The entire length of the viscometer must be maintained at the appropriate temperature. The type of circulator used, the age of the bath fluid, and the bath fluid viscosity will impact temperature uniformity. The circulator and the viscosity of the KV bath fluid need to be balanced to provide a uniform temperature throughout the bath. Change the bath fluid as soon as it begins to discolor, as discoloration usually indicates the fluid has oxidized and the viscosity has increased. The KV bath should not be located near a draft or in a fume hood, which can cause excessive temperature gradients in the bath.
Lawler Model 86-20 http://www.lawlercorp.com/d445_high.html for high temperatures and the Model 70 Series (74, 77, 78, 79) http://www.lawlercorp.com/D445_1_UK.htm kinematic viscosity baths are designed with strong bath agitation and in enclosed cabinets to reduce the effect of room drafts.
