On page 1, paragraph one, in J. T. Marsh's book An Introduction to Textile Finishing, Marsh states "The term 'finishing' in its widest sense has been held to cover all the processes which fabrics undergo after leaving the loom or knitting machine; from this standpoint, finishing would include bleaching and dyeing, which, indeed, are sometimes regarded as wet-finishing processes." This book was first published in 1947.
In the book Cloth Finishing: Woollen and Worsted by J and J. C. Schofield they state in their preface "The present work has been developed from the author's "Scouring and Milling (1921) which was itself extended into "The Wet Processes of the Wool Industries (1925). This book, published sometime after 1925, runs to nearly 700 pages of detailed information on the wet finishing processes involved in bringing wool, both woollen and worsted, to its finished state.
While the effects of wet finishing can seem magical the processes are well documented and there is nothing mystical about them.
The point is that during wet finishing, processes may be applied that will never be applied again, unlike simple 'washing'. This is why I use the term wet finishing to describe the process of transforming the web cut from the loom into 'real' cloth.
So what do I mean "processes may be applied that will never be applied again."? I am specifically referring to milling or fulling of woollen fabrics. I am referring to brushing to raise a nap. I am referring to a hard press (instead of ironing). Industry may apply other finishes as part of the wet finishing including carbonizing, mercerization, calendering.
These steps, which may be necessary once, are not part of the routine 'washing' of finished cloth.
Another case of choose your expert?
before wet finishing
after wet finishing, including brushing
For more information on wet finishing, Magic in the Water; wet finishing handwovens or the dvd/download from Interweave Press