Introduction: How to Repair Stone Sculpture Broken in a Narrow Area Requiring Metal Insertion (Marble, Soapstone, Alabaster, Granite, Sandstone, Limestone)

By Lakeside Pottery Studio
About: Lakeside Pottery, a nationally recognized Ceramic and Sculpture Repair and Restoration studio, established in 2001 as a ceramic art and pottery teaching facility. We are also craft Kintsugi / Kintsukuroi Japan…

This tutorial is an example of how Lakeside Pottery Studio repairs and restores indoor stone / marble sculptures with heavy load bearing and narrow cross-section breakage needing greater reinforcement.

In this example, the marble sculpture broke by the very narrow ankles with about 60 lbs of load-bearing. Cementing-only would not have been sufficient and insertion of metal rods was required to ensure proper mechanical integrity. Drilling accurately on both sides of the broken pieces for proper alignment is tricky and this lesson illustrates one of the methods we use. For more tutorials, visit our repair and restoration web lessons


Supplies

  • PC-Clear 5 minutes epoxy
  • 91% alcohol
  • Holding container with resin / PVC pellets or similar
  • Epoxy mixing stick or a pin-tool
  • Metal rod (brass or stainless steal)
  • Cotton rag
  • Masonry drill bits
  • Hand drill
  • PC-11 Epoxy filler
  • Air compressor

Where to get supplies

Step 1: Cutting Metal Rod

  1. Cut rod to size - 5" in this case
  2. Grid off sharp edges on the cut rod


Step 2: Drilling Side A

  1. Use masonry drill bit to drill a hole in the center of one side (A) of each leg
  2. Verify fit before cementing rod to side A
  3. Clean the drilled holes with air gun


Step 3: Cementing Side A

  1. Use two-part epoxy (PC-Clear). In this example we use 4-5 minutes epoxy with about 2 minute workable time. Mix well
  2. Fill 2/3 of drilled cavity with the mixed epoxy
  3. Insert rod and turn a few times to ensure that epoxy touches all surfaces
  4. Quickly wipe off excess epoxy with a rag and 91% alcohol


Step 4: Marking Side B Drilling Guide Pencil Line

  1. Mirror the rod orientation on the stone exterior wall to be used as a guide to drill side B correctly
  2. Use pencil to mark the rods location on Side A


Step 5: Marking Side B Accurate Drilling Location

Drilling accurately on both sides of the broken pieces for proper alignment is tricky. There are more than one way to achieve accuracy the shown method is the option we chose for this project.

  1. Insert soft clay in side A drilled hole
  2. Flatten the clay as shown
  3. Use acrylic paint to generously mark the clays center


Step 6: Transferring Side a Hole Location to Side B

  1. Carefully place side B in place
  2. Verify that the acrylic paint transferred from side A to side B
  3. Before removing, continue the previously marked line to side B in the same projection


Step 7: Drilling Side B

  1. Drill a hole using the marked line as a guide
  2. Start with a narrower masonry drill bit (3/16") for better control and accuracy
  3. Drill with the next size (1/4")
  4. Finish with a size larger than side A drilled hole (5/16")


Step 8: Verify Proper Fit

  1. After cleaning the drilled holes, verify fitting accuracy
  2. Use touch to sense continuity at the points of contact


Step 9: Cementing Preparation

  • Clean the drilled holes with air gun
  • Use two-part epoxy (PC-Clear). In this example we use 4-5 minutes epoxy with about 2 minute workable time. Mix well

The shown epoxy has about two minutes workable time.

Use slow cure epoxy if uncomfortable with 2 minutes


Step 10: Applying the Epoxy to Both Sides

  1. Apply epoxy to rods
  2. Fill 2/3 of drilled hole with the mix epoxy
  3. Apply epoxy to all surface carefully of side A and side B


Step 11: Placement

  1. Place the statue two part together
  2. Do not wipe excess epoxy off to avoid smearing. Remove epoxy after the epoxy is set. It will be harder to remove if excess epoxy is removed when it is totally cured


Step 12: Filling Mended Joints

  1. Mix filler epoxy (PC-11)
  2. Apply filler to joint cracks
  3. Sand off epoxy filler when it is cured (24 hours in a room temperature of 70 or warmer)


Step 13: Sanding

  1. Sand filler starting with 220 grit sandpaper, continue with 400 grit and finish with 2400 micromesh silicon backing abrasive
  2. Clean with 91% alcohol prior to painting / glazing

Step 14: Concealing Repair Lines

Visit for painting and glazing steps



Step 15: Video of This Lessons

This video tutorial was put together as an example showing how Lakeside Pottery Studio (https://lakesidepottery.com/) generally repair and restore indoors stone / marble sculptures that require metal reinforcement.