After developing the film, he created three separate negatives and exposed one of the three to a red filter, one to a green filter, and the last to a blue filter. Porter then created three matrices by shining a light through each negative onto its own sheet of matrix film. To make the print, Porter then placed the one with the red filter in the blue dye, the one with the green filter in the red dye, and the blue filter in the yellow dye. Dye uptake depended on the thickness of the paper where the thicker paper picked up the most dye. After four minutes and with the dye fully transferred, he carefully lifted the matrix, washed it, and carefully rolled the next matrix in place. He was able to change the hue and contrast of different prints by changing the acidity of the dyes and then repeating the soaking and rewinding process on or more matrices. Once finished, he would create a color image