Mortar on wild limestone rocks

Discussion in 'Horn Depot' started by 14tokihorn, Dec 28, 2011.

  1. 14tokihorn

    14tokihorn 1,000+ Posts

    I say wild - what i mean is just limestone rocks collected from the ground.

    Q: how clean does the rocks need to be for a good solid application of mortar?

    One source said: " well, the rocks are probably going to be stained - no matter how much you brush & wash w/ water, so just knock off all the loose stuff, the stains won't matter. "

    How about tri-sodium phoshate (TSP) - since it isn't a detergent ?

    I don't have a pressure washer, and seems like over kill.


    Advice ?
     
  2. jmatt

    jmatt 1,000+ Posts

    Isn't a big point of using limestone is the look you get when it ages? So why mess with it?
     
  3. 14tokihorn

    14tokihorn 1,000+ Posts

    Oh, I'm wanting to use mortar on one surface of the rocks. How clean does the surface need to be so that the mortar bonds / sticks well?
     
  4. Uninformed

    Uninformed 5,000+ Posts


     
  5. Kahuna

    Kahuna 25+ Posts

    The stone doesn't need to be spotless on the contact surfaces for a solid bind. Think of the condition of stone that is delivered for construction. It is dusty and somewhat dirty, and the masons sure don't waste time scrubbing the rocks. If you are using field stone, I would just use my gloved hands to brush off any loose dirt on the contact surfaces before slapping on the mortar. If the dirt is too wet or gummy to brush off, then use a large wet sponge to wash off the contact surfaces. If a little dirt remains in deep pockets, that's no problem. You don't need 100% contact between the stone and mortar for a tight bind.

    I live on Lake Travis with an abundance of limestone on the shoreline that I use. Rather than dirt, the rocks are often covered with a thin layer of moss (wet or dry) from being submerged. It makes such a solid layer that I have to wire brush off the contact surfaces before using. It is a big pain.

    Once you have your project built and the mortar has set for a week, you can use your power washer to clean the dirt off the face of the rocks. The dirt stains will remain, however. If you have a high PSI washer, be sure to start carefully so you don't cause any damage to your project. If the dirt stains really bother you, you might try a test cleaning on a spare rock with some muriatic acid (available at pool supply stores).
     
  6. 14tokihorn

    14tokihorn 1,000+ Posts

    ^
    ^

    Thaks so much, a wire brush will do it - I'm good to go now.
     

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