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Member postings for CuP Alloys 1

Here is a list of all the postings CuP Alloys 1 has made in our forums. Click on a thread name to jump to the thread.

24/06/2017 07:56:44
Silverflo 452 is a 45% silver cadmium free alloy with 2% tin. It will produce strong joints but it behaves nothing like easiflo 2. It has a higher melting point and is not as fluid. Like anyone else who struggles with a cadmium free alloy fit a larger burner.
Thread: Help with Propane torch please
17/06/2017 18:39:08

Hello John.

I trust your local plumbing merchant was helpful!

I am told by Sievert that the burner thread is M20 x 1.

It is not a unique thread.



16/06/2017 07:54:18

Hello John,

Sievert have made some changes over the years but, as far as I understand, they have not related to the burner thread. The modifications have been at the other end of the torch.

For details of sievert burners visit **LINK**

They are normally available ex-stock


Thread: Silver Soldering Inverness or Elgin way
02/06/2017 12:34:58

Hello Michael

Re Thesscal A I fear it is a sad end.

Conversations with contacts within the trade, including the manufacturer of Thesscal A have confirmed my thoughts that it is no longer available.

If there is a need to soft solder aluminium or its alloys use the apprropiate soft solder flux with any soft solder. If a decent colour match is required use a silver tin alloy.

All products are readily available but save about £12 on the flux by ordering it for collection at an exhibition. Te delivery costs are very high as it cannot be sent by post.



31/05/2017 09:48:02

And finally,

Melting point of pure (99.99%) aluminium is660 deg C. Melting point of commercially pure (99.5%) i 635 deg C. Alloyed this can reduce further to 500 deg. Lowest melting point silver solder was 620 deg C (Now banned fpr sale) Currently the lowest is 652 deg C (56% silver).

How good is your heating technique ?smiley

Any soft solder can be used to solder aluminium. You only need the right flux. It is expensive to deliver. Visit the CuP Alloys Roadshow or get it at an exhibition. The savings will easily cover your entrance fee.

If the aluminium content of your bronze is higher than 2% but lower than 10% tweek your flux. Add 25% by weight of kitchen salt to your standard flux. When mixed with water into your paste, the extra chloride ions will remove the aluminium oxide, Alternatively buy a speciality flux and that is an expensive way to buy salt.

The search is on for a filler metal that melts about 450 deg C. Probably based on tin, copper zinc antimony alloy or whatever it will be an overnight winner guaranteeing the patent holder a fortune. As long of course that it is not as brittle as carrot!!

By the way, note that the link to the silver solder is for rods that are only 250 mm long!

The industry norm is 500mm so it is not a true comparison.




Edited By CuP Alloys 1 on 31/05/2017 09:51:50

Edited By CuP Alloys 1 on 31/05/2017 09:52:26

Edited By CuP Alloys 1 on 31/05/2017 10:10:05

Thread: CuP Alloys Roadshow in Scotland?
30/05/2017 10:40:05

We have been aware for a long time that we haven't done an promotional work in Scotland.

We have been singularly unsuccessful in finding an exhibition venue. Where do you visit or are you content to travel to Doncaster?

We are looking into bringing the roadshow to Scotland. The proposed plan is to attend an exhibition over a weekend and visit societies a few days either side of the exhibition with the talk aimed at brazing successfully.

What are the basic principles.? How do I achieve them?

Hopefully we can amortize the costs making it economically viable to the societies.

Your help and ideas to make this a success is requested..Is your society interested in a talk?

Get sound technical help from the number one supplier of brazing materials to the model engineer.

Please contact Shaun on 01909 547248 or



Thread: Silver Soldering Inverness or Elgin way
30/05/2017 08:55:49
Posted by Neil Wyatt on 29/05/2017 11:06:11:.

Yep, silver soldering becomes 'alloying' when attempted with aluminium



29/05/2017 10:03:32

Hi Carl

Two thoughts.


get to understand the principle of silver soldering - capilllary flow.What to do, why and how. Visit **LINK**

There is a short video clip to help you.


there is a separate video going into more detail about the principles and how it relates to boiler manufacture. The best of both worlds. Good technical advice and a demo from a true professional Helen Stait of Western Steam.

But for help at any time call us on 01909 547248



Thread: boiler leak
19/04/2017 13:15:29

Firstly that's good advice from Simon.

Secondly that good friend should not try to fix each leak in isolation. The whole area needs to be taken up to temperature. This will avoid any thermal stress caused by localized expansion. You have got three poor joints. It is possible that there are other weak joints caused by poor alloy penetration into the joints. This stress could quite easily cause other joints to fail and you end up on a merry-go-round chasing the next leak.!

You may need to use two torches. One, a propane torch to get the background heat in and oxy/something for the final lift to brazing temperature and create the necessary heat pattern to promote the capillary flow of filler to where you want it. The leaks at the firebox end may require the use of a cyclone propane that will stay lit in the confined spaces.

A ceramic blanket will help to get, and keep, heat n.

Yes use 455 alloy with 55% silver.

Use also HT5 flux to give you a good flux life and use plenty of it to clean the joints and protect the others.

Almost forgot ....... then allow to cool naturally



PS It's my guess that the boiler was originally put together with oxy/acetylene only and the basic principles of the brazing process not followed

Edited By CuP Alloys 1 on 19/04/2017 13:35:57

Thread: Braze or screw cut - which is stronger?
05/04/2017 07:26:41

Hi Andrew,

For more info on brazing go to **LINK**

Read it - load your printer - print it - and read again. Keep it by you. It will set you on your way to successful brazing with a clear understanding of what to do, why you have to do it and how to do it.

Do it right and the joint will be stronger than the parent materials,

You may not elect to use silver solder as your filler metal but a brass rod instead. No matter, the principles are identical. You are still brazing.

If you require any further help, then come back to us.


Thread: soldering stainless steel to copper
01/04/2017 08:02:11

Hello Roger

If you require only a small quantity use a suitably flux cored wire e.g. 2207.

A flux specifically for soldering stainless steel can be sent in the post.

2207 is a silver tin alloy with excellent flow characteristics to produce strong leak-tight joint with small neat fillets

It will also give a good colour match on your stainless.

It is readily available

For more info **LINK**



Thread: Silver soldering
17/03/2017 10:18:18


OK it does not require a flux on copper to copper joints.

OK it is cheaper than silver solder. If price is what floats your boat use a similar alloy but without any silver. Joint ductilitystrength is not compromised

You also get something else.

A hot sulphur bearing atmosphere above 200 deg C (like that produced from a coal fired boiler!) will go through the joint like a hot knife through butter. And there is no repairing it.





15/03/2017 10:36:00

For more information on all topics related to silver soldering/brazing visit




Thanks Neil

Edited By CuP Alloys 1 on 15/03/2017 10:37:30

13/03/2017 11:41:50 Henry,

If you are having difficulty you are probably not sticking to the overall principle of silver soldering - the use of capillary flow to efect the joint.

There is cleanliness of the joint and correct heating.

Cleanliness at brazing temperature is the important bit. That is achieved by using the right flux Use a flux that matches your heating time and melting range of your alloy. If your silver solder simply melts and goes into a ball you have a flux problem. Simple. There is enough heat to melt the alloy so that is not a problem.

Initially use a conventional low temp flux. Mix to a paste and apply liberally to the joint. Then apply the heat. BE PATIENT. Wait until the flux melts and turns into a clear liquid. The flux isnow working. The flux also tells you that you have achieved brazing temperature. NOW APPLY THE ROD TO THE JOINT.

If you are not melting the flux. You simply need more heat. Fit a bigger burner and burn more gas.

Alternatively, if it is taking a while to get the joint hot enough, the flux may be becoming exhausted. A liberal covering can help or alternatively use a longer life flux eg HT5. It too melts nto a clear liquid as you achieve brazing temperature but protects the joint longer.

Please do not use borax as a flux with cadmium bearing silver solder. It only starts to work at higher temperature resulting in the overheating the alloy with the increased evolution of toxic cadmium metal fume.

In essence either change your burner or change your flux.

For more information go to



Edited By CuP Alloys 1 on 13/03/2017 12:07:24

Edited By CuP Alloys 1 on 13/03/2017 12:13:15

Thread: Brazing
10/03/2017 10:55:15


Sievert regulators cannot be opened to the point that they do not regulate the presuure of gas being fed to a burner.

Regulator 3091 is a "fixed" regulator factory set to deliver 2 bar.

Regulator 3063 is a " variable" regulator that can be adjusted manually to deliver between 1 - 4 bar

Regulator DN20056X is a variable regulator that can be manually adjusted between 0 - 4 bar.


The 3000 range of burners is designed to run at 2 bar

The 2000 range is designed to run at between 2 and 4 bar dependent on the heating effect required. Increased pressure = increased heat output.

Trying to run a 2000 burner at 4 bar results in the flame being blown off the end of the burner. Trying to reduce the heating effect of a 2000 series burner by reducing the presure below 2 bar causes the flame to withdraw into the nozzle. This can damage the injector not least by causing it to block with the soot formed by incomplete combustion of the gas.


08/03/2017 23:32:00
Alan. If your torch is flaming out there are two possible reasons. The gas pressure is too high and the speed of the gas flow is exceeding the speed at which the gas burns. You could be simply blowing the flame off the end of the burner.
Or you are starving the gas of air. In this case change the burner to a cyclone type.
For more information see the website
Thread: Silver Soldering Long Sections
02/03/2017 07:19:12

You weld with TIG. You do not braze.

They are two totally different processes. Silver soldering is just one facet of the brazing process that is dependent on capillary flow to effect a joint. Heat from a TIG torch is more intense than oxy-acetylene, It is highly unlikely that you will be able to generate the heat in the right places to make a successful joint. It is bad enough with oxy-acetylene. This is the main reason model engineers have joint problems. At best you will simply melt the silver solder on top of the joint leaving a crack underneath!

You are not brazing You are not welding. You are simply using an expensive rod to block a hole! Probably the reason Andy didn't make it work.

48 years in this business and I've never seen TIG as a heat source for brazing work either! I can't even recall it being attempted.

It has nothing to do with contamination, nor the alloy used - special or not. Joints attempted using TIG will be inferior if made at all,

Going back to the original question, if there is still too much distortion when using tin-lead paint/paste/wire then glue it!


01/03/2017 20:39:43

Hello Richard

Soft solder it with 60/40 tin lead soft solder> Melts at 187 deg

25% of the distortion problem compared to silversolder.

Joint strength I suspect will be adequate.

This is one of those occasions when silver solder is not the answer!



Edited By CuP Alloys 1 on 01/03/2017 20:45:17

Thread: Silver Solder Stocks
09/02/2017 07:48:06


1) The re-melt temperature of easi-flo2 is higher than the original.

2) Even if it melts ,Easi-flo 2 is totally compatible with 455. 455 will repair any leaks.

3) Any molten silver solder will be retained in the joint gap by capillary action (the fundamental principle behind the process). Ensure a good coverage of flux to prevent oxidation and dewetting of the alloy = another leak. Use HT5 flux.


I suggest to anyone struggllng with Silverflo 24 as the first alloy in a step-brazing operation to simply switch to a lower melting point alloy like 438. 438 and 455 work together well.

For more information go to **LINK**


Keith (Hale - no relation to Phil!)

08/02/2017 14:50:12

As Rod explained, you just need more heat. His approach is spot on. Possibly use a bigger burner and insulation to keep the heat in. You may need a longer life flux like HT5

Watch the flux. When it has melted and started to flow apply the alloy. It is pointless trying to braze until the flux has melted. The joint is simply not hot enough. Do not heat the alloy. Allow it to get its' heat from the joint. Getting the alloy hot is one hing - getting the joint hot enough is another. If the joint is cold the alloy won't flow




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