I set slate tiles in my bathroom floor and counter top. I notice that where essential oils (aroma therapy types) have dropped on the surface, the shine is gone and the sealer appears to have been eroded.
I sealed the surfaces with several coats of run of the mill sealer from the home improvement store.
Is there something better to apply over the existing sealer?
If the cheap sealant was water based then you can top that with another water based sealant, but I don't think that would solve the problem. The essential oils are eating away the water based coating. You will need to chemically strip the old coating then coat with a penetrating sealant that says it protects against oils.
In general, putting a solvent-based sealer on top of a water-based sealer is a bad idea. The solvents can eat or soften the existing water-based sealer, destroying both coatings. Think of it along the lines of oil and water; they do not mix.
If you do want to switch to a solvent-based sealer, you will need to chemically strip off the existing water-based sealer before applying the solvent-based product. Source
