Chemically clean?

Why don't you just use gun black (or it could be called gun blue)
from any gun shop? It colours black on all brass and bronze and
very easily. It works just like LOS but you don't have to mix it up
and can use the liquid for years as long as you close the bottle
tightly. 

I was unaware that gun bluing worked on anything but iron or steel.
Thanks for the suggestion; I’ll get some and see what it does.

Steve

Hi Judy,

I use only a slurry of pumice and water to clean metal before
etching. Presumably, there's no "detergent effect" in that
situation. 

One could get into this issue very deeply. Water has a specific
surface tension which means that it forms droplets. Lots of factors
will affect that tendency. Grease on the surface of the metal will
obviously make it bead more readily than if the surface was clean.
The addition of a detergent which reduces the surface tension of
water and also dissolves the grease, will clean the surface and
produce the sheeting discussed. However, as I said, once it’s rinsed
properly, the normal surface tension of water will be restored and
you will see beading again, but not as much as when the surface was
greasy. The addition of substances such as pumice will also affect
(reduce) the surface tension of water and therefore clean the metal
(but in a different way to detergent). Don’t worry about it too
much. I’m probably getting too technical. Carry on doing it the way
you’ve been doing it - it works so why knock it.

Helen
UK

How long would I have to rinse the metal to know if the results are
positive or negative? 

I’m not quite sure I know what you’re asking. Unless you go into some
physical chemistry lab in a university, you’re not going to be able
to get accurate answers about the surface tension thing. I don’t
think for our purposes, however, that we need to be too concerned
with such things. I was merely pointing out that if you’ve got
sheeting, where previously you had the water beading up, then
there’s probably some detergent left on the surface, because pure
water has a specific surface tension and forms into droplets of water
and once the detergent is properly rinsed away, the water will revert
to beading again. Certain things affect that surface tension, one of
them being whatever detergent has been used. Pumice will also affect
it, as will differing surfaces of metal. A smoother surface will
promote beading of water, whereas a rougher surface will show less
beading. I’m sure others will know far more than me about
patination, but I’m sure the presence of a little detergent will not
be a problem.

Helen
UK

Sorry I forgot to mention that any beading previously seen may be
partly due to grease on the surface, which let’s face it, is what
we’re trying to eliminate. So while water does bead up by itself, due
to its own surface tension, it will not bead as readily on clean
metal as it will on grease. So it’s finding that balance between
getting rid of the grease and rinsing enough to eliminate the
detergent. It’s a judgement thing.

Helen
UK

I use Fast Orange...because it is in a pump bottle. It does have
detergent and pumice in suspension. 

Thanks, Richard! I’m going to look for Fast Orange, to see if it
works even better for me (and my etching class) than pumice and
water.

Judy Bjorkman, Owego, NY

Thanks to all of you for all of the great It is
apparent that there are many ways to reach the same goal. Today I
finished a new piece (brass), so I was ready to try getting it
“chemically clean”, or at least clean enough to make the patina go on
easily and evenly. I wanted to first try something that didn’t
require making any new purchases, just using stuff that was already
lying around the house. I first used hot water and dish detergent,
and “Barkeeper’s Friend” sink-scouring agent and a scrub brush.
Surprisingly, this did not produce sheeting of the water. I then
tried soaking for about a half hour in “Oxy-Clean”, which did produce
the water sheeting, even after being thoroughly rinsed. I then mixed
some liver of sulfur in hot water, and dipped the parts in, without
pickling first. This turned the brass a beautiful deep gold color
(previously, dipping in LOS did virtually nothing). Unfortunately,
that’s not the color I was after, but fortunately, after the brass
was dry, I tried dipping in hot sparex, and the color immediately
darkened. I left it in for a minute or two, and it was perfect, a
nice dark bronze-brown color. Next I want to get some gun bluing as
was suggested and see what it does.

Steve Shelby

http://shelbyvision.ganoksin.com/blogs/

1 Like

Helen and Jim, thanks for the on the nature of surface
tension. I’m disappointed that the “sheeting” test is not an absolute
indicator of metal cleanliness, but on the other hand, it explains
why some of my students who have done a good job of cleaning their
sheet metal still have water beading up on its surface.

Judy Bjorkman
Owego, NY

I'm disappointed that the "sheeting" test is not an absolute
indicator of metal cleanliness, but on the other hand, it explains
why some of my students who have done a good job of cleaning their
sheet metal still have water beading up on its surface. 

Yes it took me years to figure out that it was not a good indicator
because I assumed that the folks who said it was a good test for
cleanliness were right. In mokume it is imperative that the sheets be
clean to help with a good bond. I would scrub and scrub and then
still have beading or areas that would not hold the water as a
sheet. I finally started to look into it and found that sheeting is
not a reliable indicator. I have not found any foolproof method for
assessment of cleanliness but pumice and a little soap will provide a
good clean surface for most of what we need in jewelry.

Jim

James Binnion
James Binnion Metal Arts

If you warm the metal, the process happens faster. It can be set on
a hot brick that you just soldered on or on a hotplate. Handle the
metal by the edges.

marilyn

In mokume it is imperative that the sheets be clean to help with a
good bond. I would scrub and scrub and then still have beading or
areas that would not hold the water as a sheet. 

Just to point out, so people don’t drive themselves nuts. Even Jim’s
statement above is really saying “clean enough”. Clean is a relative
term, and perfection is never realistic if even possible. There is
clean, cleaner and cleanest, in reality. Truly “chemically clean”
would require a clean room and more technology than most of us have.
Clean enough or better is what we really are looking for, mostly.

Helen and Jim, thanks for the on the nature of surface
tension 

Glad to have been of help but sorry the disappointed.
However, although the sheeting of water isn’t a reliable indicator
of cleanliness, the presence of trace amounts of detergent and/or
pumice probably won’t hurt your patination process and the sheeting
more than likely still tells you that the patination will take effect
without it being patchy.

Helen
UK