Solvents, even ethyl alcohol, should not be used on ivory except by experts. As you know, alcohol can remove the water from the surface layers. We do use it sometimes, but only in a very limited way and mixed with other things so as not to dehydrate the ivory surface. Other solvents may affect the organic constituents of the ivory.

I am most concerned about the use of lemon juice, which is acidic. Since ivory is part mineral and those minerals are susceptible to attack or etching by acids, I would not recommend using lemon juice or slices of lemon. Yes, the ivory will look better at the time of cleaning because it does remove the dirt, but it also may remove or etch the surface of the ivory.

I also would avoid using salt on ivory since salt can be abrasive and also residues may remain in the porous surface and be activated later causing damage to the ivory.

As for using wax, we don’t usually apply surface coatings to ivory. There are often solvents in these coatings or they require solvents for later removal that may be harmful to the ivory. Also, since ivory is a porous material, anything used on the surface will penetrate to a certain degree, so it can never be removed completely. Using solvents to remove the coating may drive it in even further. As you may know, different waxes have different properties and some may attract and hold dust even if the excess is removed, and some may yellow and cause staining.

Although such cleaning and coating as was suggested may make the ivory look better at the time (and give a feeling of satisfaction), in my opinion it is not in the best interests of the long-term preservation of the ivory."

If you come across similar advise, please ignore it.