There are many ways to achieve the speckled or mottled patinas.
One way is to use sawdust (think coarse, medium or fine) which has
been dampened with the appropriate solution (not soaked).
Also hot patinas can be spritzed on from a distance to the spray
particles/droplets can spread out and form a random pattern. Or a
tooth brush wetted with the patina solution and via bristle brushing
with the tip of one's finger, the drops are released, or via a short
haired paint brush, same technique as the tooth brush. Mottled
patinas can be done with hot patinas by dabbing with a brush (tips
only) or a piece of sea sponge. Piece has to be hot enough to keep
the liquid patina solution from running (also application item must
be "dry" enough. If you want a "ring" of patina and little or no
color in the center of the mottling, use very dilute patina
solutions and hold the brush/sponge in place on the piece for a few
seconds. If you want the whole sponge/brush area to be colored use
more concentrated solutions and do not hold the sponge/brush on the
surface very long (more like just a dab). Piece of rag, piece of
crumpled paper leaves, grass, etc. can all be used for applicators.
Also crushed stone, smooth stone, seeds, plain dirt and most
anything with a "grain" can be used in the "sawdust" method given
There is much more technique/on patination than given
here. This is to get you started.