The frequently unstable [ephemeral, ed.] materials found in many of today's sculptures and installations have required artists, collectors and museum conservators to consider questions surrounding the longevity of these art works. In some cases, artists may specify that materials which will change radically in appearance over time should be allowed to take their course [...for example], Janine Antoni would rather risk changes in appearance than alter the nature of the material [...] In other instances, artists might require all or part of a piece to be remade each time it is displayed [like in the works of Gonzales-Torres, where replacement of material is possible to some extent, ed.]. Ephemerality was intrinsic to the aesthetic of Gonzalez-Torres, whose piles of candy or stacks of printed sheets of paper were meant to gradually disappear and then be reaugmented. But even in such cases, the readily available can quickly become the impossible to obtain, as product lines change or companies cease production. Buskirk, 2000, p. 113 -118