[Sca-cooks] Bronze Cookware

[Saint Phlip]

Well, I just discussed this with a friend who's a chemist, and he
brought up some interesting points. What I find interesting is that
even tinning a lead alloy doesn't prevent the lead from migrating.

Phlip,

I don't know for sure, but I'd bet that lead will etch out of the
surface of such a vessel whenever anything acid (or maybe also
alkaline) is put in it.

Try this experiment:  Take some yellow brass (not bronze - you want
zinc) scrap.  Grind the surface if it isn't obviously yellow.  Put it
into vinegar + salt  and watch what happens. It will "turn into
copper".  You etch the  zinc out of the surface of the metal, leaving
only the copper to provide the color.

Now, why WOULDN'T this happen also for lead?  Lead solder can easily
be pickled off copper fittings with muriatic acid.

The question remains how deep the pickling will go -- is it possible
to pickle out all the available lead and leave behind a lead-free &
therefore safe surface?  The only way to tell is to experiment, which
means being able to test the pickle solution for lead.  You could read
up on doing that if you like.

An alternative would be to pickle off the surface lead and then tin
the whole surface with 100% pure tin.  You must remove the surface
lead first or it would migrate into the tin coating.

And be aware that metals alloyed with lead are not necessarily
homogeneous.  I understand that the lead will migrate to the surface
of the brass.  California now requires key manufacturers to label
their keys as hazardous because of this unless either they have no
lead or they're coated to prevent lead contamination of the fingers.

Take care,

Bruce
- Hide quoted text -

On Mon, Aug 30, 2010 at 9:52 AM, Saint Phlip <phlip at 99main.com> wrote:
> Having a discussion on the Cook's List about bronze pots with lead as
> part of the bronze. The discussion is about the safety of eating out
> of them- lead is about 5% by weight- in period, there may have been as
> much as 20-30% by weight, My thought was that thew lead might be there
> because of being alloyed with the tin, whether accidently or on
> purpose.
> You got any thoughts?
>
>
> --
> Saint Phlip

On Mon, Aug 30, 2010 at 11:49 AM,  <wheezul at canby.com> wrote:
>> If/When I hear more from Hampton Court, I'll pass it on.  At this point
>> it sounds as if they use the pots and don't have any problem with lead.
>>   A subsequent post by a non-Hampton Court cook posited that period
>> bronze cookware could have lead content up to 20 or 30 percent.  That
>> would make the current 5 percent fairly low.
>>
>> Alys K.
>> --
>> Elise Fleming
>> alysk at ix.netcom.com
>> http://home.netcom.com/~alysk/
>
> Wasn't the real concern verdigris poisoning from copper?
>
> Katherine
>
> _______________________________________________
> Sca-cooks mailing list
> Sca-cooks at lists.ansteorra.org
> http://lists.ansteorra.org/listinfo.cgi/sca-cooks-ansteorra.org
>



-- 
Saint Phlip

So, you think your data is safe?
http://www.cnn.com/2010/OPINION/01/23/schneier.google.hacking/index.html?hpt=T2

Heat it up
Hit it hard
Repent as necessary.

Priorities:

It's the smith who makes the tools, not the tools which make the smith.

.I never wanted to see anybody die, but there are a few obituary
notices I have read with pleasure. -Clarence Darrow