Usually when an art work enters the permanent collection of a major public museum in Canada and elsewhere, that's the end of the work's story as a marketable commodity. Once in the vaults or on the wall or on the floor of an institution, it's unlikely you're ever going to see the artifact at some future date pictured in an auction catalogue, in the show window of a private dealer in downtown Toronto or above the fireplace at Aunt Joan's log cabin in Canmore.

Still, entering a public collection is not entirely "a lock" on immortality. Galleries and museums, especially ones with long histories, change their orientations, tastes and focus on purpose and by happenstance just like humans: A landscape by an 18th-century French painter that may have been an acceptable donation or good purchase in 1927 may seem an anomaly if the holding institution has since accumulated a substantial number of important paintings by Andy Warhol, Roy Lichtenstein and other Pop masters of the 1960s.

Hence the phenomenon of deaccessioning – the art world's preferred term for what might otherwise be called "the thinning or culling of the herd." You can see deaccessioning in action Wednesday evening at Toronto's Waddington's auction house where eight works are being sold from the Art Gallery of Ontario. The six paintings, one miniature panel and a small marble sculpture are going into the bidding as part of Waddington's fall sale of decorative arts and international fine art with a collective value, by estimate, of $43,000 to $74,000. It's the first time the auction house, founded in 1850, has ever sold an AGO consignment, and it's the first time the 114-year-old gallery has gone the auction route since 2007, when it sold two portraits by Sir Joshua Reynolds through Bonhams London.

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None of the AGO consignments, a "disparate bunch" of European creations, is by an artist with a household name – Théodore Weber anyone? Emilio Fiaschi? – nor is this a case of the AGO looking for a quick windfall: The petite gouache on ivory panel by Carlotta Nowlan (fl. 1885-1911), titled The Blue Ribbon, for example, has an estimate of only $300 to $400, while the priciest offering, an oil called Building Sandcastles by Hague School alumnus Bernardus Johannes Blommers (1845-1914), has its high-end estimate fixed at $50,000. Moreover, their imminent "loss" to the marketplace is unlikely to hobble the AGO in any way since its permanent collection already numbers more than 83,000 artifacts.

Nevertheless, the AGO is taking the deaccessioning seriously, strenuously following guidelines agreed to by the Association of Art Museum Directors and the Canadian Museums Association, among others. (You can read the AGO's policy at ago.net/ago-deaccessioning-policy.) Overseeing this deaccession in particular and deaccessioning overall for the AGO is Lloyd DeWitt, European art curator there since 2011.

While deaccessioning always has gone on at the AGO, "in the past it has been in fits and starts," he said the other day. From here on, "We're committed to making it an ongoing process. … All the departments at the AGO are currently reassessing their holdings and will be deaccessioning next year and in the years to come. Here it's just a case of the European department being the first one out of the gate."

Quotas, he stressed, are not at play. The primary criterion in assessing a work's potential disposability is "whether [it] belongs in our collection or not or whether [it's] better off leaving." The art the AGO has consigned to Waddington's "lacks utility to the gallery," he observed. "Generally, they don't get exhibited at all and that's almost always because there are better examples out there. With the Blommers [which has been at the AGO since 1949], it was thought amongst curators and myself that Blommers doesn't represent the best of the Hague School. Yes, he is very charming and popular with certain collectors, but this one composition exists in several versions so it's not a unique or a very especially important painting." Admittedly, once it's sold, the AGO will no longer have any Blommers in its holdings. But, said DeWitt, it's not a big loss as the gallery has "a very rich group of Hague School objects."

The eight lots originally were part of a slightly larger batch of European works. Before resorting to auction, the AGO prefers to offer its deaccessions to sister institutions across the country as gifts, exchanges or items for sale. Said DeWitt: "The policy is to make every effort to keep these objects in the public realm" and relocate them to relevant galleries "rather than scatter-shot."

The AGO's share of the Waddington's proceeds will be dedicated to new art acquisitions, DeWitt added. Like most not-for-profit public institutions, the AGO depends largely on the kindness of donors to ensure the buoyancy and clout of its permanent collection. Still, it does maintain an annual art acquisitions fund of about $700,000. Any unspent funds in one fiscal year are carried over to the next. In 2011-12 it spent almost $250,000 acquiring art, in 2012-13 $514,000.

Waddington's Toronto auction of decorative arts and international fine art starts at 7 p.m. ET on Dec. 10 (waddingtons.ca).