On Tue, Sep 14, 2004 at 01:00:30PM -0400, Byron A Jeff wrote:

Answering some of my own questions. Found a muratic acid site targeted for
cleaning masonry here:

http://www.naturalhandyman.com/iip/infxtra/infmur.shtm

> Procedure:
> 
> 1) Mix 2 parts 3% hydrogen peroxide with 1 part 32% hydrocloric acid, in the
> form of muratic acid from the home improvement store. 
> 
> 2) Add stranded copper to dissolve in the solution.
> 
> 3) Bubble with air to add O2 to the mixture to get stable CuCl etchant.
> 
> Questions:
> 
> 1) Is the above procedure correct?
> 
> 2) chem question: does it matter how the HCl and H2O2 are mixed? In some 
> mixtures one reagent need to be stirred into the other. Is that the case here?

The answer is yes. From the site above:
-------------

IMPORTANT: Always add acid to water... never add water to acid!!  To quote a
knowledgeable reader, Tommy from Corsicana, Texas:

    "When water is added to muriatic acid, an exothermic (heat is given off)
    reaction occurs.  This is often accompanied by a violent "belch" which
    propels the acid mixture out of the container and onto the person making
    the dilution!  This occurs because the heat generated by the reaction is
    under the cooler water and causing it to expand rapidly.  When the acid
    is poured slowly into the water, the cooler water layer is on bottom, so
    the heat generated is dissipated upwards at a slow speed."
--------------

Note that the H2O2 we're using is only at 3% dilution with the rest as
purified water. So I figure it's best to substitute H2O2 for water above to
get

IMPORTANT: Always add acid to H2O2... never add H2O2 to acid!!

The site also follows up with the fact that pouring the acid first can cause
it to splash. So it should be H2O2 first, then acid.

> 
> 3) Are all plastics etchant safe? So bubbling air in a plastic tube is 
> sufficient, right?

Again from the site:

---
 Do not mix in a paper, ceramic or metal bucket... use a plastic bucket.
 Glass containers are also acceptable for measuring and mixing.
---

Still looking for my other answers.

Thanks,

BAJ
_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist