The Slip Force depends on the mechanics of a much older, forgotten color change, which used the slip mechanism to cause one card to change openly into another. This appeared in the unpublished MSS III, 18, also called “the Asti Manuscript”, c. 1700, p. 51 of the Pieper translation. The manuscript was translated in Gibecière, Vol. 8 No. 1, Winter 2013, p. 29-234. The same application later hit the printed page in Edme-Gilles Guyot's Nouvelles Récréations Physiques et Mathématiques, 1769, p. 33 of the unpublished Hugard translation.
The force application appears to be a twentieth-century creation. It appeared in Ellis Stanyon's Magic, Vol. 13 No. 3, Dec. 1912, p. 20. As was often the case with Stanyon, he didn't cite a source for the sleight. One month later on the other side of the Atlantic, Val Evans claimed credit for the move in The Sphinx, Vol. 11 No. 11, Jan. 1913, p. 221. Victor Farelli, in Farelli's Card Magic - Part Two, 1933, p. 64, shared his belief that Nate Leipzig is to thank for the move's creation.
A modern handling commonly attributed to Gary Kurtz, due to its appearance in Unexplainable Acts, 1990, p. 26, has the same mechanics developed and published by Marc Delahousse in M-U-M, Vol. 67 No. 8, Jan. 1978, p. 34.