Finally, in comparing the two methods, the DCI is sensitive to surface sampling and the conductivity is volume sensitive. For more than two components in the mix, such as quaternary mixes, the conductivity method can't provide information on the state of mixing of the components other than salt. The DCI can potentially do this if there is sufficient colour difference between the components. However, the DCI is really reflecting a state of mixing at a macro level at the surface of the sample