Depending on the size of the cross-sectional area of the adhesive bond, it is often possible to take two bonded pieces apart successfully. However, several variables will affect how easy or hard it is to do without breaking the glass. Medium viscosity adhesives that have a thicker bonding layer are easier to take apart than an ultra-thin viscosity adhesive that has a very thin bonding layer.
The key to taking bonded pieces apart is bringing the entire bonded assembly to a temperature whereby the adhesive becomes slightly elastic. Usually, this occurs around 150 F. The simplest method is to use a regular oven.
Place your glass assembly in the oven and set the temperature to 150 F. Be sure to place the bonded glass in the oven first, as you need to gradually and evenly heat the piece and avoid cracking glass, which happens when heated too fast.
Let the piece gradually heat up and stay at 150 F for at least 10-15 minutes. Using well-insulated oven gloves, remove the glass from the oven, and with the base held firmly (an assistant is a big help here), apply some sideways pressure to the upright piece. Often this pressure will be enough to release the two parts. If not, take a single edge safety razor blade (as shown above) and push the blade into a corner of the bond joint.
The blade’s sharp edge will often start to split the heat softened adhesive, and as you push the blade further into the joint, the bond will begin to separate. If this does not work, increase the oven temperature to 175 F and try again. It is not an easy process, but it could save and recycle expensive pieces.
The typical scenarios when an awards shop would need to do this:
- When the two pieces are misaligned and look bad after gluing
- When an item has incorrect engraving, and the award shop tries to save the base and glue it to another piece with the correct engraving