Our shower has a has sill about 4" above floor level made from a single piece of marble, approximately 60" x 6" x 1". The shower surround runs down the center, and is well-sealed to it, with no evidence of seepage. However, there is a wide run of soft limestone on the outside which is eroding away, leaving a lengthwise crack in the marble; this has been growing increasingly wide and deep over the past few years.

I'd like to clean it out and fill it with something epoxy-like (ideally black to match the dominant color of the marble), but I'm wary that anything that expands during curing might cause further problems with the stone. Are there any materials that are well-suited to this?

marble sill with crack


2 Answers 2


You can buy powdered marble dust which is used like a mortar to repair cracks.

  • 1
    I see white marble dust on sites catering to sculptors, but haven't seen black yet, other than as a pigment. Assuming I locate black, what would it be mixed with?
    – TomG
    May 2, 2014 at 2:16
  • I'm guessing epoxy, but that's only a guess. Superglue might work but might require a more specialized technique... Either way, you might want to consider practicing on a scrap or a tile before risking it on the real piece.
    – keshlam
    Jan 24, 2017 at 4:45

I would use a knife grade epoxy, activator and black dye. Probably have to order these online since stores hardly carry these things. After you are done just give it a light sanding with angle grinder and diamond flap disc.

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