  We present new techniques in cooling 39K atoms using laser light close to the
D1 transition. First, a new compressed-MOT configuration is taking advantage of
gray molasses type cooling induced by blue-detuned D1 light. It yields an
optimized density of atoms. Then, we use pure D1 gray molasses to further cool
the atoms to an ultra-low temperature of 6\,$\mu$K. The resulting phase-space
density is $2 \times 10^{-4}$ and will ease future experiments with ultracold
potassium. As an example, we use it to directly load up to $3\times 10^7$ atoms
in a far detuned optical trap, a result that opens the way to the all-optical
production of potassium degenerate gases.
