I find it a lot more controllable to use a hot air gun aimed at a chip on a piece of flat tile. You can see what is happening and stop when the chip gets soft. Just press the chip down on the tile with your hand while it cools and it's flat! You need one of the industrial-type guns used to remove paint, etc; a hair dryer won't get hot enough.

You can still damage a chip but less likely as you can pick it up as it heats and stop when it starts to get flexible. After a couple of trys, you can tell when it's hot enough because the chip no longer 'clinks' when you drop it on the tile; it just goes 'thunk' <g>.

DonL