Does the process of chemically strengthening glass change its volume?

The process of chemically strengthening glass replaces sodium ions in the glass's surface with potassium ions through a process that uses a potassium nitrate bath solution. These potassium ions are larger than the sodium ions and therefore wedge into the gaps and create pressure on the surface of the glass which can make it 6-8 times stronger than glass that is untreated. My question is whether this process would be expected to cause the glass to swell or change volume.


I have conducted experiments with chemically strengthening blown glass globes and have measured a consistent volumetric increase in the diameter of the globes post process. I am trying to determine how to predict and estimate this change. I can't determine if this is the result of the added mass from the potassium ions or if the surface pressures themselves are stretching the material.


I have talked to a few chemical engineers and looked through textbooks and online journals but much of the research done on this topic seems to be proprietary. I am posting my question here in hopes of finding someone who can point me in the right direction with my research.


This is my first question asked in this Stack Exchange Chemistry Site. Please let me know if there is anyway I can improve my question.


