Blotter Art is a term that refers to the artwork that liquid LSD is traditionally dropped onto to, the artwork perforated into tiny squares then torn down and distributed.
Blotter art was first used in the 1960's before this liquid LSD would be dosed in colored pills similar to ecstasy, but when busted dealers started to be charged based on the overall weight of the pills seized rather than the quantity on LSD present on each pill they quickly found a new lightweight alternative.... in comes Blotter Art.
The lightweight paper was easily soaked and dosed with liquid LSD and allowed dealers to "brand" there sheets and stand out from others.
Since the 1960's the legal hobby of collecting unused (un dosed) blotter art has flourished as the art has grown even more beautiful with many rare / vintage / signed sheets being seen throughout the years.