Checks are best considered as a (visible) sub-set of grids, and each check consists of two assemblies of parallel lines, one superimposed on the other at ninety degrees. In the conventional textile context, one assembly of parallel yarns is superimposed on another at ninety degrees. These parallel lines caused by the yarns remain visually apparent in the finished composition. Commonly, checks are considered simply as a variety of woven textile and Scottish clan tartans, or plaids (common terminology for tartans in the USA), famously display a checked feature, using differently colored yarns in woven-textile form. Often the sequence of colours and the numbers of yarns used is equal in both warp and weft directions. Where this is the case, the tartan may be considered to be ‘balanced’ or ‘regular’, with the component yarns creating square units repeating across and down the fabric. Thus in balanced tartans, lengthways components have identical ordering, colouring and measured width to those used widthways. Meanwhile an unbalanced check lacks one or more of these attributes. This paper explores further the nature of Scottish clan tartans, using data collected from collections of rare tartans held at ULITA – An Archive of International Textiles at the University of Leeds.