Methyl alcohol
This is quite volatile, has a low flash point, and has a degree of toxicity. Ethyl alcohol is also volatile and has a low flash point, but unless iingested is relatively non-toxic. Some halogen-based fluids are marketed as low temperature bath fluids, but these also have a high volatility, may be slightly toxic, and are quite expensive.

Isopropyl alcohol
This is less toxic than methyl alcohol and somewhat less volatile. However, it becomes highly viscous at low temperatures and is therefore unsuitable for use at very low temperatures.

Silicone fluid
It is available in a number of viscosities and can be used over a wide range of temperatures if the proper selection of viscosity is made for the temperature range of interest. A bath containing silicones requires extra care when used for capillary viscometry. If silicones enter inside a viscometer, its calibration factor may be altered by a significant amount. Silicones are also relatively expensive liquids.

Water
This is almost the ideal fluid in the temperature range for which it is suitable. Because in some cases there is a tendency for algae formation, some degree of water treatment may be necessary. Water can be used at temperatures close to the boiling point, but water replenishment to offset evaporation becomes a nuisance and the hot vapor can make working above the bath uncomfortable. Also, it may be difficult to establish optimum control at elevated temperatures because of the rapid cooling resulting from surface evaporation.

Refined white oil (paraffin oil)
Relatively low viscosity one can be used at temperatures above the level at which water becomes unsatisfactory. Because these oils will turn faintly yellow and continue to darken with prolonged exposure to heat, we recommend using an oil with an oxidation inhibitor to retard discoloration. Even with the addition of an inhibitor, after several months, the oil will still darken and must be replaced with new oil.

The search for more suitable kinematic viscosity bath liquid is unending. Hydrogenated vegetable oil, coconut oil, synthetic oil and certain chemical compounds have been used with some success at various temperatures.