Classical Numismatics Discussion
  Welcome Guest. Please login or register. 10% Off Store-Wide Sale Until 2 April!!! Explore Our Website And Find Joy In The History, Numismatics, Art, Mythology, And Geography Of Coins!!! Expert Authentication - Accurate Descriptions - Reasonable Prices - Coins From Under $10 To Museum Quality Rarities Welcome Guest. Please login or register. 10% Off Store-Wide Sale Until 2 April!!! Explore Our Website And Find Joy In The History, Numismatics, Art, Mythology, And Geography Of Coins!!! Support Our Efforts To Serve The Classical Numismatics Community - Shop At Forum Ancient Coins

New & Reduced


Author Topic: De-ionised Water?  (Read 5969 times)

0 Members and 1 Guest are viewing this topic.

Offline Mickey H

  • Praetorian
  • **
  • Posts: 16
De-ionised Water?
« on: September 04, 2013, 12:49:12 pm »
Hi there,

I am just starting to clean several coins purchased from a Roman middle eastern hoard. I currently have a couple of bottles of de-ionised water (as opposed to distilled water). Just wondering if anyone has any experience of using de-ionesed water.

My understanding of the distilled water cleaning process is that it essnetially leaches off mineral deposits from the coins surface, hence I think de-ionised water should do the same job, just wonderign if anyone has any experiences of this. I have looked elsewhere and couldnt see the topic covered - apologies if this has been raised before.

Any help would be very gratefully recieved.

Many thanks

Mickey

:)

Offline ModernCoinTraitor

  • Praetorian
  • **
  • Posts: 77
  • First ancient coin
Re: De-ionised Water?
« Reply #1 on: September 05, 2013, 09:21:41 am »
Deionized water is "made" by passing water through a R-H/R-OH resin bed where ions are removed based on the affinity scale particular to the resin used. In most cases, the highest priority is to remove Sodium, Chlorine, and so on. The resin also acts as a filter removing some particulate. The process of capturing an ion results in the release of another ion. Either H+ or OH- in this case. The result is pH balanced water that is free of highly reactive contaminant ions.

BUT, it does not remove all contaminants.

Additionally, as resin is filled with these contaminants, it starts to run out of H+ and OH- ions to release. This is where the affinity scale kicks in... because the resin prefers Sodium, it may release another contaminant to capture the Sodium. This is an indication the resin is "depleted."

Companies have specifications on how much of these contaminants can be "left behind" and still be called "deionized" water. Those contaminants will eat your coins.
-----
Distilled water is created by boiling the water and condensing the steam. Particulate will not boil and remains behind in the brine solution. Almost all other ions separate from the water as a gas and fail to condense with the water. These are removed by air evacuation systems. The result is pure water.

This water is cointained in tanks and moved through pipes. Both introduce trace amounts of metals into the water as ions and particulate.

Immediately after the water is condensed, chemistry takes over. The container holding the water leeches some compounds into the water. There is not much you can do about this one, but it is usually benign to the coins.

Air above the water can be absorbed into the water, especially carbon dioxide, which converts to acid, eg. carbonic acid from carbon dioxide. This takes a few days to become harmful to coins, and can be limited to the air above the water by using a lid on your containers.

So, heed the advice to change out your water at least once a week, use small inert containers, fill them nearly full, and keep a lid on the container. Otherwise, even distilled water can damage your coins.

Offline daverino

  • Caesar
  • ****
  • Posts: 543
    • My Gallery:
Re: De-ionised Water?
« Reply #2 on: September 09, 2013, 08:49:48 pm »
Whether de-ionized or distilled the water is more than pure enough for cleaning or washing coins. Many coins have a fair amount of soluble salts- particularly sodium chloride- on them which a water soak will remove. Personally I think that ordinary tap water will do just as well since most city water is quite pure.

In the past a lot of people who soaked their bronze coins for long periods reported green spots of corrosion. I would avoid soaking coins for a long time (days) since it shouldn't take that long to free them of corrosive salts and acids and you might find bad side effects if you leave them in water. Traditionally olive oil has been used to loosen deposits. As a non-electrolyte it will not promote corrosion.

Offline Mickey H

  • Praetorian
  • **
  • Posts: 16
Re: De-ionised Water?
« Reply #3 on: September 10, 2013, 05:42:36 am »
Great stuff, thats very informative. Thanks guys.

I have left them in for a week now, think I will scrub them and swap them over to olive oil, as this seems to be the de facto standard.

Many thanks for your comments.

much apprieciated

Mickey

Offline Lee S

  • Comitia Curiata
  • Conservator
  • Caesar
  • ****
  • Posts: 1561
  • γεια μας !!!
Re: De-ionised Water?
« Reply #4 on: September 10, 2013, 08:51:59 am »
I have never had any bad effects with distilled water.... frequent water changes and scrubbing ( every day at first, then weekly..) have never damaged any of my coins...

  I have had good results with olive oil, but it takes a LONG time ( over a year with some coins ) and does tend to darken them, plus olive oil is acidic, so for me I think there is more chance of damage from oil than from DW.

Offline daverino

  • Caesar
  • ****
  • Posts: 543
    • My Gallery:
Re: De-ionised Water?
« Reply #5 on: September 10, 2013, 08:35:19 pm »
An alternative to olive oil is WD-40. It is more expensive than olive oil and requires that you keep the coins in a sealed container since it is volatile. But it is a very good penetrating oil and if you are handling only a few coins at a time (as was my practice) it is convenient and less messy than olive oil. Possibly also more effective. It also darkens coins but that is because it penetrates well. I found that within 24 hours after cleaning with it  the darkening disappears entirely as the WD-40 evaporates in air.

Of course there is always  a fair amount of patience and elbow-grease required whatever the method.

Offline Tony A

  • Consul
  • ***
  • Posts: 312
Re: De-ionised Water?
« Reply #6 on: September 20, 2013, 10:42:06 pm »
I would hesitate to use WD-40 for cleaning since it has some rather harsh agents that make it great for cleaning guns and rusty pipes, but it could damage a coin or artifact by stripping off the patina. Plus, ancient coins have a lot of impurities that the solvents and rust inhibitors in WD-40 can interact with and possibly cause some discoloring. You might have better results - if you go that route - using an extremely light oil of the type used for precision electronics (such as a shaver or sewing machine).

Olive oil probably isn't the "standard" for most cleaners these days. It is slow acting (which can be a plus) but I think most on here would agree that the results are quicker with DW with less chance of damaging a coin. DW is a lot less expensive than olive oil, too.

Just my thoughts ...

Tony


Offline daverino

  • Caesar
  • ****
  • Posts: 543
    • My Gallery:
Re: De-ionised Water?
« Reply #7 on: September 21, 2013, 11:56:36 pm »
I would speculate that the tradition of olive oil cleaning got started in the Mediterranean area where there are lots of olives as well as ancient coins. Perhaps a trove of encrusted ancients would be thrown into a barrel of oil for a year or two or three. From time time to time some peasant ladies would take them out and pick away at the coins for pennies an hour. Of course modern coin cleaners don't usually have the time, patience or cheap labor available for this. Olive oil is not naturally acidic but (like all organic oils) it will react with air and slowly become acid especially if also exposed to light and metals like copper. If you use olive oil it is best to keep it away from direct sunlight  but you can hardly avoid copper when you are cleaning bronze coins!

The chemical components of WD-40 are quite inert so am not sure what Tony means when he says that WD-40 or other petroleum-based oils will discolor or damage coin patinas. WD-40 might possibly dissolve away surface greases and waxes leaving the patina  looking a bit dull after cleaning but this is why some people "rub up" coins - to restore the gloss.

Offline Tony A

  • Consul
  • ***
  • Posts: 312
Re: De-ionised Water?
« Reply #8 on: September 22, 2013, 08:05:48 pm »
Daverino -

WD-40 has low amounts of solvents to cut grease and remove rust, and I'm a little concerned about how they might interact with the inherent impurities in ancient coins.

I can't say I have any experience with it on coins so I'll defer to experience. But years ago I worked for an oil company that made specialty lubricants for various defense industries and NASA, and saw all sorts of solvents and compounds added to virtually every product we produced. (We didn't make WD-40, however, and chemistry is not my area.) Even trace amounts of some of those additives can effect how a lubricant works, even if it only results in a little toning from the residue (in this case, a sort of re-patination). I don't think any of it would necessarily harm a coin, but would guess it might result in a few spots or blotches. Again, I haven't used WD-40 on coins but it just follows that it has to have at least some potential effect that may be less than desirable at times.

Tony

Offline gustrot

  • Praetorian
  • **
  • Posts: 31
Re: De-ionised Water?
« Reply #9 on: October 12, 2013, 07:42:21 pm »
I have always heard that ions had a great role in cleaning power of distilled water, and that it was the reason you have to change the bath on a regular basis. ???

I guess that if this is true, de-ionised water is not a good idea...

Offline daverino

  • Caesar
  • ****
  • Posts: 543
    • My Gallery:
Re: De-ionised Water?
« Reply #10 on: October 14, 2013, 10:42:05 pm »
De-ionized (DI)  and distilled water (DW) are pretty much the same inasmuch as the impurities, which are mostly dissolved ions, are all removed but by different means. Most impurity ions don't help in cleaning. In fact they are something of a problem. If salt is present in the coins it is leached out and makes the water salty - and salt water plus metal causes corrosion. This is a major reason why, if you are using water soaks, that you need to change the water regularly.

Another ion which can have a major effect on cleaning is the acid ion (H+). In a mild form, like lemon juice or vinegar, it is very useful in cleaning encrustations from coins made of 'good' silver.  Hard-to-remove crusts, not just dirt, are made of dirt or clay which has been hardened to a rock-like nature by deposits of calcium carbonate, otherwise known as limestone. The acid will slowly dissolve crust deposits without bothering the silver. I expect it would do just as well on bronze "crusties" except for one problem. The acid ion will remove the patina as well as the crust from bronzes and so it is to be avoided if you are soaking base metal coins. It is a further reason to change water on a regular basis.

 

All coins are guaranteed for eternity