Rust stains on marble can be cleaned using a poultice, which is a paste formed from a mixture of materials. While there are many ways to create a poultice, for rust, diatomaceous earth is one of the main ingredients. Ammonium oxalate, oxalic acid and hydrofluoric acid (diluted only) are common rust cleaners or rust cleaner ingredients, but there are many others. The two together should form a paste with a consistency like peanut butter, so add more liquid if it’s too dry or more earth if it’s too soupy.

Be even and spread the mixture fairly thickly, up to 1/2 inch deep. Wait for a day or two; the poultice should be dry when it’s ready to remove. Repeat the process if necessary; you can apply the poultice multiple times, which may be necessary for a difficult stain.

Rust stains on marble can be cleaned using a poultice, which is a paste formed from a mixture of materials. Mix some liquid commercial rust cleaner with some diatomaceous earth. Cover the poultice with a sheet of plastic and tape down the edges to seal it. Scrape off the poultice with the putty knife, rinse with distilled water, then dry with a soft cloth.

Can I Remove Rust Stains From My Marble? by marblemakeover.com

The answer to the “what is the cause” questions changes the nature of the problem and the result. If so, rust stains from an object left on the marble are typically easier to deal with. Of course, you will know that the stain is from an object if it has a very distinct shape and is red-brown in color. Iron deposit rust stains result from flood, plumbing leak, grout cracks or poor installation. The staining will continue to occur as long as the marble is exposed to moisture.

Typically rust spots from such a problem are through the whole stone and look like yellow-brown stains rather than red-brown with a distinct shape. You’re only solution then is to live with the stain or to rip it out, fix the leak or otherwise seal the source of moisture and re-install.

Marble Floor Has Orange Looking Stains by truckmountforums.com

Many white marble tiles contain naturally occurring deposits of iron. If iron is present in the marble tile, it will begin to oxidize when exposed to water or other oxidizers such as acids or household bleach. This oxidation process is accelerated when the tile is saturated as with the flood in the above example. If you expose a brand new nail to water and air it will rust and turn brown.

If any amount of iron is detected, it is possible that iron has entered the stone through the water supply. This is very important if the tile is being cleaned with this water. If iron is present naturally in this stone it will probably be detected in the spare tile.

A moisture meter is a useful instrument that can be employed to check the tile for moisture. Be prepared to repolish the marble since these chemicals can cause etching. Before the above procedure can be performed, it is important that the affected tiles be dry. The above procedure has proven successful in some cases of iron staining. I bet you can use a strong peroxide solution or rust remover to minimize this. I also have used ammonium bi-fluoride solutions to treat rust in the past as well.

It is rust stains that naturally occurs when the iron deposits reacts with water or repeated long term exposure to moisture. You can recommend that your friend pulls the 3-4 tiles out and replace them.

But since it is a natural stone floor there will be differences in color. In the above example with the home builder, the yellowing was a result of oxidation. White marble tiles can remain on a floor for years without yellowing, then over time may slowly turn yellow and in severe cases may turn completely brown.

If a flood has occurred or excessive water was used, first check the water for iron. Check with your local plumbing supply store or store carrying water softening supplies. To eliminate the iron there are chelating chemicals that can be added to the water to prevent the iron from staining. If there are spare tiles that have never been installed also have them tested. If the tile contains moisture, it is very possible that iron is beginning to oxidize. After 24 hours, remove the poultice and rinse the area with water and a chelating agent. If water or moisture are still present, oxidation of iron may continue.

New installations should be sealed with a good quality penetrating sealer (impregnator) which will help prevent oxidation of the iron by eliminating moisture. I bet you can use a strong peroxide solution or rust remover to minimize this. Keep in mind that it can leave severe etches that will require refinishing and polishing. White marble contains iron that rusts with repeated and persistent application of moisture.

Effective Cleaning Of Rust Stained Marble by link.springer.com

The discolouration alters the appearance of the stone, which is undesirable from an aesthetic point of view.

To begin with, solutions of cysteine in combination with sodium dithionite and ammonium carbonate were tested by immersion of samples into the different solutions.

The cleaning results were evaluated by visual observations, cross sections, and etching of the surface by testing on high gloss marble. Although marble is a relatively stable material, the desired white surface is unfortunately prone to tarnishing when used in outdoor environments [1 ]. The solubilized ions are then transported by rain onto the marble surface, resulting in rust formation [4 ]. Rust discolouration of marble is characterized by areas or stains having an orange to brownish colour, which alters the appearance of the stone.

Due to the nature of the discoloration and the possibility of damaging the stone, the stain can only be removed by chemical cleaning. Thioglycolate is presumably the most efficient ligand for cleaning rust stained marble [12 , 13 ]. In this study, we have aimed to investigate and develop a new method for rust cleaning of discoloured marble. Another advantage of this poultice composition was its shrinkage properties: when drying it shrank practically only in the direction of thickness, leaving the area dimension intact. After 24 h the samples were retrieved, rinsed with water and dried. The plastic film was then removed and the sample was left overnight to dry the poultice. These observations indicate the importance of dithionite with respect to both the kinetically reduction and dissolution of rust as well as the prevention of the cysteine oxidation. The difference reflects the water absorption and the capillarity of the marble as well as the coarse porosity type. The right part of the photograph shows the poultice material after cleaning and the yellowing of the poultice material reflects the absorbed iron. The rust layer was removed after one treatment, leaving a cleaned surface without rust stains.

Despite rust staining being a conspicuous phenomenon and numerous works that have dealt with the problem of removing rust stains, a simple and non-toxic method has so far been missing.

This means, from a thermodynamic point of view, that rust can be examined as goethite, and thus the cleaning of rust can be considered as removal of goethite. The current method for rust cleaning involves application of different ligands and reducing agents mixed in a poultice and placed onto the stone surface. The ligands are used either alone or in combination with reducing agents like thiosulfate, dithionite or polythiophene [3 , 10 ]. In addition to this, a slightly violet colour may appear on the marble when cleaning with thioglycolic acid, which demands a second cleaning [12 ]. Laponite produces a colourless thixotropic gel that is easy to apply on specific areas and on vertical surfaces. This resulted in better mechanical properties, increasing both the adherence and the cohesion of the poultice, making it easy to apply and remove in large pieces without crumbling.

Hence a uniform cleaning from the centre to the edge of the poultice was obtained.

The marble plates were used as wall facing and, when dismounted, a heavy iron discolouration was present on the backside of the plates. For cleaning in solution, pieces were further cut into smaller parts at 4 × 2 cm.

All solutions were contained in crystallization beakers and placed on magnetic stirrers, which were stirred slowly for 24 h at ambient temperature.

Based on the results from the solution experiments, iron removal was investigated with the cleaning agents mixed in poultices. The poultice was then removed, the sample rinsed with water and dried in air. The plastic was then removed and the poultice allowed to dry for additional 24 h before removal, where after the surface was finally washed with water. Higher concentrations are observed in internal cracks and bigger pores in the stone. Leaving the solution 2 and 4 exposed to air after retrieving the sample, cystine precipitation was seen after 48 and 24 h, respectively. The faster precipitation in solution 1 and 3, also shows the acceleration of cys oxidation in basic solution. Therefore, this issue was further investigated in the poultice cleaning experiments as well as in an experiment on high gloss polished marble. By comparing the backside of the samples with the treated surfaces, no further etching of the surface could be detected apart from the etching already introduced by the artificial discolouration. The blackish shades still observed after cleaning are likely to be pyrite or other impurities still present in the underlying pores in the stone.

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