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about flint flakes Early
toolmakers would usually start by striking off a first flake to
remove the rough white or brownish exterior (called cortex) from
the core and reveal the dark flint beneath. These first
flakes, called primary flakes, are very common wherever flint
knapping has taken place. Occasionally they are retouched
for use as scrapers, but usually discarded.
After taking off the primary flakes to remove the cortex, the
toolmaker would then start to remove flakes that could be
retouched to make scrapers and other tools (see diagram
below and photos right).
 
He or she did not always bother to remove all the cortex and hence
many flakes and finished tools are found with areas of cortex still in
place. Sometimes, the toolmaker would use the cortex on one
edge of a flake to act as a place to grasp the flake or place the
finger, rather than the sharp exposed flint.
The Mesolithic flake shown right has a prominent ridge down the
exterior or back surface where two previous flakes have been
removed. At the top is the remains of the striking
platform and on the interior surface is the
striking point and positive bulb of percussion.
Retouching
Retouching the edges of a flake is a key diagnostic of an
artefact. However, a flint can sometimes appear to have
been retouched because of edge damage from, for instance, the
plough. Deliberate retouching is often overlapping giving a
scalloped appearance like the cutting edge of a bread knife.
Retouching may have been done either to sharpen an edge, or to
dull it. 'Abrupt retouching' at 45 to 90 degrees was often
done to back-off or dull an otherwise sharp edge to make a flint
easier to hold.
Low angle or invasive retouching was often done with a soft
point such as wood or antler, to sharpen an edge
Ripple marks
Because flint shatters like glass, In many cases there will
also be concentric ripples spreading out from the point of impact, in
the direction of the blow along the surface of the flake scar, like
ripples in a pond. These usually indicate the direction of the blow and
so can be good evidence of human
manufacture.
In fact, the bulb of percussion is the first ripple caused by the impact
of the hammer and hence is much bigger than those that follow.
Removal scars
The scars left on the outside surface of a flake, or both sides of a
biface, are referred to as removal scars.
bulbar scar
It occasionally happens that a small, thin extra flake
will ‘pop’ off the surface just below the positive bulb of
percussion when struck sharply. This can be a useful additional
indication of human manufacture.
It is referred to as an erraileur scar or bulbar scar.
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