Any information on firestain (really any at all)

I would like to know about the most annoying thing about working with silver. We all know it. We all hate it. Firestain. Principally I would like to know how to best prevent. Is it with flux or with an alloy and what that flux or alloy would that be. I also have a few questions about it in general which I will list here:

  • does it go away when you reuse scrap? i.e you have some firestained sheet, melt it and roll some new sheet would that sheet have all the firestain from the old sheet plus all the new firestain from being Annealed

  • How can I remove it without destroying detail?

Additionally, I have decided to alloy sterling using yellow/cartridge brass (70Cu30Zn) and from what I can tell it seems only a smidgen softer than standard sterling and very ductile. It also seems to firescale less but isn’t immune to it, does that sound right?

I will eventually switch to a palladium sterling such as continuum but right now I’d like one that is the same (or similar at least) in price to sterling. No more than a dollar a gram :slight_smile:

Anyway thanks for any help


There are many posts on this subject in the archives that offer advice, and here are a few thoughts from myself.

clean the metal so that the flux is able to maintain full coverage

use an anti-firescale barrier flux to protect the metal
(heat metal, apply prips flux, prips flux will dry to a white coating upon contact with the heated metal)
(then apply flow flux only to the area to be soldered)

anti-firescale barrier flux achieves different results than fluxes formulated to wet/clean/flow solder

the barrier flux will take up the surface oxides into the flux solution, until exhausted

(I get best results with Prips flux…sometimes incorrectly spelled Pripps flux in some posts…it has an added ingredient that extends the ability of the flux to absorb copper oxides)

do not heat the metal too hot, and/or too long…

(the flame contains oxygen, so get in and get out, to reduce the amount of time for oxygen exposure to the metal, and to complete the operation before exhausting the barrier flux)

some alloys contain ingredients, such as germanium, which will sacrifice itself to the oxygen, before the copper can interact with the oxygen,or something of that nature…


Hi again,

actually…a good way to approach this question is to research and answer these questions…
I have done, and have a good general understanding, but probably am not the best person to try to spell it all out in its technical glory!

what is firescale? (surface)
what is firestain? (subsurface)
what causes the firescale and firestain?
how do you avoid firescale and fire stain?
how to control heat/ temp from torch onto metal?
what are the best products to prevent firescale and firestain?
what are the best soldering/ annealing/ heating blocks/ materials/ surfaces to help prevent firescale and firestain?
why and how do these products work?
how do you best use these products?


I apologize if this sounds mean (?), but you really must learn to start searching our Archives… This topic has been discussed in great detail many times. You will find a great deal of valuable information there. One of the great advantages of using the archives is that you will hear from many very knowledgeable and very experienced Orchidians who no longer read Orchid. It’s really good general advice to everyone to check the archives before asking questions. Nine times out of ten your questions will be answered there…:-)…

Julie has just provided above a good list of firestain questions to start with, all of which have been answered extensively in the archives. After digesting all that has been written already, you will undoubtedly be in a position to ask some really good new questions…:-)…!

Janet in Jerusalem

Get yourself a big bottle of Cupronil and a we small spray bottle.Warm the metal and keep it hot as you spray a nice white even coat. I have been using it for 20 yrs. and no firestain. Of course there is nothing you can use if you overheat the piece to stop it.

I have searched the archives and found information on fluxes and alloys, I was wondering what people’s opinions are today. Actually I stumbled across a post of yours wondering about s88 and s57na from united precious metals. I too have been considering (quite seriously) s88. How did you find that alloy, no firestain? Worked the same as sterling? Decently hard?

If not, have you used fluxes such as cuprinil, how effective is it?

You need to learn how to use the search function…:-)…

Here are hundreds of archive entries on ‘flux’ from the Orchid search engine:

And here are hundreds of entries on ‘alloys’ from the Orchid search engine:

A google search of ‘flux’ limited to the Ganoksin site came up with 1,960 results:

A google search of ‘alloys’ limited to the Ganoksin site came up with 1,820 results:

You can of course narrow the search to get answers to your particular questions.

Have fun!

Janet in Jerusalem

PS If the links don’t work for you, just do the search.
PPS By the way you’ll find hundreds of entries just on Cupronil (if you spell it correctly…).

From searching the archives, it seems that by using prips flus and not overheating my sterling firestain can be pretty much eliminated? Or must I use an alloy such as argentium, continuum or s88 to prevent such firestain?

I use propane flame. But cover the holes of the burner with a movable ring. This makes the flame oxigen-poor. Very little problem with firestone this way.
Another thing is never quench your piece in pickle. That makes the problem worse. It etches the copper out of the surface of the metal and leaves a layer of fine silver, but creates more firestone underneath.
Always quench in water first.

Quenching in pickle creates neither fire stain nor fire scale. I always quench in pickle and have neither.

Janet in Jerusalem

Perhaps it should be stated not to put silver into a pickle with steel of iron tongs. There is some alchemy that goes on between the silver and the iron and the pickle that creates scale of one type or another. A nightmare to clean off, maybe not a nightmare but certainly more work than you need to do.

Use copper or wooden tongs.

Don Meixner

Hello, I’m not an expert in jewelry making but here is some information I have experimented with that seems to work on fire scale on sterling silver.

This is some of the stuff I think we are talking about.

I make a salt water solution 4 parts water and one part salt. I put a copper conductor on one side of my beaker and a copper conductor on the other side. The negative side(left side) is on your part side(Ring) with a hook on it to hang your part or ring.Not sure if the part side needs to be copper but it works. The positive side is on the right side with just a copper piece of metal.

If you reverse your connectors you put more firescale on your part.

You can use a 1.5 volt battery but it takes longer. I used an adjustable rectifier an apllied 3 volts. It takes about 1 1/2 minutes.

1.5 volts applied will take longer.

I did not use any preventitive measure like boric acid or and alcohol or cuprinoll prior to soldering. I did not pickel it after my soldering . I did try to polish it with a yellow Rio cloth which just shined up the fire scale.

So I let it fizzle in my salt water bath at 3 volts for 1.5 minutes.

When I pull it up it looks like this.

When I wipe it off with with just a paper towel, it looks like this.

When I buff it up with Rio’s yellow cloth it looks like this. Didn’t have to use any sand paper.

I put it to a buffing wheel.

I put it back into my salt water bath with the terminals reversed after I had polished up and it puts the fire scale back on it.

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Thanks, I was wondering how quenching in pickle would cause firescale or stain. I always quench in pickle, which still might be a bad idea for health concerns. Got it in my eye once, that was not a fun afternoon…


I believe it is safer(?) to quench in water, then put item in pickle. so that you don’t get splattered with pickle.