Damaged Marble & Travertine using CLR

webTravertine-Shower-3-650x400We receive many calls from frantic customers after using CLR – Calcium, Lime & Rust Remover damaging Marble & Travertine

CLR from Jelmar is a powerful ACID (see MSDS Sheet HERE) The pH is 2.10-2.30 and Neutral pH is 7.0

This powerful acid will dissolve the top surface of all calcium based stone (marble, onyx & travertine) which has been carefully honed and buffed during the manufacturing process. The grinding, honing and buffing process smoothes the stone and deepens the colors and enhances the color to a brilliant polish.

Acids actually dissolve the finished layer and exposes the raw stone underneath, drastically lightening the color, and also making the surface more coarse to the touch.

To repair this damage, it may be necessary to physically refinish the stone, mimicking the factory process. For very mild etching that you cannot feel a change in the texture, you may be able to re-polish using a polishing paste like HMK P21 Marble Polishing Paste . This paste is very similar to how a polishing compound is used to buff out light scratches on auto paint.

For more severe damage, you likely have to re-hone the surface by using Silicon-Carbide wet/dry sandpaper. Depending on the severity of the damage, you may need to start with an aggressive/course grit. The lower the grit, the more course & aggressive the sandpaper is. To determine which grit to start with, it is best to work backwards until you find the proper grit.

For instance, if you start with 400 grit, you would wet the surface and sandpaper, then sand a small area to see if it is aggressive enough to smooth the surface and make the color deeper. If it does not deepen the color or smooth out the texture then you may need to drop to a more course grit. For very badly damaged stone, you may need to eventually start with 60 grit. The suggested grits to use are 60, 120, 220, 320, 400, and finally 600 grit. The wet/dry sandpaper is usually available in hardware stores, and certainly auto-paint stores.

Technique:

  1. Starting with the lower grit, and using a sanding block, wet both the surface and the sandpaper with water and sand in a circular motion. This should create a white slurry.
  2. Rinse slurry off with water and progress to the next grit. Keep sanding until the color of the stone is consistent, and all scratches are removed from the previous grit.
  3. Once you get to the desired smoothness and color for honed surfaces, you must allow to dry for 12 hours before applying a Sealer or Impregnator. For polished surfaces you will need to polish marble using a polishing paste like HMK P21.
  4. Using a white cotton terry cloth rag, apply P21 Paste to the rag and buff aggressively in circular motion to the stone. The fine abrasive grit in the paste helps to further buff and polish the marble. Keeping enough product on the cloth to keep the marble moist with the paste, buff firmly for several minutes.
  5. Using a separate cloth, buff off remaining paste until marble is free of excess product and it is shiny. Multiple applications may be necessary.

If after restoring the finish and shine of the stone you wish to apply an impregnator, you will have to re-polish the marble (with P21 Polishing Paste) after applying the sealers because the solvents in the impregnator will dissolve the waxes in the polish. Once marble is restored, keeping it clean is simple using a pH neutral maintenance soap like HMK P324 Stone Soap.

For specific advise for your natural stone surfaces, please contact us by EMAIL or phone:

800-380-6881

 

 

About Torin Dixon

StoneCareOnline Expert Blog is managed by Torin Dixon who is an expert in natural stone importing, distribution, fabrication, installation and maintenance of all natural stone surfaces regardless of finish or texture. We are here to assist you in your StoneCare needs.
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