[Rockhounds] concrete/cement - phosphoric acid

[Armando Afonso]

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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