Things You'll Need
Liquid dish soap
Distilled white vinegar
Lichen is a variety of fungus that grows in particularly humid climates. If you've left your fiberglass or aluminum outside, lichen will likely begin to grow on it. Remove the lichen as soon as possible to prevent it from growing out of control and taking excessive time to remove. Never use tough abrasives such as metal brushes or coarse steel wool to clean fiberglass, as it scratches easily. Never use abrasive tools or alkali cleaners such as baking soda to clean aluminum, as they will scratch the surface and can damage the color.
Removing Lichen from Aluminum
Mix 1 cup warm water with 1/4 tsp. liquid dish soap. Do not use dish soap that contains bleach, as it might damage the color of the aluminum.
Dampen a clean cloth with the mixture and place it over the aluminum.
Leave the cloth there for at least 10 minutes. This will completely soak the lichen stain and will make it easier to remove.
Remove the cloth and gently rub the surface with it to loosen the lichen.
Brush the lichen gently with a toothbrush until you've completely removed it.
Mix 1 cup hot water with 1 cup distilled white vinegar if the stains are still visible.
Soak a clean cloth in the mixture and lay it on the lichen stains. Let it sit for at least 10 minutes.
Remove the cloth and rub the stain away with the cloth. Brush the stain with the toothbrush until you've completely removed it.
Removing Lichen from Fiberglass
Mix 1 cup of warm water with 1/4 tsp liquid dish soap. Soak the lichen growth with the solution and let it sit for at least five minutes. This will give the solution time to loosen the stain.
Dip a clean toothbrush into the solution and then gently brush the lichen stain. Remove as much of the lichen stain as possible.
Add just enough water to 2 tbsp. baking soda to make a thick paste if the lichen stain is still visible. The paste should be the same consistency as toothpaste.
Gently brush the baking soda mixture into the lichen stain. The baking soda will act as a mild abrasive that is tough enough to remove lichen but soft enough not to scratch the fiberglass.
Rinse the area with clear water and dry it completely with a clean cloth.