First, I'd like to thank all the helpful folks that contribute to this forum. I am a self-taught printer making the best of minimal equipment, and your help has been invaluable.
I'm having a weird problem printing duotones. I print the black first, then the spot (different pantone mixes). The problem is that the spot color prints with uneven density. It has strange horizontal (as in, perpendicular to the printing direction) bands where the spot color is less dense or completely absent from the printed halftone. The location and intensity of the banding varies from sheet to sheet. At first I thought the problem might be that I was using an oil based black ink followed by rubber based pantone mixes, so I switched to oil based spots and the problem didn't go away.
I'm working with a one color Hamada duplicator press, laser plates, and zipset inks, alcohol fount solution with a glycerin based additive (anchor ARS-X) to help with scumming problems. I usually let the black dry for a day or two before printing the spot color. I have absolutely no problem printing 4-color stuff, which is why this is so perplexing. I'd like to know if anybody has any ideas about what would cause this, and how to prevent it? When I pull a print of the spot plate on a new, white sheet, it looks perfect, so I know its something to do with the interaction of the black and the spot. I suppose my next step is to try laying the color down before the black, but I don't know if the black will have the same banding problem (which would look way worse).
I've attached a scan representative of the problem.
Thanks
I'm having a weird problem printing duotones. I print the black first, then the spot (different pantone mixes). The problem is that the spot color prints with uneven density. It has strange horizontal (as in, perpendicular to the printing direction) bands where the spot color is less dense or completely absent from the printed halftone. The location and intensity of the banding varies from sheet to sheet. At first I thought the problem might be that I was using an oil based black ink followed by rubber based pantone mixes, so I switched to oil based spots and the problem didn't go away.
I'm working with a one color Hamada duplicator press, laser plates, and zipset inks, alcohol fount solution with a glycerin based additive (anchor ARS-X) to help with scumming problems. I usually let the black dry for a day or two before printing the spot color. I have absolutely no problem printing 4-color stuff, which is why this is so perplexing. I'd like to know if anybody has any ideas about what would cause this, and how to prevent it? When I pull a print of the spot plate on a new, white sheet, it looks perfect, so I know its something to do with the interaction of the black and the spot. I suppose my next step is to try laying the color down before the black, but I don't know if the black will have the same banding problem (which would look way worse).
I've attached a scan representative of the problem.
Thanks
