Hi Charles,
Of course if anyone knows a product in Australia that has a large percentage of boric acid in it's make up, please let me know
I don’t know if you can get cockroach poison or not in OZ, but in
the US it’s almost 100% boric acid.
Dave
Leonid,
Bring joint to red heat using reducing flame.
A reducing flame; that’s something I didn’t know; I was using a blue
high oxygen flame.
That would explain some of the problems with oxidation I was having.
Tell me what type of torch and fuel combination that you are
describing for soldering copper.
George
Vancouver Island
Australia has about 400 species of cockroaches. Finding the most
common control agent ( boric acid) shouldn’t be difficult.
http://www.greenharvest.com.au/fact_sheets/fs_cockroach.html
jesse
1 Like
I don't know if you can get cockroach poison or not in OZ, but in the US it's almost 100% boric acid.
I looked at those, but nothing yet, the chemicals in the brands I’ve
checked here make the hairs on the back of my neck stand up.
I’ve got a few leads now, so I send my thanks 
Regards Charles A.
I get my powdered boric acid from the local Walmart pharmacy. I have
to order it, but it comes in a day or two. I think my last order was
about $10 for 2 one pound jars. That was in September this year. In
any case, it didn’t seem like a lot of money and the pharmacy is
local so no shipping charge.
As I remember, boric acid in a weak solution was used at one time to
rinse the eyes of newborns.
I just googled boric acid sources and found both boric acid crystals
and boric acid powder available from soapgoods.com for about $4 for
a pound. So it appears that if you think of it as a household
chemical, it is readily available. I also noticed that they have
borax in multiple forms.
And if you look at your jewelry equipment supplier, you can find 5
pound boxes of the stuff for $15.
Judy Hoch
That would explain some of the problems with oxidation I was having. Tell me what type of torch and fuel combination that you are describing for soldering copper.
oxygen/propane. Even if you are using plumbers torch, there will be
an area of flame envelope with reducing characteristic. To find such
area - vary the distance between torch and metal and observe the
effect it has on the metal.
Leonid Surpin
Bring joint to red heat using reducing flame
Leonid; What is a reducing flame? I understand it is oxygen rich, but
how would I achieve that using an acetylene air torch? Also, by “rod
form” of solder do you mean the wire that is commonly available, and
would you suggestusing hard or medium? Do you think that multi-stage
soldering could be done with a progression of hard through soft?
Thanks for your help, Mary
House of Jewellry in Brisbane or Sydney sells Boric Acid powder in
450 gram containers. I got my last container at their Brisbane shop
so I imagine that they stock it all the time.
Nick
What is a reducing flame? I understand it is oxygen rich, but how would I achieve that using an acetylene air torch?
Actually it is the other way around.
Any kind of burning is a subset of reactions of oxidation. It is the
same process as rusting of iron. The difference is that some
substances like propane, acetylene, and others when combine with
oxygen produce so much heat that flame is the result.
There are only 3 possibilities of combining oxygen and flammable
gas. If the amount of oxygen is exactly what is needed to oxidize gas
completely, without any residue. That is called neutral flame. To
achieve it - ignite gas and start adding oxygen little by little,
until all presence of yellow have disappeared and inside cone is blue
and well defined, but not overly tight.
There is more oxygen than needed to oxidize the gas. Resulting flame
knows as oxidizing flame. It is the hottest type of flame, because
excess of oxygen allows for very fast burning. Very limited use but
sometimes indispensable. To achieve it - proceed as in neutral flame,
but keep adding oxygen until inside cone is very sharp, very tight,
and intensely bright blue. Experienced welders know how much to open
both valves before igniting to go straight into required type of
flame.
If there is less oxygen that need to oxidize gas completely, such
flame is called reducing. The reason for the name is - if such flame
is passed over metal oxides, the excess of flammable gas combines
with oxygen component of oxides and leave the pure metal behind.
Copper gets black when heated because copper reacts with oxygen in
the air and forms copper oxide. Reducing flame restores oxide to it’s
metal state. In chemistry such process calls “reduction” and
therefore the name for this type of flame. To achieve it - stop
adding oxygen before all yellow disappears from flame.
Many types of reducing flames are available and it is very useful to
experiment to understand their uses. In general the more yellow in
the flame, the colder it is.
Any flame have different zones where flame characteristics are not
well defined. Such zones can also be useful for different soldering
situations. They are found by varying the distance between torch and
a piece. There are much more can be said about the subject, so I
encourage to read about reaction of burning and flame structures. I
cannot point out to any particular book, but start with basic
chemistry textbook discussing reaction of burning. I believe Brepohl
in “Theory and Practice of Goldsmithing” talks about it somewhat.
Also, by "rod form" of solder do you mean the wire that is commonly available, and would you suggestusing hard or medium?
Yes, rod mean stiff wire. It can be round, but it is always good
idea to roll it down to the thickness of metal been soldered. Always
use hard solder. With proper flame control, one can construct a piece
of thousand joints with one type of solder. Medium solder should be
reserved only to situations where hard cannot be used. But resist
temptation for as much and as long as you can. Develop your soldering
skills and you will amaze yourself with what can be done with hard
solder alone.
Easy solders do not belong in manufacturing process and should be
reserved for repairs only. If you find yourself in situation where
you must use easy solder, something gone wrong in your planning or
designing stage.
Leonid Surpin
1 Like
Many types of reducing flames are available and it is very useful to experiment to understand their uses. In general the more yellow in the flame, the colder it is.
When soldering copper with a reducing flame, at the correct distance
to the piece, will the oxidation of the copper stop completely? Is
flux on the copper pieces required; or just on the solder. Does a
reducing flame take a long time to heat copper to the hard soldering
temperature?
George
Vancouver Island
If you are using an oxy propane torch first light the torch with just
propane and then open the oxygen valve until the inner cone of the
flame is a pale blue colour and has a slightly ragged edge. There
will be tinges of orange and yellow in the outer flame. If the inner
cone is bright blue and hard edged and the torch makes a sharp
hissing sound then you have an oxidising flame so back off the
oxygen or increase the propane to get a reducing flame. You may have
to tweak your adjustments a few times until you have the size flame
you want and a stable correct gas mixture. Just make sure the flame
is right before putting it anywhere near your job and keep an eye on
the flame. I know my torch sometimes takes a minute or so to settle
down.
All the best,
Jenny
Leonid-thanks you for explaining the different types of flames. Are
you referring to an acetylene oxygen tank? I use acetylene air which
does not allow me to control the amount of oxygen by opening a
separate regulator. My question is then how can I produce different
flame types with the acetylene air tank, which uses the air in the
atmosphere? If this is not possible is do you suggest I use a larger
torch tip and make the flame large, using a particular part of the
flame? Also, how would I roll down the wire thickness? I do not have
special equipment as I have a small home studio.
Mary
When soldering copper with a reducing flame, at the correct distance to the piece, will the oxidation of the copper stop completely? Is flux on the copper pieces required; or just on the solder. Does a reducing flame take a long time to heat copper to the hard soldering temperature?
The best way to understand this is to take a torch and start
experimenting. For reduction to take place, one needs right flame
and right temperature. Start heating copper. First you should see
rainbow colors on the metal. Than it will go black, and than you
should notice that if yellow part of the flame in contact with metal,
the oxide is gone. There is no need for flux on the metal. When metal
looks clean, touch joint with rod dipped in flux. Flux will melt and
flow into joint. With your thumb, add oxygen to the mixture to form
a neutral cone and bring tip of the cone to the joint. Solder should
flow very easily.
Reducing flame is colder than other types. Very yellow flame is
colder than slightly yellow flame. But it will be a mistake to think
that flame temperature is the deciding factor. Amount of heat
produced by the torch is much more important than flame temperature.
Copper present special problems because it requires large amount of
heat and heat spreads very evenly. So to reach required temperature
at joint, without forming oxides is difficult. Reducing flame solves
this problem. If torch is very large, soldering can be accomplished
with reducing flame alone. Our ancestors did it on bed of charcoal.
With smaller torches, one should switch into neutral flame to finish
the process.
A word of warning. Do not use this technique on silver, unless it is
95% pure or higher. Sterling will be destroyed by this technique.
Other silver alloys so popular these days, I have no idea. Some gold
alloys will be ok, and others will not.
Leonid Surpin
I use acetylene air which does not allow me to control the amount of oxygen by opening a separate regulator. My question is then how can I produce different flame types with the acetylene air tank, which uses the air in the atmosphere?
It is still possible to a degree. Those type of torches designed to
mix air and fuel with maximum efficiency to give use neutral flame.
But it only happens at the tip of the cone. Outside of the cone flame
is oxidizing, because more air is available, and inside the cone
flame is reducing because acetylene dominates. By varying acetylene
flow, one varies intensity of the flame and by varying the distance
to metal, one selects which part of the flame to use.
If this is not possible is do you suggest I use a larger torch tip and make the flame large, using a particular part of the flame?
Always use the largest torch that you can control.
Also, how would I roll down the wire thickness? I do not have special equipment as I have a small home studio.
You can flatten it with hammer. A lot of recommendations describe
ideal conditions. That does not mean if conditions are not ideal, it
would be impossible to do. In goldsmithing we rarely have everything
in our favor, so one needs to improvise and do with what is
available. That’s how we like it, would not have it any other way. I
always say, think about how it was couple of centuries ago. As
limited as you think your resources are, a goldsmith of middle ages
would give his right arm for it. A lot of great work have been done
with less.
Leonid Surpin
Mary,
I use acetylene air which does not allow me to control the amount of oxygen by opening a separate regulator.
My acetylene air torch has big holes in the tip, near the handle.
Quick and dirty… a thumb covering a hole = reducing flame. Tape
also works well or get really fancy with a thin metal collar to
cover the air inlets.
jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand
I am using a small butane torch. I can adjust the flame somewhat,
but not anything like with an oxy-acetylene set up. I get a lot of
oxidation on my copper and find I have to heat it a long time in
order to get the solder to melt and for two metals to stick together.
Is there a way to reduce the amount of oxidation I am getting with my
small butane torch?
Claire in TN
Is there a way to reduce the amount of oxidation I am getting with my small butane torch?
The best solution is to get a plumbers torch. Small torch just does
not produce enough heat for copper soldering.
Leonid Surpin
I recently soldered copper to copper with a propane/oxygen torch and
ended up with lots of beautiful cherry red oxidation. I had an awful
time getting the two pieces to solder using silver solder. What am I
doing wrong? I know from a recent workshop that the red can be used
as a decorative touch but that’s not what I’m after when I’m
soldering.
Thanks.
Barbara Jacquin