James, first of all, Zinc white is not as opaque as Titanium white. Unfortunately it looks to be a fresh tube, but I would highly recomend switching to titanium, it will yield better results.
Secondly, and possibly more importantly, you should be undercoating areas like this before you paint with oils. I would recommend a good, flat primer coat, then use a quality acrylic paint as an base coat. I primer with Valejo and also use them as an undercoat. I apply a base coat of acrylics in what I would describe as a medium tone of the oil color going over it. One thing to remember with oils is, you are painting a VERY thin layer of paint!!!!! Despite the opacity of some colors, it is going on the figure in very thin, translucent layers. That is why the undercoating process is so important for me. Some folks don't use acrylic undercoating, but I found it to be absolutely necessary for my painting style. Much of what you see in the final result is the color of the undercoating doing the work.
Lastly, what you will find with a good acrylic undercoat, is that despite the oils being transparent, you will cover much better with less paint. I don't thin my oils AT ALL when painitng. Some people "leach-out" the carrier from thier paints before painting (place the oils on a thick card stock paper or paper plate and you will see the carrier suck out into the surrounding paper), this provides a more matte finish most of the time (blues being the exception). Remember that with the oils, a little bit goes a long way. Mix all of your shades before hand, shadows, mids and highlights. Then apply them each in steps. I start with shadow tones in the crevaces and along boundries. I then mix in my mids and finish with the highlights on the tops. I hardly use any paint at all when it comes down to it. One other thing to keep in mind is that I have been known to go back in and re-paint some areas a second time if the coverage is not what I wanted. Don't be afraid to let your first round of paint dry for several days, save your palette in the freezer (it will keep for several days there) and go back and work right over the top of your last pass to gain opacity where needed!
Practice, practice, practice! Don't be afraid to make mistakes, I'm the master of them! HTH,
Jay H.
OKC
