Figure 2 compares the mud viscosity before and after
heating. For the black curve labeled base mud, the test mud
contained water and clay only. For the blue curve labeled
GLG mud before heating, 1 g/L GLG was mixed into base
mud at room temperature, and viscosity was measured (i.e.
without heating). For the red curve labeled GLG mud after
heating, mud containing GLG was first heated to 70 C,
then cooled to 25 C. And mud viscosity was measured at
25 C.