Analysis of Breaks during Fire Polishing

The analysis of breaks in fire polishing can be difficult.  The temperature and heat work are minimal, so the edges can look sharp, which would indicate that the break occurred on the cool down.

But this is where you really need to feel the edges.  If they feel very sharp, then you can be more confident that the break occurred on the cool.  But if there is even the slightest smoothness to the edge as you feel it, the break probably occurred on the heat up to fire polish.

In this picture, there appears to be an annealing break, because of the hooked ends of the break.  That is typical of a break due to inadequate annealing.  It is important to know when the break occurred, so that appropriate remedial action can be taken for future firings of similar pieces.

To determine if the annealing break occurred because the initial anneal was inadequate, it is important to do a touch test. Just looking at it will not be enough.

If the edges were even slightly smoothed, the anneal break occurred on the way up.  This would mean that the anneal of the original blank was not adequate, assuming a reasonable rate of advance was used for the thickness of the piece.

If the edges are razor sharp, the break occurred on the way down, indicating that the anneal after the fire polish was not adequate.  This would mean that in future the annealing needs to be done more carefully on fire polished pieces.

Being too quick to apply a diagnosis of a break during a fire polish can lead to the wrong conclusion, and so the incorrect alteration of future schedules.