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Propane canister (plumber's torch) problems


#1

I’ve read so often that a simple plumber’s propane torch (mine is an
Ace hardware variety) is more than adequate for soldering bezels onto
sterling sheet. I’ve got a fairly large piece of sterling, and have
been experimenting all day without success. I’m wondering if I’m
doing something wrong, or if I’m asking more of this torch than it
can deliver.

The sterling sheet is 20 gauge, 65 mm x 50 mm. The bezel is oval,
about 50mm x 35mm. I’m using Pripp’s and have tried both medium and
easy solder. I’ve tried heating from beneath by 1) supporting the
sheet on two 1" high pieces of kiln brick; 2) supporting the sheet on
two pieces of coat hanger; 3) suspending it with a third hand. I’ve
also tried resting it directly on the brick and heating from above.
I’ve tried a small flame and a large flame. The sheet just doesn’t
seem to want to get hot enough – there’s no color change.

The other day, I did successfully solder a small bezel on the same
size sheet by supporting the sheet on the two small pieces of kiln
brick. In that case, most of the sheet could rest on the brick pieces
and the only real air space was directly beneath the bezel. The
silver reddened up nicely. With this large bezel, only the very edges
of the sheet can rest on the brick pieces, and there’s a large air
space. As you can see from my experiments, I’ve tried changing the
size of the airspace by having the sheet at different heights.

So, do you think there just isn’t enough oomph in the torch to
handle such a large bezel, or can you suggest a better way to support
it, or I am doing something radically stupid somewhere?

I’ve thought of cutting away a large section of sheet inside the
bezel to reduce the mass of the silver, though I’m not thrilled about
the aesthetics of that.

Thanks for your help!


#2

It may be you don’t have the right tip. You need one that has a
flame with a defined blue to yellow cone. Most of the torches that
you get in the hardware store have a more broad, brushy flame. If
that is not the problem, get another torch and use both of them at
the same time. Also make sure your metal is really clean. Your best
be though is to get a Presto lite with an acetelyne tank.

Jerry in Kodiak


#3
I've read so often that a simple plumber's propane torch (mine is
an Ace hardware variety) is more than adequate for soldering bezels
onto sterling sheet. 

I used one of those torches for years and in my experience you should
be able to do the piece you’ve described. I’ve used Hard grade solder
on brass and silver buckles about the size you’ve described and while
it’s not a trivial exercise --that type of torch obviously has it’s
limitations-- it certainly can be done.

As you’ve surmised the main problem is getting enough heat into your
piece for it to reach soldering temps.

Simply stated you need all the help you can get. Open-air setups like
the third hand aren’t going to do it because so much of your heat is
being whisked away by the surrounding air. If it were me I would set
up a “mini-kiln” arrangement where three firebricks meet, as if to
form the the bottom corner of a box. Elevate the workpiece slightly,
say 1/4 inch off the surface of the bottom brick so that the flame
can get underneath. Make sure there is a little space all around the
workpiece so that the flames can get in and around the whole thing
(you don’t want trapped or dead air). The idea is that you’re
creating a semi-enclosed space that you can pump heat into instead of
losing it to the surrounding air.

Keep your torch in motion to bath the workpiece in flame. By keeping
a careful eye on the colors --dim the lights if you need to-- you can
see where the “sweet spots” are for positioning your flame and which
spots are less efficient. Be flexible, go with what’s working, but be
determined too because you’ve just got to pump the heat in until
everything comes up to temperature.

You might also consider using a charcoal block to set the workpiece
on. They heat up nicely and can help get heat into the bottom of
your setup.

Also, consider a second torch. When I was doing large pieces like
this I had a second propane torch on standby, just in case I simply
needed to pour in more heat. Yes, this is cumbersome and all the rest
of it … but I’m wearing the buckles I made using these techniques
so it can work.

For reference my buckles were as heavy as 14 gauge, often 60 grams or
more in total weight.

One last thing: it’s probably going to take you a while to get enough
heat into the piece for everything to flow nicely. Watch your flux
to make sure it hasn’t all burned off by the time things get hot
enough. If it has then try using more. If that still doesn’t do it
then consider using a more robust flux, one that can stand a little
more torch time. Don’t forget good old plain borax as a helper for
the job. The gods were smiling on silversmiths the day they gave us
borax.

Cheers,
Trevor F.
in The City of Light


#4

I used a “Bernzomatic” style – plumbers’ torch-- w/ a flexible hose
for a couple years when I had my first studio and was able to
accomplish quite a lot. Your project sizes don’t seem out of line…

What’s exactly happening? Is the solder flowing or melting at all?
Is the flux burned away?

Andy


#5

Regarding a large bezel on sheet with a propane torch: In the years I
used hand-held propane and did large bezels, I used one above and one
below. It helps to have a buddy nearby to circulate one torch but it
can be done alone. Your problem may be keeping the sheet surface hot
enough for the solder to flow evenly. Its doable,
though. Persevere…silverp in Florida


#6

Another issue I’ve run into as I still use various propane/natural
air torches, not all so called “propane” is the same. A propane
dealer I used to get forklift fuel from explained that all propanes
are mixtures of propane, butane, and other hydrocarbons. One reason
is the freesing point of pure propane, (around 40-45 degrees F. if I
recall), so some % butane takes the freezing point down well below
zero.

At one time I had a chart that compared the total BTU content of
several of the small portable tanks. As I recall, Colmane and
Benzomatic were around the highest BTU ratings. Store brands, had
varing BTU amounts down to nearly 1/2 the total BTU of the best
brands.

So, if you’ve recently changed tanks/brands try another brand of
commercial fuel. By the way, some say, it’s most accurate to call
this stuff LP or Liquified Petroleum, or Low Preasure (which it’s
not realy all that low!).

Keep experimenting and have much fun.
Hope this helps,
Ed


#7

That is a fairly large piece if I am looking at the metric side of
my ruler right. If you have ceramic bricks, you could build a three
sided wall around the silver and even partially cover the top. I
haven’t really used the hardware store propane torches but I suspect
that you need more heat for what you are truing to do. It will be
harder to keep that flame moving over the piece but do not let it
stay on just one part of the silver. Keep it moving. Very tiny
pieces of solder will melt faster. Use a white paste flux, it will
stay active longer.

marilyn smith


#8

problem with propane bottles? tilt forward and your flame will gas
out, liquid instead of gas! better way? Get hose that connects from
your torch handle to the bottle and attach bottle to something
stable. You can then cotrol your flame and less wieght makes for
easier torch motion.

Ringman


#9

I learned to solder silver jewelry with a plumber’s torch. I mean
the kind with the big ol’ nozzle on the end, not a pencil tip.
Here’s what I learned over the years I was using propane.

Silver is an excellent conductor of heat so a large piece of silver
will always be cooling itself off if the heat isn’t great enough
over the entire piece. Propane usually isn’t up to the job for large
masses of silver. It simply doesn’t burn hot enough.

Try using Mapp gas. It’s hotter athough a bit dirtier but not enough
to matter. It’s available wherever propane is avaiable.

Susan H. Maxon
Honors Gran Jewelry
Palm Harbor, Florida
727-736-1990


#10
   I learned to solder silver jewelry with a plumber's torch.  I
mean the kind with the big ol' nozzle on the end, not a pencil tip.
Here's what I learned over the years I was using propane. 

For thart matter not too many years ago the Navajo used the old
gasoline blowtorches and did great work with them, but the finer
flame is much better.

Jerry in Kodiak


#11

Thank you all so much for your suggestions. I’m going to try pretty
much every idea you’ve offered and will post the results, just in
case someone else down the line gets stuck in the same place. It’ll
take a little time to acquire some of the extra items, though.

Andy, no the solder isn’t melting at all. The silver sheet doesn’t
change color, just stays dull and lifeless.

Jerry, you’re right about the flame. The one that comes with the
torch is quite bushy, and instead of one cone, there seem to be
several (haven’t counted). I’ll investigate a different tip.

Trevor and Marilyn, I’m eager to try the mini-kiln approach. It
would be cost effective, and probably the safest method for me.

Ed, I’m using Ace’s brand of propane. It’ll be interesting to see
how Coleman and Bernzomatic will compare. I never knew there might be
a difference.

Pat and Trevor, I hope I don’t have to resort to two torches! It
took me several months to work up the courage to use ONE in my house,
and my husband is still uneasy about it.

Again, thanks so much. This was my first posting to Orchid, and
you’ve all been so kind.

Regards,
Diane


#12
    you're right about the flame. The one that comes with the torch
is quite bushy, and instead of one cone, there seem to be several
(haven't counted). I'll investigate a different tip. 

There is also the possibility that there is some debris in the
little holes in the torch head preventing the formation of a smooth
pencil type flame. There are professional plumbers torches which have
a much hotter flame due to the forceful mixing of air and propane.
They usually have names like, Swirljet or Turbotorch etc. The
drawback is that there is so much force to the flame that it will
push small pieces away and you would need to heat from underneath.
You will find these available at a Plumbing supply house. Most every
wholesale supply house always has them on display at the counter. If
you go in and approach the counter they will probably sell tools to
you and charge tax or you could use your resale liscense.

Dan Wellman


#13

I use the same torch. At times it just won’t get hot enough.
That’s when I take the nozzle apart and evict the spiders. Some
spiders love the smell of propane and try to get to the source.
Their only route of course is via the nozzle. They’ll leave webs in
the nozzle…


#14

I’d like to report on an experiment, thank you all, and finally
announce success!

First, the piece of silver that was problematical apparently really
is too much for a propane canister torch using normal techniques. Dan
Ice (20 something years experience) kindly set up an experiment with
pretty much the same parameters and found that the silver didn’t
heat. Below are his comments:

 Sterling 20 gauge sheet 52 mm x 69 mm.  Fine silver bezel 38 mm x
52 mm. Dandix flux. Easy solder snippets. First I tried the
canister of propane I had here from a couple of years ago. Brand
"Spitfire".  Back heated for 8 minutes and nothing was happening. 
It got to approximately 900-1000 degrees by color of stuff in the
flux. I next cleaned and pickled, refluxed and tried again.  6
minutes. Nothing. I then went out a bought a canister of
Bernzomatic.  Back heated for 10 minutes.  Approximately 1100
degrees by color of the metal from about 6 minutes on to 10
minutes.  Nothing happened. I then tried my Little Torch
Oxy/Acetylene with the number 5 tip. Flame about 3.5 inches long. 
Solder flowed nicely at between .5 and 1 minutes.  I do know that I
have kept heat on a piece for as much as 4 or 5 minutes when doing
a big overlay, so patience is sometimes quite necessary.
Conclusion.  Probably not enough overall heat for that big a piece
from the propane torch.  I don't know what propane alone gets to
for temperature. Oxy/Acetylene reaches 3,000 degrees. Undoubtedly
the problem was just plain not enough heat buildup. 

Before going out and paying for shop time, I decided to the
mini-kiln approach. I bought two magnesia blocks, sawed them in half
lengthwise, and used them to create walls on three sides, as well as
partially covering the top. I rested the sheet on two pieces of bent
coat hanger. That did the trick! Solder flowed easily within a
minute. The “roof” made it a little awkward to get heat to the back
side, so it was necessary to stop and rotate the sheet.

Thank you all so much!

Diane