Big Ceramic Store Blog

Fixing Cracks In Your Pottery Piece

I just pulled an Easter basket out of a bisque fire, and dang it... there is a crack where the sides meet the base. UGH!!! Question is, do I try a repair, or toss it in the trash?

How many times have you come across a crack in your piece, either in the green, or the bisque stage? I know for me, it's happened a few times.

You spend a lot of time and effort on a piece, set it off to dry, and all of a sudden you find a crack. Or, you open the kiln after a bisque fire, and there is a nice size crack that you didn't see when you put it in there.

Read along as I offer a few tips/tricks I've learned for repairing cracks. I will warn you though, I personally have only had about a 30-40% success rate at repairing cracks. Regardless, sometimes, I just have to try!

You threw a beautiful vessel, let it set up to leather hard, trimmed the foot, and put it on a drying shelf. A week later, you are ready to put it in a bisque fire with your other pots, and you discover a small crack in the bottom.

What to do? Here are a few options.

1. Patch-A-Thatch by Duncan

patch a thatch

  • Scrape out a little clay around the crack
  • Dampen the area with water
  • Apply a generous coat of Patch-A Thatch
  • Allow it to dry
  • Sand, scrape or sponge off the excess
  • Decorate or fire your piece

2. Paper Clay Slurry (Magic Mud)

  • 1/3 cup chopped paper (toilet paper, paper towel etc…)
  • 2/3 cup same body clay as piece to be mended, pulverized
  • Cover with Magic Water and soak 8-12 hours
    • Magic Water Recipe
      • 1 gallon of water
      • 1 ½ teaspoons soda ash
      • 3 tablespoons liquid sodium silicate
  • Put the mix in an electric blender and blend until all lumps are gone
  • Allow it to settle, drain off excess water
  • Scrap a little clay from the cracked area, apply the slurry, allow it to dry, clean up excess and fire away

3. Vinegar and clay scraps

  • Scrape out a little clay around the crack
  • Mix bone dry clay (same clay body as the piece) with some apple cider vinegar and create a slurry... allow it to set up a little while
  • Dampen the crack with apple cider vinegar
  • Apply mixture to the crack (over compensate a bit) and cover it with plastic to allow for a slow dry
  • Once the patch has dried, clean it up by scraping, sanding or sponging off the excess

So, you already bisque fired the piece, now what? Well, it's pretty simple...

  • Patch-A-Thatch or other mending agent like Marx Aztec High Fire Mender
  • Magic Mud
    • Rreplace bone dry clay with pulverized bisque clay of the same clay body and follow the directions outlined above

Like I said before, success isn't guaranteed, but sometime you have to try anyway. Good Luck!

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