Bronzing is an image defect that occurs with some inkjet printers and some papers. Earlier pigment inksets were the most well known culprits - the Epson 2000P was notorious, and the original Ultrachrome inkset had bronzing problems on gloss and semi-gloss papers. The new Ultrachrome K3 printers have pretty much eliminated bronzing as a problem

Bronzing is a phenomenon where, when paper is viewed from an angle, part of the image seems to disappear or taking on a uniform tone in appearance. It occurs because of some of the ink laid on the paper is not properly absorbed into the coating, instead sitting on top of the page. The effect is only visible from an angle and is generally not a real problem in practical contexts, however when visible it is quite unattractive.

In general, spraying your prints with a high quality coating will substantially reduce or even eliminate bronzing with typical semi-gloss and gloss papers.

With super high gloss papers (i.e plastic based papers like Pictorico High Gloss White Film), the spray does work but will leave a visible semi-gloss texture on the print and it isn't an ideal solution. The best option is to try another paper but the problem is inherent in current coating on high gloss papers and there is no perfect solution at this stage.