Since Renwax is not soluble in water, not only would it not "hydrate" the surface, but rather "seal" the surface from absorbing (or adsorbing) water.
I couldn’t figure out the best word to describe what happens when the porous, whitish surface gets darkened and filled. It looks similar to being wet, I guess. I’m no scientist :/
I use it on bronze coins to protect them from the elements. Best way in my opinion is to use a heat gun to bake the coins to remove the moisture on the surface and surrounding the coin, then after the coin cools down a little bit, I apply the wax to the coin with my fingers and then use a micro fiber to carefully buff everything and I try to strategically buff certain areas of detail on the coin.
If you don't know what cerumen is, look it up... Now, as to the practice of adding anything to a coin's surface, it could be done to increase the eye appeal or to protect the surface from the rigors of environment including handling and atmospheric contaminants. Renwax is a "microcrystalline wax" and if you search that term, it isn't very unambiguous. Petroleum byproduct...hmmm. I'm assuming it is mostly hydrocarbon. We all have a picture in our heads when we hear "acid" of a bubbling vat that will dissolve whatever goes into it, but when you drink milk, you get a healthy dose of lactic acid, citrus fruits have citric acid and ascorbic acid (vitamin C). Waxes, in general are long chain (lotsa C atoms linked together) "fatty acids" and compounds made from these. AFAIK they will do no harm to coins either short term or long term. The "shiny" appearance that coins take on after use of any wax (or oil) is due to the wax or oil filling in the voids (pores) in the coin surface. The coating would give the coin protection from handling or environmental hazards and could be removed when desired. As far as allowing BD to proliferate, every effort should be made to get all BD off and assure the coin is DRY, even if this requires putting it in a warm (not hot) oven for awhile. BD will not grow in the absence of moisture and the wax will seal the surface from moisture. Something I have wondered for awhile is the use of linseed oil on coins. Linseed oil is the "oil" of oil paints. It goes on as a thick liquid but then reacts with oxygen in the air (an advantage?) to cross-link and form a polymer. Anyone have any thoughts on this? Finally, a question for @Insider and/or @Barry Murphy about coins treated with Renwax and some such. Would this keep them from being certified?
I've never used it. I believe it is used mainly on ancients or coppers. If it were put on a coin and was detected, I would give it an A/S. I cannot speak how the NGC authenticators treat it. Remember, at one time lacquering coins was a good thing to do to protect them.
I've only used it in a few cases, primarily after cleaning or treating a coin. I do prefer keeping my bronzes free of any wax or sealant. Here's a Cleopatra VII 80 drachma after cleaning and treatment (some BD). So far the green areas are hard and inert. The Renwax does provide some gloss to the coin's surfaces.
Just for fun, you can rub some petroleum jelly (a little dab'll do ya) into the surface and it's easily removed with acetone or xylene.
