Probably the most frequently asked questions on our Facebook group, Yacht Stewardess and Steward Tips, are marble and stone related. At the Monaco Yacht Show this year we visited several yachts that had not only sealed and unsealed marble onboard, but also onyx and petrified wood.
One yacht even had a 4 ton polished agate wall running alongside the staircase – one can only imagine the extremely challenging time the Stews will have keeping that high-gloss wall free of streaks, scratches and finger-prints.
For this column, I have called upon the expertise of Dawn Riordan from Galene Consultancy (formerly of DNC Interiors), an authority on marble and stone care who will share some of her care and maintenance tips with us.
Two types of marble showcased in the modernist Mies Van der Rohe pavilion, Barcelona.
Which Types of Stone do we See Onboard Yachts?
Natural stone can be classified into two general categories according to its composition:
Siliceous stone: Mainly silica or quartz-like particles (granite, slate, sandstone and quartzite). These stones are harder and tend to be resilient against etching and staining.
Calcareous stone: Composed mainly of calcium carbonate (marble, travertine, limestone, and onyx). Whatever cleaning and maintenance methods work on siliceous stone may not be suitable on calcareous surfaces. Due to the high calcium content of calcareous stones, it tends to be a much softer stone which will be more prone to etching, staining and scratching.
It is crucial to maintain careful records about the type, name, and origin of the stone on your yacht. The shipyard that commissioned the yacht can be of great assistance here. If no such records exist on board, you have two options:
1. Consult with a professional stone restoration specialist to help identify whether your stone is siliceous or calcareous.
2. Visual identification. While there are exceptions, the following characteristics are common in identifying various stones:
Granites have a distinct crystal pattern or small flecks with very little veining.
Limestone is typically grey, tan, or buff in colour. A distinguishing characteristic of many limestones is the presence of shell and/or fossil impressions.
Marbles are usually veined, fine-textured materials that come in virtually unlimited colours and hues.
Top Tip: On new build projects it is recommended that the yacht purchase an additional slab of stone for each type of stone onboard, for future replacement needs. Ensure you keep clear records of the location of the stone, indicating where the stone has been used, for easier identification for future crew. Slabs of marble and stone are very large and heavy, therefore the yard or stone supplier could possibly store the stone or perhaps your yacht has their own storage or containers to store the stone until it is required.
Distinctive Ruskeala marble from Russia
General Guidelines for Both Siliceous and Calcareous Stones:
Use solid coasters under all glasses, particularly those containing alcohol or citrus juices (be sure to coat the underside of the coaster with a non-slip/non-scratch material). Avoid using napkins because if any liquid spills and soaks into the napkin, it may end up permeating the stone.
Do not cut fruit or garnishes directly on your bar or galley counters. Many common foods (especially fruits) and drinks contain acids that will etch or dull the calcareous stone surface.
Do not place hot items right off a stove or out of an oven directly on the stone surface. Use trivets or mats under hot dishes and place mats or non-skid rubber under china, ceramics, silver, or other objects that can scratch the surface.
Check the base of dishes and vases ensuring they are smooth to avoid scratching the stone. If there are any sharp areas, sand smooth or cover with felt.
Use a tray for guest amenities/toiletries in the guest heads. Be sure to protect any trays, bowls or vases with a non-skid/no scratch protection underneath to avoid scratching of the surfaces. Apart from creating a lovely display for the toiletries, it will avoid acids from toiletries and perfumes damage the surface of the counter.
Sealed or Un-Sealed
Before sealing your stone, you first need to know if it has been previously treated. You can find this information either from the shipyard or the last restoration company that carried out work on board. This is another reason why it is important for all Chief Stews to keep thorough records of shipyard work done and by whom. If you have decided to treat your stone, make sure you understand the differences between the types of sealers and that you have discussed it with a stone care professional.
Topical Sealers are coatings (forming a film) designed to protect the surface of the stone against water, oil, and other contaminants. They are formulated from natural wax, acrylic, and other plastic compounds. When a topical sealer is applied, maintenance is often done on the sealer rather than the stone underneath. The sealer can easily be damaged, and would then need to be stripped and re-applied.
Impregnators are water- or solvent-based solutions that penetrate below the surface and become repellents. They are generally hydrophobic (water-repelling), but are also oleophobic (oil-repelling). They keep contaminants out, but do not stop the interior moisture from escaping. These products are considered “breathable”.
Top Tips for Sealing Stone: Avoid the use of waxes or other non-breathable protectors on stone, as these block the pores of the stone preventing it from breathing. Stone needs to breathe to avoid discoloration and drying out. Think of stone like your skin as it requires similarly gentle care and maintenance!
Identifying and Removing Stains
Oil-based stains: grease, cooking oil, cosmetics. Oil contamination darkens the stone and generally must be chemically dissolved. These stains must be removed with a poultice such as Stone Care International Granite and Stone Stain Remover.
Metal stains: Iron, rust, copper, bronze. This will cause an orange or brown stain and normally leave the shape of the staining object (think rusted screw on a marble counter). Copper and bronze stains will be green or muddy brown. These stains must be removed with a poultice such as Stone Care International Rust Remover or preferably treated by a stone care professional. Deep-seated, rusty stains are extremely difficult to remove and if the stone is permanently stained, may require replacing.
For the following stains we would generally recommend the following treatments:
Water spots and rings - surface accumulation of hard water:
It is advisable to use MB-11 Marble Polishing Powder and Etch Remover for light coloured stones.
Organic stains – coffee, tea, fruit, tobacco, food, urine, vomit, bird droppings:
May cause a pinkish-brown stain which sometimes disappears once the source has been removed.. For heavier stains, try Stone Care International Granite and Stone Stain Remover.
Biological stains – algae, mildew, lichen, moss, fungi:
You should purchase an anti-bacterial spray designed specifically for natural stone.
Call a local stone care professional to remove and assist.
Etch Marks & Burn Marks on Calcareous Stones
These include damage caused by milk, fruit juices, vinegar, wine and all liquids that are not PH neutral. They will etch and may even stain the stone. Once the spillage has been cleaned up with a dry cloth or kitchen paper, wash any residual spillage from the stone. Wet the surface with clear water and sprinkle with marble polishing powder. For light coloured stones we recommend MB-11 Marble Polishing Powder and Etch Remover.
For light surface etching, rub the powder into the stone with a damp cloth using pressure until the brilliance of the stone is returned. Always test in an inconspicuous area first and carefully follow the manufacturer’s instructions.
For deep etching, honing will be required. This must always be carried out by a reputable stone care professional.
Marble and Granite Care
Even though marble and granite stones are not the same, they are often finished/sealed/honed in the same way and require similar treatment, so we will discuss them in the same section.
There are three primary stone finishes:
A natural polished finish creates a glossy surface which reflects light and emphasises the colour and markings of the material. The natural shine and brilliance of the stone is enhanced; it is not artificially coated by polyurethane.
A honed finish is a satin or matte finish with relatively little or no reflection of light. This process is carried out by a stone care professional company.
A flamed finish is a rough-textured surface – this is commonly employed on marble and granite and used for sink tops, bath tops, shower floors, bar tops. It is a design choice, particularly practical for shower floors where it provides a non-skid surface.
It is important to have a regular cleaning and maintenance schedule on board for the cleaning and care of your marble and granite surfaces, especially high-traffic areas. If you currently do not have one, then an in-house cleaning and a professional restoration schedule should be implemented so that you keep the stone onboard to a high standard.
Q. Which products are best for cleaning marble?
The fewer products you use - the better for your stone! Stone should be cleaned with a soft brush or cotton rag to remove any heavy dust or residue. Wipe clean with a cloth and warm water and dry off with a dry cotton cloth. If you do decide to use a product, ensure that it is specifically for natural stone and test first in an inconspicuous area. For new builds, request that the shipyard provides you with the correct products or following a refit, ask your professional stone care company what product they recommend.
Top Tip: Gel Gloss© is a popular marble and stone cleaning product. Would it depend on the type of finish
on the marble? Yes, if it is a matte finish, it is better not to use Gel Gloss©. Many Stews use and are happy using this product, but another great product for maintenance is Brillux© - a water-based sealer designed
for stone surfaces (not suitable for floors).
Q. What can I do if my yacht’s marble is already damaged?
If the damage is light or superficial, use MB-11 Marble Polishing Powder and Etch Remover on light-coloured stone. Use Stone Care International Granite and Stone Stain Remover for deep stains. For heavier damage where the stone requires restoration, it is best to contact a stone care professional.
Marble & Granite Cleaning Do's
Floor of rippled turquoise marble
When the stone is new or following restoration, ask your stone care professional for their product recommendations and to suggest a sealing schedule. If you have no history of the stone or works carried out in the past, then we recommend a water-based sealant, which can be used every 8 – 12 weeks or when needed, depending on how often the yacht has guests.
It is always easier to maintain onboard if the marble and granite surfaces are sealed. Raw and exposed marble tends to ‘suck up’ stains and they are much harder to remove.
Having stone sealed or re-sealed is a relatively inexpensive and straightforward process, which can either be carried out by a professional company or by the crew. However, first ensure that you have the correct product and know how to use it.
Full honing and restoration is a more extensive and expensive process. The professional stone care company should properly protect all the surrounding areas of the yacht’s interior prior to beginning the honing/restoration process and carry out de-masking and clean-up once the restoration is completed.
A spray surface dressing like a Topical Polish/Shine Enhancer will make the shine really sparkle and provide a little protection. Gel Gloss© Granite and Natural Stone Polish is a good everyday product to use for cleaning.
Remove spills as soon as possible. Marble, limestone and onyx are much more sensitive than granite to acidic substances like wine, coffee, fruit juices, tomato sauce, sodas, toiletry products, vomit, urine, vinegar and cleaning products that can stain or dull the surface finish.
Use the correct cleaning cloth. It is important to use very soft cotton cleaning cloths on natural stone. The only cleaning products you should use on a regular basis are Gel Gloss© Granite and Natural Stone Polish or warm water and a mild soap specifically for cleaning marble. Using mild soaps that are not specifically for natural stone will not harm the stone, but consistent use will lead to a dull film covering the surface like soap scum does in a shower or bath.
For maintenance, a specially formulated natural stone sealer such as Brillux© should be used every 8 – 12 weeks.
Marble at the Musée des Arts Décoratifs, Strasbourg
Q. How do I remove a build-up of soap scum in the yacht shower?
I am a big fan of using a squeegee in the shower after the guests have showered in order to dry off the initial drops before starting to clean. You can also use chamois to remove the worst water prior to starting the cleaning process. However, over time, our yacht showers build up a layer of lime scale and soap scum.
How can I remove this without damaging the marble seal? Prevention is better than cure. If there is a build-up, then the stone should be professionally treated, allowing you to start afresh with an effective maintenance schedule. Gel Gloss© or Brillux© is ideal for shower walls, as the water beads up and reduces calcium and scum build up.
Dry dust the marble floors regularly. Use a clean, dry, non-treated dust-mop (like a Swiffer Duster© mop). If you are in an area where special dry mops are difficult to find, a few white cotton socks on your hands can also be used for a quick dry-mop. Be careful when using a vacuum cleaner. Worn brush heads or grit stuck in the wheels will scratch the surface.
For daily ‘wet cleaning’/wiping marble floors, we suggest a marble soap such as Stone Care International – Stone Floor Cleaner.
Foot traffic will also wear away the shiny surface of polished floors over time. Sand, dirt, and grit do the most damage to natural stone surfaces due to their abrasiveness. Runners in high-traffic areas will minimize this wear on the surface finish. This will help to minimize the sand, dirt, and grit that will scratch the stone floor. It is important to place non-skid fabric underneath such runners to prevent excessive slipping.
Normal maintenance involves periodic washing with clean, drinking water and neutral (pH 7) cleaners. Soap-free cleaners are recommended, because they minimize streaks and film. Mild, phosphate-free, biodegradable liquid dish-washing soaps or powders or stone soaps are acceptable if rinsing is thorough. Always use cleaners specifically for natural stone.
Method: Wet the stone surface with clean water. Using the cleaning solution, wash in small, overlapping sweeps. Rinse thoroughly with clean, potable water to remove all traces of soap or cleaner solution. Change the water in the rinse pail frequently. Dry with a soft cloth and allow to thoroughly air dry. Follow the manufacturer’s product instructions.
Marble Cleaning Don'ts
Do not use generic or acidic household cleaners of any kind. Many common household products contain acids, alkalis and other harmful chemicals and may cause damage to the marble surface and degrade the stone's sealer/finish.
Do not cover your stone walls and floors in the yacht shower with RainX©. Most products in regular supermarkets claiming to be ‘marble cleaners’ are too harsh and can cause damage. However, usually if the product states that it is specifically for natural marble – they will be fine to use.
Trying to save money by using a cheap, generic surface cleaner only ensures that you'll spend a lot more time and money on your marble maintenance in the long-run requiring expensive repairs or marble restoration. Don’t ever use vinegar, ammonia or any citrus cleaners. Unfortunately, most environmentally friendly products will contain some sort of citrus.
Most Stews are big fans of vinegar as a cleaning product, but this is extremely damaging on marble, limestone, onyx and granite. Vinegar is highly acidic and will etch or dull the stone surface. Acidic cleaners to be avoided include bathroom, tub and grout cleaners (like Cif©). These creams contain abrasives, ammonia, bleach and citrus acids that will scratch and dull the surface.
Don't sit or stand on marble and granite counter tops. These do not typically have a plywood backing and too much weight in one spot could cause the counter to crack.
This one is for our Engineers…
Don't use marble counter tops as a workbench. Marble is a soft stone; tools and screws will scratch or gouge the marble. It is crucial to protect the marble with a drop cloth/towel prior to placing tools or tool boxes on the surface. Also, if engineers need to use an acid for the shower drains or down the toilets, great care must be taken to ensure that the acid does not splash onto the marble.
If damage does occur and you need marble repair, you can rest easy knowing that restoration is possible in most cases. Damage to stone is rarely permanent like it is with most other surfaces.
Best and Safest Marble Cleaning Products
If in doubt, play simple and safe – use a soft cotton cloth and warm water.
Cleaning Tips for Marble: Ensure that the grouting or silicone bead is in good condition around all wet areas such as sink tops, baths, shower walls and shower floors. Replace as soon as any cracks or lifting occurs to avoid water ingress which will lead to greater problems.
Onyx, when banded white and black, is technically a form of agate, and sardonyx, which is a banded reddish and white chalcedony, is also technically a type of agate.
Onyx is a banded variety of the oxide mineral chalcedony. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands. The colours of its bands range across almost the whole spectrum (save some shades, such as purple or blue).
The accepted dictionary definition of onyx describes a solid black chalcedony, or a banded/layered black and white chalcedony. The term onyx is occasionally used to describe any engraved stone with a solid colour base, or it may describe any banded gemstone with parallel banding.
Cleaning tips for Onyx:
Onyx is a very sensitive stone. Follow the exact same do’s and don’ts as for marble.
Agate is a translucent variety of microcrystalline quartz. It is used as a semi-precious stone when it is of desirable quality and colour. Agate generally forms by the deposition of silica from groundwater in the cavities of igneous rocks. Hot pink, blue, or green colours in agate are always dyed. Agate deposits exist in Brazil, Argentina, Uruguay, Mexico, Poland, Botswana, India, Australia, and the United States.
A generally accepted requirement in the definition of agate is that it has to be banded. Deposits where agates are commercially mined are usually very extensive, thereby enabling this gemstone to be affordable and inexpensive. However, a fine and sharp banded pattern, combined with natural strong colouring, will quickly increase the cost and value of agate.
Agate is generally an inexpensive gemstone when used in jewelry. It is cut and polished into cabochons, and used as beads for necklaces and bracelets. Agate makes an exquisite ornamental stone, and is cut into slabs, animal carvings, ornate book ends, and small statues and figures. Ornaments such as snuff boxes and the like are also cut from Agate.
Cleaning tips for Agate:
It is advisable to only wipe the polished agate down with a chamois and then buff dry with an extremely soft cotton cloth like a flour sack cloth.
Follow the exact same do’s and don’ts as for marble.
Petrified wood used as an untreated wall tile, and as a polished side table
Stemming from the Greek word “petro” meaning rock or stone, petrified wood has a captivating and deceptive appearance. It is formed from crystal-like amalgamations of organic materials and minerals, slowly building up within the fossilised form of the original vegetation. It maintains the general appearance of wood while taking on the toughness and colour of stone.
First, the wood will have been covered in substances like volcanic ash, lava, or lake sediments. Being covered in a thick blanket of volcanic material and sediment prevents oxygen from getting to the wood and decaying it. At this point, a variety of minerals enter the wood, whether calcite, pyrite or marcasite, petrifying the wood.
Silica is typically the most common mineral, but others such as quartz can be prevalent too. When these minerals crystallize over the following millions of years, we are left with the multi-colored, crystal like substance known as petrified wood.
Cleaning tips for Petrified Wood:
Follow the exact same do’s and don’ts as for cleaning marble.
A Final Word:
Always - especially with stones – remember the golden rule: Know what you are cleaning PRIOR to attempting any cleaning methods! If you are unsure, ask a professional to come onboard to assist with identification and provide maintenance tips. Ensure products are specifically for natural stone and always test in an inconspicuous area first.
About the authors:
Isobel Odendaal is a yacht veteran with over 20 years yachting experience and co-owns a yacht training school, Super Yachting South Africa, where she has been training the Steward/esses and Chefs since 2008. The school is part of the PYA GUEST Program and Isobel is the only approved GUEST Trainer in South Africa. For more information about the GUEST programme for Steward/esses please visit: www.guest-program.com
Dawn Riordan was the co-owner and co-founder of DNC Interiors for the past 14 years. Upon seeing the need for solid interior training and advice, Dawn has recently established Galene Consultancy, a company focused on evaluating your interior stone, upholstery and wood or paint finishes and providing your crew with bespoke on-board theory and practical training, teaching crew the components of their interior, how to prevent damage, cleaning recommendations and how to maintain the yacht’s interior to the high standards required for the superyacht industry. Email: firstname.lastname@example.org
Photo credits: Mies Van der Rohe pavilion, Wikimedia Commons; Ruskeala marble, Wikimedia Commons; red marble, Alex Borland; turquoise marble floor, Max Pixel; marble at the Musée des Arts décoratifs, Amanda44 via Wikimedia Commons; red onyx, Wikimedia Commons; Petrified wood tile, modified, IndoGemstone; coffee table, modified, IndoGemstone.