Humboldt H-3135/37 Humboldt Vicat Tester - Manual (Page 4)

Maintenance
Since the frame has precision bearing surfaces, frequent cleaning of the plunger
to prevent sluggish or sticky movement is recommended. Although dry wiping
of the plunger with a lint free cloth will usually suffice, isopropyl alcohol can be
used if necessary to remove gummy deposits. Do not apply any type of lubricant
to the spindle. The scale face can be cleaned using a soft cloth dampened with
a mild detergent. Use of aromatic solvents could cause damage.