Compared to ordinary papers, YUPO is sensitive to plate smearing and has a tendency to be affected by dirt.

• YUPO is a non-absorbent material and does not absorb dampening water. (This applies to most YUPO products such as FGS, FRB [G], and FEB [G])
• Many grades except FRB (G) and FEB (G) tend to have lower ink receptivity than coated paper.
• YUPO ink and UV inks tend to emulsify easily. Plate smearing tends to occur particularly with crimson, reddish colors, and light-resistant crimson, thus requiring rigorous control of dampening water.

For this reason, problems such as plate smearing due to condition adjustment or printing, and sudden plate smearing during restart after stoppage are often encountered.
The main causes are:

• Excessive ink (excessive print density requirements)
• Oversupply of dampening water

The cause will be one of the above or a compounding effect. (It is assumed that there is no misalignment of the feed roller or grazing, and that the roller surface is properly managed)

(1) When dirt is caused by condition adjustment or printing

<Cause> The ink is excessively emulsified because the initial supply of dampening water was too large. As a result, the ink pigment eluted in the dampening water and caused "scumming" in the non-image area.

(2) When dirt suddenly occurs when restarting after stoppage

<Cause> Since both the ink supply and the dampening water supply were excessive yet balanced, printing could be normally performed during continuous printing. However, the balance was lost when the printing was stopped, and the ink was excessively applied to the plate surface, resulting in smearing.