[Rockhounds] concrete/cement - phosphoric acid

[Erich Kern]

No, it's not toxic, it's mildly corrosive. Big difference. 

BTW, one of the digestive fluids our stomach makes is HCL (hydrochloric acid) to render some of the minerals in vegetables soluble. People with chronic bulemia eventually lose their teeth because the HCL they throw up dissolves the enamel coating on teeth.

Corrosive is not necessarily toxic (i.e. a poison).

Erich Kern
Murrieta, CA


----- Original Message ----- 
From: Armando Afonso 
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors 
Sent: Tuesday, October 23, 2007 1:29 AM
Subject: Re: [Rockhounds] concrete/cement - phosphoric acid


A sugestion: Phosphoric acid is used to clean sewage pipes of cement 
residues.
Try it, with care. It is toxic!

----- Original Message ----- 
From: "Alan Goldstein" <deepskyspy at insightbb.com>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" 
<rockhounds at lists.drizzle.com>
Sent: Tuesday, October 23, 2007 4:02 AM
Subject: Re: [Rockhounds] concrete/cement


> It should remove the concrete residue quite easily. I'd use a small amount 
> in a gallon of water. Don't get too close to see if it is working! You'll 
> hear it fizz. The fumes are quite potent even in small amounts. Make sure 
> it is an open, airy space. Leave it in overnight. Soak it in fresh water 
> for a while afterwards just to be safe.
>
> Alan
>
>
> ----- Original Message ----- 
> From: "June Young" <jayhawkmn at yahoo.com>
> To: <rockhounds at lists.drizzle.com>
> Sent: Monday, October 22, 2007 5:33 PM
> Subject: [Rockhounds] concrete/cement
>
>
>>I have a piece of jasper  that appears to have concrete/cement on it.  I 
>>have picked off a great deal of the concrete but it still has a white 
>>colored coating.  Will muratic acid take off this final layer?  If so, 
>>should it go in at 100%?  How long should it stay in?  Will it need to be 
>>scrubbed with a steel brush?  Does muratic acid loose its effectiveness if 
>>it has been around for many years?
>>  Thanks for your help.
>>  June
>>
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