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Author Topic: Hydrogen peroxide  (Read 3095 times)

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Offline moonmoth

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Hydrogen peroxide
« on: October 31, 2008, 02:45:22 am »
A warning for anyone tempted to try using a strong concentration of hydrogen peroxide to clean a coin (that is, if you can get hold of it, which won't be easy):

I just watched a TV programme in which a man flew using a personal jetpack.  The fuel is 90% hydrogen peroxide.  It is activated by contact with silver, upon which it turns into superheated steam at 1400 degrees Fahrenheit (= 760 degrees Celsius) .. which is not something you want around you and your coins!

Bill
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Offline larry c

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Re: Hydrogen peroxide
« Reply #1 on: October 31, 2008, 05:59:06 am »
Also used as a oxidizer in rocket fuel by NASA & the military! :)
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Offline bruce61813

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Re: Hydrogen peroxide
« Reply #2 on: October 31, 2008, 10:03:41 am »
I may have made a comment a very long time ago about hydrogen peroxide and cleaning. It is effective at breaking down organic materials, but will not work against inorganics. What does that mean in cleaning?

1. If the coin is coated with hard clay, but not lime, it will break up the clay or at least soften it. The super fine mineral particles that make up clay are bound together by organic materials.

2. It is ineffective against mineral deposits like lime, and some other water deposited minerals,many of which won' dissolve with just water once they form.  These often require high temperature water to re-dissolve.

just some thoughts

Bruce
too many coins - too little time!!

Offline larry c

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Re: Hydrogen peroxide
« Reply #3 on: October 31, 2008, 10:57:28 am »
Bruce is correct. I've used 3% peroxide and it does help is some cases, but
as with all chemical cleaning should be used with care and in small steps.
Sometimes that bit of clay or deposit covers a ugly pit or crater!
Some coins have better eye appeal partially cleaned( think desert patina)
then completely clean showing a rough, pitted flan. Peroxide is also
rough on the skin so use gloves!
There is no magic bullet. :)
“Do you have the patience to do nothing"

CzarMike

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Re: Hydrogen peroxide
« Reply #4 on: October 31, 2008, 03:29:01 pm »
10% peroxide can get quite volatile, but works great on Balkans coins because the the dirt in that area is mostly decomposing plants.

Offline casata137ec

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Re: Hydrogen peroxide
« Reply #5 on: October 31, 2008, 10:36:37 pm »
There is no magic bullet. :)

Exactly...I have not had any noticably better success using peroxide over dw...on any type of dirt. I am sure it has it's place, especially the stronger concentrations, but for me and my small lots, it wasn't worth the trouble.

Chris
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Offline SC

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Re: Hydrogen peroxide
« Reply #6 on: November 03, 2008, 02:40:57 pm »
I have been experimenting with HP quite a bit recently.  Just the 3% stuff though. 

I have only used it a room temperature though reading through old threads people seem divided over whether to warm it or not.  If warmed some said to use a double boiler, other the microwave (warm it before you add coins).  As I said I have only done it at room temperature.

As several others have said, it seems to work well on most soils and even soften some lighter encrustations.  I check the coins after about an hour and then after a few more hours.  I have taken some out at the first or second check and left others in overnight.  By morning the coins have stopped bubbling and I think the HP is now simply inert DW.  It is very dirty and cloudy.  I usually fill a small bowl to about 1" depth and work on 5-10 coins.

I have tried on coins that were in DW soaks for months.  In some cases (maybe 1/4) the hard dirt that was not budging with the DW softened so I could pop it off.  In the rest of the cases no real effect yet.  I have only placed these coins back into DW.  I have not yet given any batch of coins multiple soakings in HP.  Not sure if that would be too much for the patina to take.

I have also done a few "initial soaks" with HP.  I did a rinse in warm tap water then into the HP.  This seemed to work better than DW for an initial soak but certainly did not remove or soften all dirt.  (And was way more expensive!)

I always soak in DW after soaking the coins in HP.

So far I see no signs of damage to the patina or coins.  That said I have not done this on any coins which clearly had a very nice patina showing through.  Only on the "average" types one finds in Balkans etc.

I will keep experimenting but at this point I think HP might be a good soak for coins with stubborn dirt after they have had a few months of DW soaking.

Shawn

SC
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