Hello Sandra,
first, all those metals you mentioned have been used by humans since.
the bronze age. but that doesn’t mean they were safe!.In many
countries brasses are still used for trays, coffee brewing, tea,
etc. and copper cookware is prized for certain things- like
confectionery- so it depends what you are going to put in the vessel
as much as the metal you make it from and solder (if any is necessary
- cold connections being preferable in say, riveting a handle that
may contact a liquid inside, to the piece) Things to consider:
Copper items you make for cooking should be lined with a lab grade
tin- if you don’t have it applied only things that are non-acidic can
go inside safely and that is to cook in the vessel not to store
anything. Older copper wares had some arsenic or lead- so it is no
longer legal to manufacture non-lined articles for the international
market, and using them should be done cautiously with only
confectionery in mind if that is your only choice- generally copper
items are too thin to be useful for the high temps required but for
quick processes like caramelising they are brilliant.
If you want to make a serving tray, use a pure copper sheet, don’t
try alloying with tin (as in brass or bronze better to buy it)
Jeweler’s bronze - also called Merlin’s gold (Alloy 320) 85 copper
/15 Zinc composition that has a colour like high karat gold but is an
alloy of copper and zinc and contains nolead, and has a high copper
content- but is also reactive. You shouldn’t use it unless strictly
for water based beverages like teas, tissanes, infusions, etc, Not to
store any of them in as the tannic acid in typical black teas will
taste off once it reacts with the zinc in the alloy. The tannins are
rather oily and coat almost any metal if allowed to build up (that’s
why coffee at many food service establishments tastes awful! and tea
dispensed from large aluminium urns with a lever type spigot are
equally terrible as workers may (if lucky) run the unit through the
dishwasher but rarely get all the tannins built up around the spigot
assembly (the intake and output) off as it takes handwork.
Yellow brass- (alloy 260) is a 80 copper / 20 Zn alloy and is harder
than copper or jeweller’s bronze,& contains no lead. But again the
same acids (tomato products, citrus, etc.) will cause leaching and
some times , discolouration on the interior. It is also true that
some distributors sheet has reclaimed copper in it and unless the
company offers a graded or certified grade of X then you have no way
of knowing if its all new metal, or a recycled product -particularly
when ordering from online auction sites.
All in all I would avoid the copper vessel for cooking idea entirely
if you aren’t familiar with the industrial grades and FDA regulations
(as well as a few other trade and manufacturing organisations
opinions or rules) and buying options. You can have vessels plated
with tin (lined is a truer description of the service as it’s a bit
denser and thicker of a coating- most plater’s that serve jeweler’s
don’t do this service as a rule) but it’s costly and DIY isn’t
recommended if you think you can do it yourself. one can, but
probably shouldn’t unless you have excellent insurance or provide a
disclaimer that it’s decorative and not intended for food uses. I
certainly don’t want to discourage anyone from making something they
want to try, but without some experience with cookery and metals, and
hollowware crafting in safe for food alloys I wouldn’t suggest
experimentation save fro the crafting of it. If you want to make a
food safe item use .999 silver ! Many people that are sensitive to
copper, nickel and alloys that contain either of the metals on their
skin will often feel an “unexplainable” gastro-intestinal related
problem after consuming foods, etc. made in copper, brass and bronze
vessels, so there’s another consideration. Leaching the main problem.
Non-food safe sheet metals second. Third, alloys and solder seams not
sealed with a food safe or clad with a high tech coating shouldn’t be
sold for uses that involve consumption.
one company i know of, but have zero affiliation with, that sells
their own “craft” metal sheets is something like whimsie, or house
of whimsie, don’t know off hand- but they sell non-lead jeweler’s
bronze and yellow brass that could be used for holloware but as sI
recall the largest sheets they sell are perhaps 16x16 and only in a
few gauges. sorry i don’t have more info. If you have questions feel
free to contact me off list. rer