Lets take a few and talk about what’s happening… although you probably know, just to be on the same page.
Glass has virtually no thermal expandability and the heat transfer is very low to the surround glass. When you heat a small area, it tends to absorb the heat and expand a slight amount, then breaks from the surrounding glass. These breaks aren’t necessarily or always what you’d call a clean break.
A friend is a glass artisan. He advised me to use steel wool on the engraving after it’s done and not gently. If a shard of this gets into a customers (or your) finger, it’s next to impossible for a doctor to find and remove. I have some steel wool that I’ve used on many pieces of glass work that have never scratched the glass.
How TiO2 and LBT100 (and Cermark) actually work … the coating is heated by the spot, the coating becomes hot enough to form a molecular bond with the glass. I have used LBT100 for a number of years… I get mine fro Amazon, but it’s about $80 for 12oz spray bottle.
The coating can be thick, where you loose detail and require more power, most of these recommend a very thin coating. Higher resolution, less power. Coating thickness is a real bear and you will have to experiment with different types of applicators to see what works best for you. If it’s a spray can, it’s pretty simple but care is required as it’s easy to overcoat these and have poor results.
Many of these products work well on porcelain tile which seems to be a different type of glass. I have quit using them on some types of glassware as the setting are very critical. If you get it hot enough to bond, it may heat the glass enough to break, which is what you’re experiencing. Simply too much heat.
I’m sure you can do this with TiO2, but I didn’t have the patience to detail the settings and it varies by glass type. This link has a lot of ways to mix TiO2.
There is molylube, don’t get taken by this, it produces sulfur dioxide that then combines with water and oxygen to produce sulfuric acid. This is why the laser coating are so expensive… they are safe for you and your machine.
You might try tracing the graphic, then using a fill instead of an image with stucki.
You need to figure out your spot size, as the proper interval is related to spot size.
Good luck
