Tack free to PCM?

A: Many PCM materials have no surface tack at room temperature.
The softer materials will pick up dirt more readily. Softer resins
are more difficult to clean if any dirt is on the surface. If you try
to rub the dirt away, the dirt is easily pushed into the soft phase
change materials. PCM coatings are typically hard at room
temperature rendering them easier to clean off without
embedding dirt.