stone, scouring pad or sandpaper to remove the rust particles, before the bare spots can be primed with a rust resistant primer and even possibly repainted with a protective coating.