Cleaning Coins With Dry Ice

Possibly because the cooling happens too slowly since dry ice is a solid. Might try liquid nitrogen. Much colder and a much faster cooling

I hope you didn't breath in any of those fumes. Not good for lungs or any part of your body.
Hopefully people always check with the ATSDR website prior to using anything of suspect of creasting danger.
The main problem with any cold method of coin cleaning is the great condensation of moisture as such coins return to room temperature. And such condensation could form gasses on those coins that normally would take years to effect a coin and now it is there in a fraction of a minute. Pending on such air in the area you could be placing worst stuff on the coins than what came off. And too, if you touch such frozen coins with your fingers, you now leave moisture, acids, oils on them at an even faster rate.

The solution to this problem is after you have "cleaned" them with the liquid nitrogen put them in a small contained of the liquid Nitrogen and leave it alone for the nitrogen to boil off and then just wait for the coin to return to room temperature before you remove it from the container. As the nitrogen boils off it displaces eveything else and the coin ends up sitting in a container of dry nitrogen gas which is practically inert. (Which being heavier than most other atmosphetic gases will remain in the container and keep out moisture and other contaminates.) Once it is back to room temperature you can take the coin out without having to worry about things condensing on it.

It was on the show Modern Marvels (which is on the History Channel) they showed how it comes out as a liquid but upon contact with a solid surface, becomes a gas and shrinks the dirt particles on the item to where they'd just fall away from the metal. Found a unit on ebay for $4,000 - but there must be commercial users of such a device as well. Might be interesting to try & report back - someone at sometime or other must have tried this form of cleaning.

Why is a 3-1/2 year old thread back on the front page?

www.coldjet.com - to find a local contractor in your area

www.co2techno.com - video on this homepage

I googled the subject & this old page came up.
A dry ice cleaner was @ my work today (Baxter Healthcare) going to contact them & see what they can/cannot do. NOT a liquid, actually rice-sized CO2 pellets blasted @ a surface which dissipate to a gas form upon contact.

What is Dry Ice Blasting?

In the simplest of terms, dry ice blasting (sometimes called dry ice cleaning) is a form of non-abrasive blasting, where dry ice, the solid form of carbon dioxide, is accelerated to supersonic speeds in a pressurized air stream, and directed at a surface in order to clean it.  However, the technology, and equipment needed to make this happen are anything but simple.


This method is similar to abrasive forms of blasting such as sand blasting, bead blasting, or soda blasting, in that a media is used for blasting.  

But that's where the similarity ends. Instead of using hard abrasive media to grind on a surface (and damage it), dry ice media is actually quite soft, and is much less dense than other media used in blast cleaning.  Upon impact, the dry ice sublimates almost immediately, transferring minimal kinetic energy to the surface.  This produces minimal abrasion.  The sublimation process absorbs a large volume of heat from the surface, producing shear stresses due to thermal shock  The dry ice expands to 600 times it's original size upon impact.  The rapid change from solid form to gas also causes microscopic shock waves, which assist in removing the contaminant.  After sublimation, there's no water, no moisture, and no chemicals left behind. The only thing left is the contaminant that was blasted off the surface, ready to be easily picked up.