Float glass plants work by literally floating a thin sheet of molten glass on top of a giant tank of liquid tin. They have a swimming pool of liquid tin, float molten glass on top, and then push it along the tank length wise.
The glass and tin is then gradually cooled until the glass is solidified. It's then cut into pieces, cooled and stacked.
If the thing suddenly stops, or there is a hiccup of some kind, the thermal expansion of the glass, along with its extreme hardness (lack if strength) it will just shatter the whole mile long sheet of glass. My understanding is that it takes the better part of a year to recover from something like this.
In aluminum, its basically electroplating. They basically electroplate the aluminum out of the ore onto the ingots. My understanding is that takes a few weeks to a month to recover from a similar incident.
Or ceramic cladding for an iron pole, depending.
Either way it's a rebuild, not a restart.
I love that way of describing it.