According to George Ridley Scott's book History of Torture Through the Ages - Chapter XVIII, branding was far more commonly used, almost exclusively used, as a form of punishment by torture rather than as a means of obtaining a confession or other witness testimony. The branding iron was used to mark convicted criminals in a fashion that, before extensive paper records and electronic communication, was effective in ensuring that repeat offenders were accurately identified:
Branding
This punishment was at one time widely practised in
England. The irons employed bore marks or letters of
various kinds, for use according to the nature of the offence.
The inside of the left hand was usually chosen as the place
upon which to apply the hot iron. Rogues and vagabonds
were branded with the letter R; thieves with the letter T;
and those guilty of manslaughter with M. The objects of
branding were twofold. There was the punishment
effected by the red-hot metal being impinged, none too
gently, on the skin; and the marking of the criminal so
that if he again be apprehended for some offence or other,
the court would be aware of his previous misdemeanour.
....
In France, for all kinds of minor offences, the punish-
ment was branding with the fleur-de-lis. In Russia this
form of punishment was widely practised in the fifteenth,
sixteenth, seventeenth and eighteenth centuries. In addition, slaves, as a matter of routine, were branded on the
forehead and cheeks.
The implication seems to be that other forms of torture, such as the boot and the rack, were far more effective at obtaining confessions and witness testimony than branding irons.
Torture of the Boot
The torture of the boot was considered by contemporary
observers to be the " most severe and cruel pain in the
world." So dreadful was the sight of a human being suffering this torment that, says Burnet, " when any are to be
struck in the boot, it is done in the presence of the Council,
and upon that occasion almost all offer to run away." For
this reason, an order had to be issued compelling a number
to stay; without such an order the board would have been
forsaken.
This instrument of torture was an iron container made
in the shape of a boot and designed to encase the naked limb
from the foot to the knee. Wedges of wood or metal were
inserted between the flesh and the sides of the apparatus and
driven in with a hammer. The flesh was lacerated and often
the bones were crushed and splintered in a shocking and
dreadful manner, the terrible punishment continuing until
the victim confessed. It was rare for anyone who experi-
enced this torture to be other than a cripple for the rest of his
life.
Holding the Feet to the Fire
Scott goes on to describe a more common use of heat than by branding:
There was, however, a "torture by fire," which constituted one of the three favourite torments employed by the Inquisitions of Italy and Spain, also,
more rarely, by those in other countries, to force their
prisoners to confess. The accused person (the torture was
applied to males and females alike) was fixed in the stocks.
The legs and feet were bared, and the soles well-greased
with lard. A fire was lighted and the feet literally fried
by the heat to which they were exposed. When the prisoner
began to cry out in agony at the intolerable heat, a screen
of wood or metal was placed in front of the fire and a demand for confession made. If this was refused, the screen
was removed and the prisoner again subjected to the frying
process.
Perhaps our society has grown overly squeamish; if the most horrific torture we can conceive of was routinely used in earlier times as both a routine medical procedure to control infection (with no anaesthesia beyond a double shot of brandy) and as a standard penalty for both major and minor felonies; and actively disdained as an ineffective means of torture.
