Benzyl alcohol is also commonly used as the vehicle (solvent) by some ink manufacturers.Chelated dyes (introduced commercially around 1953) are stable to light.These pens contain a pressurized feed system instead of gravity flow.
In the liquid carbon inks shellac and borax are used in place of animal glue and a wetting agent is added to aid in the mixing of the shellac and carbon.
When dating tags are detected, it is possible to determine the actual year or years when the ink was manufactured.
Dating tags are unique chemicals that have been added to ball-point inks by some ink companies as a way to determine the year the ink was made.
In cases where known dated writings are not available for comparison with questioned inks, accelerated aging (heating the ink to induce aging of the ink) can sometimes be used to estimate the age of ink using any or all of the above described techniques.
Iron-based inks can be dated by measuring the migration of iron along the fibers of the paper by Scanning auger microscopy.