The first step in removing old adhesive is to determine what type of adhesive it is; epoxy, Super glue (Cyanoacrylate), silicon, contact cement or water base glue.
There are four methods to remove the old adhesive used based on:
A) The type of glue
B) Is the material the glue is applied to porous or non-porous *
C) What instrumentation is available to you
* Non-porous material examples are: Porcelain, china, stoneware, metal. Porous material examples are: Earthware, stone, plaster, wood
Removal Methods:
1) Solvent
2) Boiling water
3) Torch
4) Mechanical separation by cutting the mended connection (used very rarely - creates other issues)
5) Kiln firing (reserved for professional potters only)
Video: How to Remove Old Adhesive Using a Torch?
Wear eye protection, a mask and operate in a ventilated room!!
1) Using Solvent One-part cements, such as Contact Cement or Super Glue (Cyanoacrylate), are dissolvable.
Using a sharp object, poke the old adhesive. If it is flexible, it is most likely not Epoxy and may be dissolved
Steps:
1) In a ventilated room and wearing a mask, saturate the cemented areas with Acetone and wait for several minutes or until you sense softening.
2) If the cemented parts do not separate, apply some pressure to separate them
3) Scrape off the softened adhesive and clean surfaces with alcohol
Warning: Before applying the Acetone make sure you do a small test on your object to verify that the Acetone will not ruin your item. Acetone will instantly damage any polymer based product (paint, varnish, plastic). Apply all the safety instructions for using Acetone including ventilation, gloves, mask and eye protection.
Possible side effect: The dissolved adhesive may absorb and stain porous surfaces.
2) Using Boiling Water Most adhesives will soften up after they are immersed in boiling water.
DO NOT use with stone or plaster objects!!
Steps:
1) When heating the ceramic in water, do not drop the item in boiling water to avoid cracks due to thermal shock. Place the ceramic object in room temperature water and start the heating with the object in the water.
2) After it is boiling for 2-3 minute, inspect the object to see if the cemented parts are separated or can be separated with light pressure. If yes, use heat mitts to hold the hot item and with a razor blade, while hot, remove the remaining epoxy.
3) Grinding with a metal brush may be required if some epoxy still remains
4) Clean surfaces with alcohol
Possible side effect: The dissolved adhesive may absorb and stain porous surfaces.
Electric water heater
3) Using a Torch - the most common way used in our studio This method requires experience with using a torch and how to apply the flame on the surface without causing damage. See video above.
Steps:
1) Heat the cemented areas with a continuous movement and with the flame not too close to surface
2) The heated areas need to build temperature uniformly
3) Apply pressure to separate the bonded segments
4) Once separated, grind or use metal brush to remove the adhesive
5) Clean surfaces with alcohol
Possible side effect: Heat builds up in one area can cause cracking.
Warning: Use in a ventilated area with eye protection
Blazer GB4001 Stingray Butane Torch
4) Mechanical Separation - Cutting The Mended Connection This method is rarely used and is reserved for cases where solvent or heating can damage the mended material (e.g., plaster).
This worst case scenario occurs when the old adhesive, epoxy in particular, was used on porous and soft materials soaked into the porous surface.
Steps:
1) Use a Dremel cutting disc (diamond disc and under running water for ceramic) to cut through the mended line.
2) Once separated, grind or use metal brush to remove the adhesive
3) Clean surfaces with alcohol
Possible side effect: Cutting removes the adhesives but it also removes some of vessel's material which effects the broken pieces' fit requiring more fill, more sanding, more painting, thus, more complex repair.
Warning: This method is recommended only for experienced professionals.Use in a ventilated area and with eye protection
