Coating defects and adhesion issues will occur during your coating process. Determining the root
cause can sometimes be a daunting task if your technical team is not experienced. In most cases
coating companies experience either a performance or appearance issue. A few common coating
defects are voids, char lines, or a mottled looking appearance. In most cases these appearance
issues can be corrected by checking the manufacturers suggested application for solids and
performing periodic checks throughout the coating run. The coater operator needs to maintain and
check their coat weight and could use a smoothing bar if available. It is also recommended to
corona treat the material to promote better flow and adhesion. Another common defect is foaming;
which can occur in the adhesive drum, tote or coating pan. Foaming can be caused by mixing the
adhesive to quickly, at the wrong angle or blade width. Foaming also could be a by-product of a
contaminated return line or coating pan. Most foaming issues can be resolved by using a defoamer.
If foaming is not controlled it can lead to appearance and adhesion issues such as: voids, skips
and adhesive tackiness. The last common defect that adhesive coaters face deals with application
errors. Adhesive coaters can apply their adhesive using a Slot Die, Mayer Rod, Gravure or Gap

technologies. Each of these applications have their own advantages and disadvantages which can
lead to appearance or adhesion issues. The most ‘ common sign of application cylinder
issues are voids, char-lines and ribbing on the application cylinder. These adhesive
imperfections can lead to performance issues due to inconsistency in the coat weight. Often times
these issues can be corrected by using a new adhesive batch or checking for proper solid content
when mixing.

In summary, it is imperative that your company has an experienced technical team to handle the day
to day issues that arise. It is also equally important to have a thorough training program for all
new operators as well as continued class training to freshen up on all new adhesive technologies,
processes and
equipment. It is impossible to predict when an issue will occur; but we can remain preventive and
have a solid plan of attack when they do.

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