P: Change background to Library swatch color

We are shooting hundreds of product and model photos. The client wants all of the backgrounds to be a sepcific color that we have in our swatch library. It would be very useful to mask the background in Lightroom and replace it with the color swatch from our CC library.

I think the notion of (say) background replacement to a known flat colour cuts across a designed-in distinction of (for example) Lightroom vs editors such as Photoshop. The former class of software is, at root, there to adjust whatever is already there - with its content variations respected - while the latter class is there to alter (which includes not only adjustment of content, but also outright change of content).

Absent a fixed studio setup, one thought: a local adjustment's Tone sliders could be set to deliberately "blow out" AI selected background extent fully to white, more or less regardless of incidental differences of exposure. And then within the scope of this same local adjustment whatever Tone Curve tonal and hue changes are needed to adjust that full white specifically, back down to the desired tone and hue, could be worked out with reference to the RGB readout. Would be some work, but only having to be done once.

Then the Mask that does all of this could be portable from image to image, and when applied would force a consistent background result regardless of their varying as-shot exposures and WBs. Within reason; and those aspects would still need attention so far as how the subject aside from the background, is being represented. Also not to forget: each photo then requiring an update of the AI background selection, in respect of its particular subject / background.

Set the color swatch you need as reference, so you can get the actual RGB values.

Via Masking select the Background.

Then use LocalHue or Point Color to precisely define and achieve the desired color,

If, as you say, the background is already near the desired color then Point Color will efficiently allow to achieve the color you need (which most likely will be already within range)

Use the RGB values to be sure you have a 100% match or close match.

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