Investigating 1T-TaS2 with an STM we found that its bulk hexagonal lat
tice bears the inherent tendency to a slow and irregular degradation o
f the surface. The onset of this degradation is triggered by any elect
rical current above a minimum density. This current may be due to the
STM scanning process itself, but degradation can also be achieved by a
current generated by a gross voltage applied externally across the sa
mple. Scan holes, which were observed in accordance with earlier repor
ts, display geometric rather than irregular structures, and their grow
th is considerably accelerated with constant-height scans. Most probab
ly they are formed via abrasion with the tip, which primarily removes
surface atoms at sites with lattice defects or surface steps. Local th
ermal-heating, electrical-field and/or gradient effects do not play an
y significant role in these degradation processes. The ease by which t
he surface atoms are manipulated indicates that the phenomenon of scan
holes also seems to be intimately linked to the metastability of the
1T-TaS2 surface lattice.