The Duncan Litening is one of the most sought after models from the old Duncan company. Duncan was always trying new painting methods to make their line more diverse, and the Litening was created for crackle paint. One color is painted on the yo-yo first, then a second color is sprayed on top. As the second coat drys, the lines of the first color show thru. They look like bolts of "lightning", so hence the name "Litening". This was a very short lived model from around 1958. The correct effect was difficult to create consistantly, and was discontinued.
Pictured here is a Flat White Litening with thick, Dark Blue lines. A good example of the inconsistancy problems encountered in production, and the wide range of color combinations tried. And the wide variations in the vidth of the crackle line and final finish.