Wet solution coating – Paul Wu's Blog

Hydraulic Pressure Gauges

There are two types of pressure gauges for hydraulic applications:

Liquid Surface Tension Measurement by Pendant Drop Method

In the coating applications, liquid surface tension measurement is critical, which include liquid-air interfacial tension and liquid-substrate (solid) interfacial tension. Contact angle measurement is a common method for the surface tension measurement; however liquid surface tension might not be available for the measurement. Pendant drop method is a good for this purpose.

Formation of Bénard cells

There is a drying pattern called “Bernard cell”, which is particularly easy to present in solvent borne solution drying.

Gloss measurement-ASTM D 523

Gloss is a measure of object’s surface property, e.g. shiny, metallic, or matte. It measures the percentage of spectral reflection.

Ellipsometry

Ellipsometry is a powerful tool in thin film field to characterize film properties, e.g. refractive index (n), extinction coefficiency (k), surface roughness, crystallinity, etc.

Corona treatment

In the coating/printing industry, the corona treatment is a commonly adopted step to enhance the surface energy of the coating/printing web, typically made of plastics, paper, fabrics with low surface energy of low 30s mN/m or dyne/cm.

Major coating method and thickness control

The following are simple introduction of major coating methods and factors affecting coating process and coating thickness.

Wet film thickness estimation in blade coating or similar process

As a rule of thumb, the wet thickness of a coating is estimated to be half of the gap between blade edge and substate surface in the blade coating or similar coating process.

Coating Defects Inspection Resolution

Surface defects inspection is an important step to in-line detect coating defects such as voids, streaks, clumps, bubbles, scratches etc. in continuous web coating and similar processes. It provides evidences for process optimization, root cause analysis, as well as quality control/assurance.

Category: Wet solution coating