Editing Guide to Assembling Models (section)

=== Removing Mould Lines ===
'''Mould Lines''' are small, thin, raised lines which run across the surface of a model.  They can be clearly identified by looking for a continuous running line which does not match up with other model details.  They occur when the two halves of the mould aren't perfectly aligned before casting.  Mold lines are to be removed via scraping with a hobby knife, sandpaper, or files.  All three are viable options, and your choice of tool come down to preference.  What your desired result should be is anything you do not want on the final model not being present, as the painting process will make mould lines very visible, ruining otherwise perfect work.