In 2003 his mentor, friend and agent advised him to establish a niche, which he did by creating pieces that are unique in the art world. The key was his choice of material. 

Roofing tin is an interesting surface to paint on, and the technique Giltner developed took full advantage of its rustic charm. By allowing the dark, rusty tin to remain in the richest shadows, he let the image reveal itself in the highlights. He used only white paint with minimal strokes for the gray tones and heavier ones to capture the brightest light. This required a high degree of mastery, as there is no room for error when working with negative space. At the time, Giltner was using scrap house paint for economy, but he later transitioned to acrylic.