This problem is usually observed on the bumper surface before printing. Causes and solutions:

Causes of Tampon

If this problem is caused by a very hard pad, a soft pad should be used.
If the worn surface of the bumper is rough and porous, the bumper should be renewed.

Causes of Cliché

If the cliché is prepared with a raster that is not suitable for the image, or without a raster, a raster suitable for the design should be applied.
If the depth of the cliché is too high, a cliché with less depth should be prepared. Or, the pause time of the buffer on the cliché or material should be increased.
If the first exposure time is long during the preparation of the cliché, a new cliché with a shorter first exposure time should be prepared.

Causes of Ink

If the ink is too thin, the amount of thinner should be reduced.
If the ink dries slowly, fast thinner should be used or the waiting time of the pad on the cliché should be increased.

Material-Related Causes

If the material surface is shiny, the surface should be cleaned or ink suitable for the material should be used.

Other Reasons

If the pad pressure is too high, the pressure of the pad on the cliché and the material should be reduced.