Cleaning Different Types of Stonework
By Silas Finch
Different types of stone require different strengths of cleaning products and will put up with different levels of strong-arming. Frail limestone can crumble before your very eyes if abused by a steel brush but granite will laugh off the hardest scrubbing.
Obviously the first thing to do is make sure you know the type of stone your dealing with. There are many books you can purchase or find at a decent library that will help if you are unsure. There is an article on this website on the subject, you can read it here.
You will notice that in all the tips below I suggest using regular dish soap for cleaning stonework. There are specially made stone soaps that can be found in most hardware stores. Some people claim that it is preferable to regular soap because it is either safer or more effective than dish soap. Personally I notice no difference and dish soap is cheaper.
Granite The surface of granite is non-porous and so dirt, grime, and the like will not penetrate its surface or be absorbed by the stone. This makes granite and other very hard minerals very easy to clean. With stone as hard as this it is difficult to make mistakes, grab a good stiff brush, several gallons of soapy water, and get to work. If the piece is particularly filthy it will be necessary to add a small proportion of ammonia.
Limestone, sandstone, and other soft stone It is not wise to scrub sedimentary stonework at all if you can avoid it. The best approach is to soak the piece with water in hopes of softening whatever layers of grime and organic material the piece has accumulated. Usually the lawn sprinkler is the best choice but I have used the bathroom shower. You may have to leave the water on for several hours so make sure you aren't going to wind up with a mess.
When you have to scrub picking a brush can be difficult, you want one that is both stiff enough to function and yet soft enough not to damage the piece unnecessarily. The rule of thumb: small and plastic. Once you got your brush use a bucket of warm water, a little dish soap, and a generous 3/4cup of ammonia to remove any remaining dirt.
Marble Cleaning marble is an relatively involved process. Marble is obviously quite hard but it is also very porous. It absorbs environmental contaminants, wax, alcohol, and yes, even soap. Any of which can permanently affect the color of a marble antique. Water left behind during cleaning can create stains by allowing dissolved organic materials sink into the surface of the marble. So while cleaning marble statue isn't difficult it is necessary to be patient and meticulous.
Before putting any king of water or cleaning agent on the marble use a small brush to wisk away any materials from the nooks and crannies. Be diligent, the more work you do now the less will follow when washing.
As always, use liquid dishwashing detergent mixed with warm water. Throw that brush away and get a new clean sponge for your marble. Start at the bottom and clean upwards, this prevents streaks and limits the amount of soap left behind.
You must thoroughly rinse the piece to remove all soap residues. Then dry the marble as thoroughly as possible with a soft clean cloth. If the piece is small and intricately carved consider using a hair dryer. It is very important not to leave any water on your marble if you can avoid it.
Silas Finch is a freelance writer and regular contributor to Collectible Antiques Etc. He can be reach at Content and Solutions or by email at silas@collectibleantiquesetc.com.