I have a project where I designed the front panel from PCB material, and played a bit with solder mask, tinned areas (HASL), and exposed bare PCB material to mimic the look of a vintage computer’s control panel. I am quite happy with the way it looks, with one exception:
The areas to the left and right of the main keypad were originally made from whitish, translucent plastic (acrylic?). I try to approximate this look with the exposed bare PCB material. But the FR4 boards I have received from various suppliers so far are all distinctly yellow — which does not look right, and in fact looks a bit unhealthy.  

Is anybody aware of flavors of FR-4 (copper-clad, for use in PCB production) which are essentially white? Any recommendations for PCB houses which can supply and work with such material?
Thanks!