Nickel silver flux question

[Matt Wilkinson]

Hello List,  this may be a litttle off-topic, but the internet has a million pieces of conflicting information on the subject..

In my job at UCL the Advanced Propulsion Lab want me to make some thin wall (0.2mm) 304 stainless tubes to 50mm diameter by brazing the lap seam with silver and then cap them with a 0.9mm thick lid/base.  My plan was to use Fillet Pro for the caps, but that option is gone now. My TIG welding is reasonable but I'm not confident I can weld this with my setup. Brazing alloys similar to Fillet Pro are 1kg minimum order quantity.  So I'm considering nickel silver rods, which I happen to have.  Does anyone know the best flux to use?  Would Cycle Design Stainless Light flux be up to it?  I did some test brazes a few years ago but can't remember which flux I used.  

Thanks for any tips you might have.

Matt Wilkinson

London, UK

[FCarcao]

Gasflux Type B works greats with nickel silver and stainless. Type B is the same flux used for brass/bronze rod as well. 

On Dec 12, 2025, at 7:03 AM, Matt Wilkinson <mwilkins...@gmail.com> wrote:



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[Matt Wilkinson]

Thanks!   

Matt

[m-gineering]

son't know about stainless, but cycledesign low fuming bronze flux works
fine with Cu-ni,

Doesn't ceeway do fillet pro in smaller quantities?

On 12/12/25 13:30, Matt Wilkinson wrote:
> Thanks!
>
> Matt
>
> On Fri, 12 Dec 2025, 12:17 FCarcao, <fca...@gmail.com
> <mailto:fca...@gmail.com>> wrote:
>
> Gasflux Type B works greats with nickel silver and stainless. Type B
> is the same flux used for brass/bronze rod as well.
>
>> On Dec 12, 2025, at 7:03 AM, Matt Wilkinson

>> <mwilkins...@gmail.com <mailto:mwilkins...@gmail.com>>

>> wrote:
>>
>> 
>> Hello List,  this may be a litttle off-topic, but the internet has
>> a million pieces of conflicting information on the subject..
>>
>> In my job at UCL the Advanced Propulsion Lab want me to make some
>> thin wall (0.2mm) 304 stainless tubes to 50mm diameter by brazing
>> the lap seam with silver and then cap them with a 0.9mm thick lid/
>> base.  My plan was to use Fillet Pro for the caps, but that option
>> is gone now. My TIG welding is reasonable but I'm not confident I
>> can weld this with my setup. Brazing alloys similar to Fillet Pro
>> are 1kg minimum order quantity.  So I'm considering nickel silver
>> rods, which I happen to have.  Does anyone know the best flux to
>> use?  Would Cycle Design Stainless Light flux be up to it?  I did
>> some test brazes a few years ago but can't remember which flux I
>> used.
>>
>> Thanks for any tips you might have.
>>
>> Matt Wilkinson
>> London, UK
>>
>> --
>>
--

Marten Gerritsen
Kiel Windeweer
Netherlands

[Matt Wilkinson]

Ceeway told me there is no more Fillet Pro.

It seems silver prices are at an all-time high. Brazetec 6009 was £380 per kg in 2012.  Today it is nearly £1200

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[FCarcao]

I haven’t used it, but I have read from other builders that Gasflux 38 is very close to Fillet Pro rod. 

On Dec 12, 2025, at 8:14 AM, Matt Wilkinson <mwilkins...@gmail.com> wrote:



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[Eric Keller]

I never had much luck with Type B with nickel silver, even though some
say it works for them. I would do a test piece first.
I looked up the working temperatures, and it should work. So I'm
apparently doing something wrong.
The working temperature of Nickel Silver is 1720°F - 1800°F (938°C - 982°C)
The working temperature of gasflux type b is 1400 ºF – 2200 ºF 760 ºC – 1205 ºC

The Cycles Design nickel silver flux works much better.
Unfortunately, it doesn't seem like you can buy it.
Eric Keller
Boalsburg, Pennsylvania USA

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[David Bohm]

Nickel silver really works better with a dedicated flux.  Usually formulated with boron Thu making it dark like high temp silver flux.  Gasfluxers also work well. 

Dave B

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[Dan Chambers]

I have a bundle of Metabraze 130, 30% silver rods. 

Good for fillet work and stainless. I use Stainless Light flux with it.

Like Fillet Pro, and a lot lower temp than nickel silver.Happy to ship a few 
Happy to supply some. UK-based. 

All the best, 
Dan Chambers 

[FCarcao]

Gasflux Type B is designed for nickel silver according to their spec sheet.  I have used the black/brown nickel silver flux that Cycle Design sold (still have some) and find it no better than the Gasflux Type B.  I started using the GasFlux Type B last year when I had problems ordering from Cycle Design.  

If you watch Paul Brodie’s fillet brazing videos, you will notice he uses nickel silver with Type B flux before fillet brazing with brass/bronze. 

It is easy to burn the flux when working with stainless because of the higher temps required.  Experimenting is key. 

On Dec 12, 2025, at 5:10 PM, Dan Chambers <dancha...@gmail.com> wrote:

I have a bundle of Metabraze 130, 30% silver rods. 

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[Matt Wilkinson]

Thanks to everyone for the info and advice. Really qppreciate it.

Matt

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[Doug Fattic]

Matt, you might want to talk directly to Gasflux yourself.   (440) 365-1941.  I've stopped by their business and they are friendly in that typical Midwestern way.  Years ago I asked them their advice on what flux to use brazing stainless and they advised their type G - which I've used for all silver brazing after Cycle Design quit.  I get my 56% silver for my students and as I understand it, their 38% is a replacement for Fillet Pro.  They ship internationally.  

Doug Fattic

Niles, Michigan