I try not to mix my olive oil soaked coins with distilled water soaks afterward, If the coins have soaked in olive oil long enough, the crud will have absorbed enough oil to repel the water and the soaks are ineffective (I have found).
I can go from water to oil but never oil to water with results.
I use olive oil because of its reported acidic qualities. WD-40 is basically a low grade kerosine or jet fuel, it isn't really an oil and if you let it evaporate leaves a horrendous sticky residue (never let it touch your firearms if you own them! Use a true oil). WD-40 is a water displacement liquid, hence the WD in its name. It will drive water out of a porous or dirt caked coin but you will want to use oil soaks afterward due to the petroleum content, it will repel water after WD-40 soaks.
I don't bake, but I do boil coins. When they first arrive I boil with a
bit of sodium carbonate (washing soda) or maybe some Dawn dishwashing detergent if we have it on hand. I boil for 5 to 8 minutes or so, the majority of loose crud and dirt
comes off at this stage, or the stubbord dirt is at least revealed to make distilled water soaks more effective.
I scrub with a toothbrush and
work with a sharpened brass and copper rod, those are my most commonly used
tools. I will use a diamond dusted
pick in teh manner Mayadigger reccommends if I have coins that will respond well to them.
I almost never use ammonia or inegar (vinegar occasionally on
billon or silver coins in diluted solution, just to
help bump a soak, and only for a few minutes at a time. Lemon juice is
good too.
Ammonia finds uses in repatinating stubborn coins that
had to take a dunk in teh zapper. i know, its not popular in many circles, but I buy lots of lower priced uncleaned coins and crusties, it keeps me finding decent stuff. I have mananged to hone my zapping skills pretty well, and always note on my
attribution if a coin has a false
patina, some folks would never buy that coin should I have to sell one day, and I believe in honesty. Do unto others and all that...
Under
good light and with a wet coin, you SHOULD be able to tell a hard, smooth clay layer from
patina. Some coins are tough though like you say, just continued distilled water soakes will eventually wear the
patina down a
bit if it is a
patina, and sooner if it is clay. A diamond dusted
pick comes in handy to determine the makeup of the layer you are dealing with.
That's just my way, I have some other, more unconventional methods I try on stubborn coins before they get
zapped. Ultra
fine diamond dusted Dremel bits, sculpting bits, jewelers bits, etc. But for daily scrubs it is a toothbrush, trimmed short to resharpen the bristles ocasionally.
