Note #18900 will likely change this behaviour to be exactly the same as any other axes...

With the new Axes.spines shortcut, you can use ax.spines[:].set_color('red') on any Axes without worrying about the names.

I would like to work on this issue

AFAICS there is no clear action:

• we don't want to start advertizing a special ax.spines['outline'] for colorbars if that will change to standard behavior in Enh better colorbar axes #18900.
• ax.spines[:] works on any axis. It's documented on Spines and it doesn't make sense to add documentation on a general feature specifically to colorbars.

@story645 do you see any specific documentation that we should add that would have helped you? Otherwise I propose to close this.

@anushkrishnav Sorry that the action status is not clear/up-to-date.

Haven't closed it because I think it could be useful as a backport only doc (since ax.spines doesn't work on earlier versions) but I don't know quite how far back it'd be backported

I don't think we rebuild old docs...

ax.spines[:] is new in 3.4. https://matplotlib.org/stable/api/spines_api.html?highlight=spines#matplotlib.spines.Spines

We don't update docs for previous releases. So I'm closing this as nothing to do.

@story645 Maybe you want to twitter about this some day? This is not as glorious as subplot_mosaic, but a nice API to share.