Baroness appear to be teasing a forthcoming release with a seeming rundown of the color-coordinated covers for their past efforts on Instagram. Do the Southern sludge metal purveyors have a new album up their sleeves?

So far, they've chronologically displayed the artwork for both their 2007 debut Red Album and its follow-up, Blue Record. As of an hour before this posting, Baroness have posted the cover of 2012 third album, Yellow & Green.

But what does it all mean?

Naturally, fans would expect an upcoming post to show Baroness' next and latest effort, 2015's Purple. But it's the posts' captions that have some intrigued. Each one lists the identifying Pantone number for the particular color.

Indeed, in keeping with the Pantone Matching System, the group have affixed the designations "200 c," "313 c," and "115 c & 576 c," representing red, blue, yellow and green, respectively, as pointed out by MetalSucks.

The Pantone Matching System helps artists, graphic designers and printers pick inks "to ensure that the colors included are achievable and reproducible based on the materials used," the company explains on its website.

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