What is the origin of the word "wash" to mean a net gain of zero?

"Wash"

A situation in which gains and losses balance each other

This appears to be informal North American usage. What is the origin of this use of "wash" to mean a net gain of zero?

Solution 1:

In the UK, an auction item that sells without making a profit or a loss is often said to have "washed its face". This has become more noticeable with the popularity of TV shows such as Bargain Hunt, and Antiques Road Trip.

I have traced this usage back to the 1930s via Google books.

In "Drama: The Quarterly Review", apparently from 1946, I found this:

Which brings us to Glasgow - the real surprise packet. In the dark days of 1941, John Stewart had the pluck to establish his tiny (106 capacity) Park Theatre. With a club subscription to help it washed its face in two years, specialising in first Scottish performances and taking a new play...

Another reference in 1949 in "Civic Entertainment" reads:

When we went into this it was with a very rough estimate and we hoped to make good not by a large profit but being happy that we made ends meet, and the whole project "having washed its face."

However, in 1938 the phrase "washed its own face" was used in the House of Commons (UK Parliament), and documented in Hansard, the official journal of the parliament

The fishing season in the south-east of Scotland of which I am speaking is divided into three parts. The first starts about the first week in May, and that as a rule is very poor as far as earnings go. The second month is rather better, and the third month is, as a rule, good. A suggestion has been made that for the first month's voyage there should be an allowance made by the Unemployment Assistance Board to make up the deficiency between the unemployment scale and wages. During the second period it is calculated that the industry can, as it were, wash its own face, and it is suggested that during the third month the earnings should be reimbursed to the board after the needs of the men have been considered.

The "as it were" suggests that this was considered idiomatic usage at the time, referring to a business being sufficiently mature to be able to operate largely unsupported, and to cover its own costs.

My deduction from this, and other non-financial uses of the term, is that the maturity of the business is comparable with that of a child who is old enough to wash his or her own face, and starts to become less dependant on parental care.