When polishing glass with an automatic grinder, one of the most challenging aspects is overcoming surface tension: that moment when the slurry mix and the water on the metal disc become literally “glued” to the glass sculpture and refuse to detach from each other. It is a tense moment because applying force to separate both surfaces can result in scratches or breaking the glass sculpture.
3 methods to overcome surface tension
If you’re struggling with surface tension during the polishing process, you can try these three methods to overcome it:
1. Using an air compressor
This is the primary recommended technique to overcome surface tension: utilizing an air compressor to introduce air beneath the glass surface.
Begin by vacuuming the disc to remove all water. Then, position the air gun on one side of the sculpture and attempt to blow air under the piece. Theoretically, the air will cause the water to spread, facilitating detachment of the piece. However, it is not always straightforward, as the piece may shift slightly when trying to move it, leading to the buildup of tension once again. You must detach the piece without moving its base or you’ll risk becoming trapped in a loop of attempting to detach it several times.
2. Using your hands skillfully
If the air compressor technique fails, you can also attempt to detach the piece manually. This method is somewhat risky and requires a calm attitude. Skill is more important than strength in this approach. First, extract all water from the disc. Once the disc is dry and the piece is centered, place a towel on the plate between the sculpture and yourself (to protect the piece in case of any mishap during detachment). Then, carefully pull the piece toward yourself to detach it from the disc. It is crucial to remain completely still while doing this and avoid applying too much force. Detachment may take anywhere from fifteen to thirty seconds, sometimes even longer, but it usually proves effective. Exercise extreme caution and patience during this process.
3. Pulley lifting
If the techniques above prove unsuccessful and you happen to have access to a pulley, you can attempt this final method.
In the video, the surface tension is so strong that it temporarily lifts the 40kg disc along with the sculpture. It takes a few seconds for the tension to dissipate and for the disc to finally detach.