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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.

Thread: London Model Engineering Exhibition - Alexandra Palace
08/01/2019 15:20:14

The most knowledgeable source of information regarding silver soldering and brazing for the model engineer is there.

Just ask Glen or Shaun on the CuP Alloys stand.

Regards to all


Thread: Soldering
11/12/2018 12:10:10

Hello Iain.

Not to be sidetracked I return to your original request about soldering.

First off - neither of the two fluxes in the picture are suitable for use with what appears to be silverflo 40. There is what appears to be a JM label but unless there has been a dramatic turn around I do not believe that the material was supplied to you by JM. They do not supply it by the rod! And CuP do not use JM labels!

So what advice does your supplier offer? I would be interested to know.

Secondly. You should be able to melt the silver solder with a plumbers torch - as long as you are generating enough heat.

If the steel is a dull red the silver solder should melt a 40% silver cadmium free alloy

Thirdly, if you can melt the silver solder but it doesn't flow then change your flux to one with a longer life eg HT5 from CuP Alloys.

Fourthly, if you can't melt the silver solder then use a lower melting point alloy eg 455 from CuP Alloys.

Why do I keep plugging CuP Alloys - because they are the company that can supply good quality materials and give the technical help to get the right results.

Silver solder is expensive ..... especially when it doesn't work!


Thread: How does solder stick ?
09/12/2018 12:59:09
What a marvelous response from Robin.Brilliant!A terrific picture that shows what happens and illustrates just why thin solder and brazed joints are stronger. Thanks for your contribution to the campaign.
Thread: Lead Bearing Solder is Banned
08/11/2018 13:46:24

Article 67 of REACH shows that legislation has been passed banning the sale of any lead bearing materials to the general public. This includes soft solder.. The maximum allowable content of lead is 0.3%. Above this figure, all such materials are regarded as TOXIC

As far as I am aware, very little effort has been made to advertise this legislation. The onus is on individual companies to keep abreast with such legislation via government websites.

I have it on very good authority that the H&S Executive working in tandem with the Trading Standards Authority have tried to enforce this legisation.

I repeat, the legislation, only applies to the general public. It does not apply to any professional organization or company. I believe the argument is that any tradesman is not at risk but the man in the street is. The former knows what he is doing- the latter doesn't.

During a visit from the authorities, it was pointed out that far greater quantities of lead bearing solders are readily available on the High Street to the general public, from several warehouses, merchants and manufacturers. The investigating team was directed to these outlets.

They were not aware of this situation! They left to visit one source immediately.

Because, they do not want to be seen as discriminating against small companies, they have held off any legal action until until they can bring all outlets into line - a logistical nightmare!

So, it is coming.

CuP Alloys are already investigating other alloys that offer similar soldering characteristics in order to meet any demand from the model engineer.

It is not illegal to use lead bearing solder. The law prevents it from being sold or placed on the market - that means sampled or given away. It is very similar to the legislation forbidding the sale of cadmium bearing silver solders. After all, it emanates from the same European capital.

Where will it end? Free cutting phosphor bronze and mild steel are in their sights!

There will be no further comment from me!


Thread: Brazing Mild Steel
02/11/2018 10:08:53
A couple of points to add...
I said during my talk at the Fosse that cleaning of the joint is not your job - it's the function of the flux. The joint must be clean at brazing temperature not at room temperature. You cannot achieve this but the flux can and will. Using citric acid is a waste of time. Use it if you wish but just make sure that you wash it off. The heat from the torch will leave a deposit of citric acid salt that the flux will not remove. Result - poor joint!
The amount of detergent used in making the paste has no deleterious effects.

I also stressed at my talk "ask questions,- don't be afraid to ask". Why didn't you?

There is more information and technical help on silver soldering and/or brazing at CuP Alloys than eBay, Amazon,car boot sales, welding
distributers etc put together.

Why not use it?

At worst, you will be talking to someone who has been in this business for 24 years. Strike lucky and he has 49 years!

I'm getting old!

31/10/2018 09:22:28
Hi Bill,
Borax does not become effective until it reaches a temperature above the melting range of most silver solder.
So you have to overheat the alloy. Ok, you could, repeat could, make it work, but why go through the hassle?
A couple of quid buys you the right flux that enables you to do it properly.
28/10/2018 11:29:33


It is identical to soldering. It is only an undocumented international convention that distinguishes between the two. Quite simply, if you are making your joints at a temperature below 450 deg C then you are soldering.

Above 450 deg C then you are brazing.


IT HAS NOTHING TO DO WITH THE HEATING TECHNIQUE. Gas torch, furnace (vacuum or atmospheric), electrical resistance, induction are all viable heating techniques to produce brazed joints

Jet engines are brazed with gold/palladium brazing alloys.

Automotive components are brazed with copper and copper brazing alloys (this includes brass!)

Nuclear reactor components are brazed with nickel brazing alloys.

Steam boilers, bogies, clocks, are brazed with silver brazing alloys.

Look up the term "brazing" in any source and you will find that in the definition there are two words that repeat and those two words are "CAPILLARY ATTRACTION"


All too often silver brazing alloys and brass alloys are not used to braze two components together. They are used to stick two components together and block a hole and that is expensive. Look at some bicycle frames, office furniture and the multitude of joints made in steel using brass rod and oxy-acetylene torches.

I have supplied, in the past and for over 18 months, a company in excess of 200 kg per month of a silver brazing alloy that was used to do precisely that. The financial risk became too great and the orders were passed directly to my supplier.

The customer refused to change the joint design and to use the alloy as a brazing alloy.

In doing so they failed to take advantage of the many technical advantages of using the process. Silver solder, because of the price, is only used because it satisfies a technical requirement.

It will join a wider range of parent materials than welding.

It is carried out at lower temperatures - less distortion.

As a filler metal, it is more corrosion resistant.

It produces leak free joints.

It produces joints stronger than the parent materials.

It offers better strength at elevated temperatures.

It offers a good colour match to parent materials.

It can be carried out using relatively inexpensive equipment. Propane/air torches are fine.

If none of the above are important then save your money and use soft solder, or glue or screws!

In all cases, the use of a silver solder, despite its price, produces the cheapest cost per joint. If as an individual you can't reach this conclusion, you are are not using the product correctly. Examine your joint design (gap and length), examine your heating technique to get the alloy to flow precisely where you want it, examine the form in which the silver brazing alloy is being used. There is more than 1.5mm dia rod.

As regards, other companies ceasing to sell silver solder, I believe that was due in no small way to CuP Alloys. They passed on the benefits of their large buying power with German and Spanish suppliers to the model engineer and backed that up with good sound technical back up.

For more information, there is a book available from CuP Alloys.

"A Guide to Brazing and Soldering - everything you wanted to know about Silver Soldering but were afraid to ask"

I cannot speak too highly of it!



PS Brass strip and borax will produce excellent joints. But please "braze" with it and not simply stick the pieces of steel togerther

Edited By CuP Alloys 1 on 28/10/2018 11:30:45

Thread: A New Golden Age of Model Engineering Exhibitions
23/10/2018 11:14:59

But as Shaun has said prices are made as competitive as possible but that will not satisfy some.

True Story from the Midlands Exhibition.

"I'm not paying that. I'll wait and get it off the internet"

The product is not available, nor will be legally, on the internet. What he meant was,

"I'll wait til somebody robs you and I'll pay the thief"

There you go.


Thread: Brazing carbide tips
21/10/2018 11:26:45
Hi Michael.
See personal message.

Edited By CuP Alloys 1 on 21/10/2018 11:44:27

Thread: JB cutting tools .com
19/10/2018 09:56:44
Have spoken to Jenny and Paul. This situation is simply a breakdown in communication. They don't recognize you but have urged that you ring Jenny directly on 01246 418110 on Monday. They are at the Midlands exhibition til Sunday.
Thread: Oxy Acetylene or Oxy Propane?
02/10/2018 14:36:30

Hi Ron,

One of the better answers will be found by googling

mapp gas



Thread: Silver Soldering - A Simple Process Made Difficult
30/09/2018 08:49:02
You tube-unlikely.
Website - definitely.
27/09/2018 15:10:02

Silver Soldering - A Simple Process made difficult is the title of the latest talk from the CuP Alloys Roadshow aimed at increasing the knowledge of the subject with the model engineer.

It discusses how to make a simple process difficult by not adhering to the basic principles. Follow them and you will be successful. There will be plenty of opportunity to ask any questions. Don't be afraid to do so.

There will also be news of a recent directive from Brussels that will affect the model engineer.

The talk can be heard Thursday, Friday and Saturday at the forthcoming Midlands Model Engineering Exhibition at The Fosse.

Edited By CuP Alloys 1 on 27/09/2018 15:11:28

Thread: Silver soldering
09/09/2018 13:13:05

The biggest problem to be overcome when brazing carbide is the effect of the very different coefficients of expansion of the two materials that could cause cracking.

Help yourself by using the lowest brazing temperature ie something like 455.

Create a thicker joint than you would normally. Say aim for 0.2mm.

Don't quench the joint. Let it cool as slowly as you can. Immerse it in dry sand or wrap it in some insulation material like a clay wool blanket.



Thread: Solder..?
24/08/2018 08:29:05
Hi john. After melting, silver solder ALWAYS flows to where it is hottest. Examine your heating technique to create the best heat pattern.
PS The book will guide you!😏
Thread: Pickle
25/07/2018 09:07:15

WOW ..............

All getting a bit personal now.

It will be handbags at dawn next.

Get me a ticket! Can't wait!


23/07/2018 09:19:42

10 gms of citric acid salt per litre of water.

Check it out at the local wine shop or supermarket or eBay or welding distributor!

Yes I'm sure.

22/07/2018 07:35:21
Hi John.
Answering the original question..

10 gms per litre of water and
Get it from


Thread: Want to put a brass union in a Stainless Steel? tube
05/07/2018 16:02:36
Make sure you use a non magnetic steel to a avoid crevice corrosion.
Then use 455 silver solder and HT 5 flux.
Thread: Silver soldering problem
02/07/2018 14:37:37
Hi Bob.
Email details to me with the grade of silver solder you are using.
If the solder melts but don't wet the brass you have a flux problem. The flux is not compatible with the solder/heating technique/parent materials.
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