silver soldering problem

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silver soldering problem

This topic has 18 replies, 9 voices, and was last updated 7 October 2013 at 13:26 by Baldric.

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22 September 2013 at 17:48 #15662
Baldric
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@baldric
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22 September 2013 at 17:48 #130449
Baldric
Participant
@baldric
I have been trying to do some silver soldering and can”t get to the solder to melt. The photo shows the part about 30 seconds after I gave up assuming the flux would have stopped working so I assume I got it hot enough, it was a bright orange colour. For seceral minutes, when I touched the silver solder on the metal it just woul not melt, but the heat coming off it was warming my fingers.
The silver solder was 455 with flux supplied by CuP as a starter kit. The torch is a Sievert 2491 and the material is mild steel 5/8″ diameter.
Can anyone tell me what I am doing wrong?
I have read advice on here and CuP”s site and thought I had followed it…..
22 September 2013 at 17:57 #130452
JasonB
Moderator
@jasonb
certainly way too hot you want just a dull glow. Flux has totally gone.

Did you mix the flux with water?

Try cleaning it all up, reflux and place a small bit of solder on teh joint which will melt an dflow into the joint as the right temp is reached.

J
22 September 2013 at 18:21 #130454
Baldric
Participant
@baldric
Jason, thanks for your reply.

The flux was mixed with a drop of washing up liquid and water. I did try the silver solder on the item at lower temperatures but it each time I put the rod on (1mm) it did not melt. I was expecting the rod to melt, and if the flux had gone it just to sit there and not flow. I did try this twice…

If I put a piece of solder on the 2 joints in this case I am not sure how to heat the part up without directly melting the solder with the torch, rather than having the joint melt the solder.

Baldric.
22 September 2013 at 18:26 #130456
Steve Withnell
Participant
@stevewithnell34426
Everything needs to be really clean before you start, then following Jason's line, make sure you are letting the heat flow to the joint, don't apply direct heat to the flux and solder. Mixing the flux with water ensures you get the flux right where you want it and no where else, so you get good control of where the solder is flowing.

If was looking to solder two strips of metal to form a "X" shape, I'd be putting the direct heat on one of the legs away from the centre of the X and letting the heat flow into the joint. Just a bit of patience and practice, that all.

Steve
22 September 2013 at 18:34 #130457
JasonB
Moderator
@jasonb
In a case like that its hard to avoid the usual advice not to heat the solder so just aim the heat at the largest piece of metal.

This part is a bit smaller at 1/8"x 3/8" section but the photo was taken 15-20 secs after the solder flowed and you can see its not as hot as yours.

And this one gives a good idea of how the flux should keep the joint area clean, this is 5/8" dia bar
22 September 2013 at 19:10 #130462
Keith Hale
Participant
@keithhale68713
Hi Baldric,

The alloy should have melted looking at the pictures – but may not have flowed.

Two totally different problems!

One part looks very hot , one is not.

You may need to use a different flux or modify your heating technique.

Ring us on 01909 547248 and talk it through. Help is at hand. You have not been abandoned!

Regards

keith
23 September 2013 at 08:15 #130495
Baldric
Participant
@baldric
Thanks for the replies.

Keith, I will probably not be able to call until Friday. The cooler part is the second joint, towards the top of the picture the two parts (rod at 90 degrees) are both at the same temperature. I guess part of my problem was that in an effort to avoid taking to long to heat the parts thus use the flux I heated up to much and used the flux that way instead.
23 September 2013 at 15:00 #130535
Sub Mandrel
Participant
@submandrel
Are you using enough flux in the first place?

When I silbver sodler there seems to be flux everywhere…

Neil
23 September 2013 at 15:30 #130538
Michael Kilpatrick 1
Participant
@michaelkilpatrick1
Also heat your rod and dip it in the flux powder so it has flux stuck too it, never heard of adding washing up liquid to flux paste so forget that, just mix to a paste as instructed above.

Mike
23 September 2013 at 15:49 #130542
Baldric
Participant
@baldric
Posted by Michael Kilpatrick 1 on 23/09/2013 15:30:01:

Also heat your rod and dip it in the flux powder so it has flux stuck too it, never heard of adding washing up liquid to flux paste so forget that, just mix to a paste as instructed above.

Mike

Mike,

The adding of detergent and not dipping the rod in flux are both things that CuP alloys website mention, see **LINK**

Neil I suspect you are right having looked at a couple of on-line videos now, I had put it where I wanted the solder to flow, i.e. in the joint, the videos seem to show a liberal covering in the whole area.

Baldric
23 September 2013 at 16:07 #130543
JasonB
Moderator
@jasonb
Yes you need some around the outside, look at the second picture I posted above, the grey areas are where the flux was, the black where it did not cover.

A drop of Washingup liquid does no harm and is quite common practice. Best not to heat the rod and dip in flux, you should have the flux on the job not the rod.

J
23 September 2013 at 17:05 #130544
Sub Mandrel
Participant
@submandrel
The washing up liquid helps the flux paste wet the work, so it doesn't just run off. The 'Hot rodding' with flux on the silver solder CuP deprecate is a risky technique where no other flux is used.

Neil
24 September 2013 at 07:49 #130581
Keith Hale
Participant
@keithhale68713
Why add a few drops of washing up liquid to powder flux prior to mixing with water?

a) it aids mixing to a smooth paste

b) it makes the flux stick to the work

c) when the paste dries out (and it will) it can be remixed with a few drops of water – the alternative to throwing it away

Problem that can arise with "hot-rodding" include

a) insufficient flux leading to poor coverage –

b) it promotes a welding technique for heating – poor penetration of alloy

c) the flux is not active enough quickly enough for efficient oxide removal. Factory made flux coated rods have a modified flux to cope.

For more information see "Best Brazing Practice" on website

**LINK**

regards

keith

regards

keith

Edited By CuP Alloys 1 on 24/09/2013 07:52:18
24 September 2013 at 13:52 #130598
Bob Perkins
Participant
@bobperkins67044
Hi Keith

thanks for the link to the website, it's been helpful reading through the info. I'll try the washing up liquid next time I mix up a flux paste. A couple of questions you may be able to answer for me:

Intend to discard unused flux paste when I've finished. To be honest I never mix up too much, so don't end up throwing away a lot. Am I right in thinking that this can be revived at a later date with a bit of water? If yes, how long will it remain re-useable, hours, days, weeks?

your web site says "Do not use conventional firebricks eg from storage heaters". I'm using some log burner hearth bricks for my hearth. Are these suitable or will they retain Instead of reflect heat?

Thanks for your input . As a newbie I'm finding this really interesting, and have over the past few months overcome some of the issues Baldric is experiencing
24 September 2013 at 14:07 #130600
KWIL
Participant
@kwil
Bob, As has been said before, Thermalite building blocks are a cheap reflecting work surface for silver soldering etc, throw them away when damaged beyond use.
24 September 2013 at 14:09 #130601
Gordon Wass
Participant
@gordonwass
As a beginner at silver soldering I followed CUP's advice and was very pleased with results. But if I can add a couple of things – Flux seems to last several months after it has dried out. I found using meths instead of water helps , especially with delicate jobs, less bubbling. I use stove bricks also, good enough for small jobs but the proper bricks will be better for big jobs.
24 September 2013 at 18:47 #130614
Keith Hale
Participant
@keithhale68713
Hi Bob,

Log burner hearth bricks – fine!

The flux paste we use for brazing demos at exhibitions was made up 8-9 years ago! We just add a few drops of water on day one. It is getting a little low now so we will be making up a small batch soon to take us up to 2025.

Hi Gordon,

Spot on.

Meths = less bubbling and no need to add washing up liquid.

regards

keith
7 October 2013 at 13:26 #131926
Baldric
Participant
@baldric
Thanks to CuP who were happy to talk through the issue I had, I have no completed the task, I placed the solder in the joint and heated the unit until the solder melted, it then flowed nicely.

I did do an experiment with a thin piece of strip steel to see what happens to the flux as it heats up, and then managed to melt solder on this direct from the rod using the heat from the steel not the torch, I think I need to practice more perfecting each technique as I need it.

Baldric.
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