Re: "sweating it in"
The wood has cosmo laying on it from the inital greasing process.
The end user thinks it's a good idea to 'sweat the cosmo out', so they expose the inletting to heat with the grain of the wood unsealed and wide open - like a sponge. As the wood is heated, the grain opens up and allows the cosmo to flow into it because cosmo is runnier/less viscous when it's hot. At some point, after enough cycles, 'cosmo removal' done this way will reach diminishing returns and the wood will have been impregnated (sweated in) with cosmoline. Very difficult to get it out now.
That's why the best method of cleaning cosmoline off of wood is with a mild cutting solution (all I've ever used is glass cleaner). This can be done in an hour or less of thorough cleaning with strips of old towel saturated in solution and discarded once they start depositing instead of removing the cosmo. The solution will flush the cosmo out of the open fibers of the wood leaving the inletting grease-free and ready for a light coat of oil after being allowed to dry for a day or so. Then there's no need to sweat anything out because there's none left to sweat.