Previous attempts to solve the fog issue
Many attempts have been made over the last several years to resolve the problems associated with the use of rock drill oils, most notably the tendency of most lubricants to generate small aerosol particles commonly referred to as "fog". Chronic exposure to oil fog has been documented to cause respiratory health issues, many of which have been under-reported, according to governmental agencies.
Rock drill greases
By increasing viscosity, some reductions in fog generation were achieved, for example by substituting the recommended grade of rock drill oil for a higher viscosity, or by switching to a liquid grease.
Liquid greases will reduce oil fog, but they tend to separate when exposed to moderate heat, resulting in substances such as overbased calcium sulfonate in one phase, and mineral oil in the other phase. This separation can lead to blockages within the tool, resulting in premature equipment failure.
Viscosity should be carefully matched to the application to ensure that excessive drag is not created by the lube, resulting in hotter running tools, which can lead to tool life deterioration. At the other end of the spectrum, cold weather performance of the higher viscosity lube can result in labored startup, and inadequate initial lubrication, also potentially resulting in reduced tool life. Pneuma-Tool has recently introduced a line of cold temperature lubes which exhibit excellent flow characteristics at temperatures as low as -50C, while providing excellent wear protection for the equipment.
Addition of Tackifiers
Tackifiers have been employed extensively to reduce fog generation, and have worked moderately, at best. The problem with most tackifiers is that they have poor shear stability, which means that they lose their effectiveness rapidly under the high heat and mechanical action produced in many types of pneumatic equipment.