[alt-photo] Klein Blue (ping Katherine...)

[Keith Gerling]

Painter (and photographer) Yves Klein laid claim to a particularly vibrant
blue that has come to be known as Klein Blue.
http://www.moma.org/collection/browse_results.php?object_id=80103

I haven't researched this heavily, but it seems to be based on Ultramarine.
When I try to make gumprints with Ultramarine they look terrible.  Dingy and
weak.  Do any pigment experts out there have any advice on how one might
achieve a Klein Blue intensity in a Gum Bicrhromate print?