Category: Natural Stone

I have been asked this question on more than one occasion, by several house-holders. Even more alarmingly, I have also been asked the same and similar questions by people in the industry. It is easy to see why; there are numerous TV shows, magazine articles and on-line DIY sites that recommend all manner of traditional remedies for all sorts of situations. Vinegar, lemon juice and many other household chemicals are frequently presented as wonder cleaners.

So is it all nonsense? Well, no, recently I saw the wonderful Kim and Aggie (How Clean Is Your House TV show in the UK) using a variety of home-made concoctions with great success. But, Kim and Aggie no-doubt know their stuff and that means knowing where not to use something as well. The danger is that substances like vinegar etc are pretty potent acids and they will quickly attack any acid-sensitive material.

Only recently, a very distraught person came to me with a stained marble floor. I was able to advise what to do remove the stains, but then he noticed some dull patches. These are etch-marks, caused by the action of an acid (orange juice, red wine etc). The acid in the contaminant has actually burned away the ‘polish’ in the stone. On closer inspection, the entire floor was dull, matt and with a yellow hue to its surface. On enquiring what had happened, I learned that after removing the stains, he had washed the whole floor with lemon juice! The citric acid had etched the whole surface, but as well as rendering the floor completely dull and lifeless, it also effectively increased the porosity of the stone at the surface, allowing the yellow colour of the lemon to get in and stain the floor.

The lesson here is to make sure you know and understand the type of cleaner you are using and also, know your stone. Unless you are an expert, never, use any form of acid on an acid-sensitive stone. So how do you know if your stone is acid-sensitive? Well stones made up of or containing calcium are usually acid-sensitive, the following is a general (but by no means exhaustive) list of popular materials that are high in calcium and therefore subject to attack by acidic cleaners:

· Marble

· Limestone

· Travertine

· Terrazzo

· Conglomerate Marble

· Grout and Cement-based concrete slabs and tiles

Having said this, there are always exceptions to the rules; it is generally considered that granite is not acid sensitive; hence granite is the usual choice for kitchen work tops rather than marble. However, these days you cannot take this as a given. With the explosion of imported stone from all over the world we are now seeing some stones that do not conform to the norm. There are some types of granites that do contain a tiny amount of calcium in the matrix (the fine grained material around the bigger crystals). There are also a number of stones that look and feel like granite that, geologically speaking are not strictly granite at all. We have seen a lot of so-called black granite that can have quite a violent reaction to even mild acidic compounds and unlike polished marble, it is not so easy to re-polish the etch out again.

So be warned and be careful, if you are in any doubt at all then find an off-cut or an inconspicuous area and test any cleaner for such reactions before you proceed.

Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.

Deep Cleaning

From time to time you may want to give the surface a thorough clean. The best way to achieve this would be to wash the granite with a good alkaline product like Heavy Duty Tile and Grout Cleaner. Bear in mind that this process is likely to take off any surface polishes that may have been applied, so they may need reapplying afterwards. There are three important words to remember when doing this: Dwell-time, Agitate & Rinse.

Step 1 – Apply the cleaner (mixed at say, 1 part to 5 parts water) and allow it to Dwell for 5 to 10 minutes

Step 2 – Now Agitate (scrub) the surface with a non-abrasive white nylon pad or similar.

Step 3 – Now mop up the cleaning solution with paper towels and finally the all important Rinse. It is the rinsing with fresh, clean water that removes the last of any dirt and along with any trace of detergent, which if simply left to dry on the surface can leave a dull residue. For a great finish, buff off with a cotton towel.

Removing Stains

If after a deep clean there are some deeply ingrained stains, then all may not be lost; Certain stains such as oil or grease can be effectively ‘pulled’ from the granite by using a poultice. Poultice Stain Remover by Aqua Mix is one such product; it can be mixed into a paste with water, or other cleaners to make a very effective poultice. Pour the mixed paste onto the stain, spread it out so it is about 20% bigger than the stain itself and cover with plastic film, then leave it for 24 hours, remove the film and leave it until dry. Then carefully remove the (now dry) poultice using a plastic scraper, if the stain has gone just rinse the work top and throw away the poultice (sometimes you can see the stain, transferred to the poultice!) occasionally for some stains you may need to repeat the process.

Just one small word of caution; some granite work-top sellers are, unfortunately selling inferior quality stone, sometimes this type of stone is not real granite at all, there are even some out there that have been treated with a dye to make them appear uniform in colour for example, some of these may be adversely affected by certain cleaning regimes, including the use of poultices. If you suspect that you may have this type of stone, or cannot ascertain if it is the genuine article, then proceed with caution, test an inconspicuous area first to make sure it is compatible.

Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.