Cleaning beerstone {was: Re: [Rockhounds] muriatic acid forcleaning...!?????!!!}

[Lawrence Rush]

I have sometimes cleaned up the oxalates by preparing a fresh, clean 
solution of the oxalic acid, and re-soaking the specimen. The new solution 
must be fresh, and strong, and watched carefully, removing and neutralizing 
the specimen as soon as the oxalates are dissolved.

I am not a chemist, and don't quite understand why this should work, but it 
has for me.

Larry Rush


----- Original Message ----- 
From: "Kreigh Tomaszewski" <Kreigh at Tomaszewski.net>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" 
<rockhounds at lists.drizzle.com>
Sent: Sunday, September 02, 2007 10:45 PM
Subject: Cleaning beerstone {was: Re: [Rockhounds] muriatic acid 
forcleaning...!?????!!!}


> If you end up with calcium oxalate, how do you clean it off? It is not
> very nice stuff.
>
> Calcium oxalate turns up as a byproduct of brewing beer, coats tanks,
> and opens the door for spoiled batches. The crystals shield undesirable
> organisms. The industry calls it beerstone, and takes measures to
> control it.
>
> As a rockhound you might know it as Whewellite.
>
> Calcium oxalate also appears in some poisonous plants, and is a major
> component of kidney stones. When ingested, even small dosages are very
> not nice to humans -- and moderate doses can kill you. It is why you
> don't eat rhubarb leaves.
>
> The beer industry uses periodic treatment with caustic (2-4% lye) hot
> (185F) water solution followed by warm (140F) phosphoric acid (1-2
> oz/gallon) _OR_ a warm phosphoric/nitric acid solution (1-2 oz/gallon)
> followed by a warm noncaustic alkaline cleaner (1-2 oz/gallon). Both
> assume a final (usually high pressure) hot water rinse followed by tap
> water until drain ph is neutral to the tap water. The acid and alkaline
> compounds can neutralize each other, and be diluted, if a sufficient
> holding tank is in the drain; 15-30 minutes flow treatment per stage.
>
> Have any of you successfully cleaned calcium oxalate (off, probably,
> quartz)? What worked?
>
> Kreigh
>
>
> Flint Smith wrote:
>>
>> Just so we're complete here, HCl is used as a pre-treatment if you plan 
>> to remove rust stains using oxalic acid.  The plan is to avoid forming 
>> calcium oxalate.
>>
>> Right?
>
> -- 
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