As a rule the lower the grit count the coarser the file and the bigger the actual grit sand is. As a result the file will make deeper scratches that are quite diffi cult to remove. We advise to sculpt with the brush not with the file to prevent service breakdown. The molecular structure of the artificial nail can be jeopardized when too much pressure is applied during the filing process.  The differently colored core indicates the rate of flexibility of the files, the blue core is harder and the file as a result is coarser. The yellow core is more flexible and the file will feel softer.