When creating gradients in your artwork, we highly suggest creating those gradients in Photoshop, and not in Illustrator. the reason being, is that Illustrator is a vector based program and doesn’t raster the gradient the same way Photoshop does, and it will create “Steps” in the gradient that look like lines in the final print. The only way to cure this is to create the gradients in Photoshop and then either import the gradient into illustrator, or just completely design the artwork within Photoshop. Please see the attached photos, you can see how much smoother the gradient is in the Photoshop image vs the Illustrator image.
|AI Created Gradient||PS Created Gradient|