- 1 Related Videos
- 2 What Does Firescale Look Like?
- 3 Oxidation, Firescale and Oxygen Concentrators
- 4 Question: My ring has firescale, how can I remove it?
- 5 Question: I have firescale/stain on my piece – how to remove it?
- 6 Should I protect my piece from firescale/firestain with an anti-firescale coating when soldering?
- 7 Does Pripps Flux work better than boric acid and denatured alcohol for preventing firescale/firestain?
- Finishing Jewelry
- On Pickle, Acids, Crock Pots and Baking Soda
- Soldering 101 – Oxidation, Flux and Firescale Prevention
- Torch/Gas Questions
- Vermeil, Gold Plate and Gold Filled
What Does Firescale Look Like?
How does fire scale present on a polished piece of silver jewelry?
Please see updated information on firescale and fire stain on my webpage: Soldering 101 – Oxidation, Flux and Firescale Prevention. Updated: 1/27/17.
(firescale/stain on silver) I think this link to my page: Soldering 101, will help. Firescale/fire-stain usually shows up (clearly) when polished. It looks like a purple bruise.
Oxidation, Firescale and Oxygen Concentrators
“I’m producing a lot of fire scale. My studio is in my house, so I’m reluctant to set up acetylene. Is there a larger oxy/propane torch you might suggest? I’m thinking of getting an oxygen machine to eliminate buying those expensive oxygen bottles from the hardware store.”
Is it firescale or is it oxidation, that you are experiencing? Here’s my page on the topic. If it is oxidation, moving to the mapp gas and getting a larger torch tip could help. Maybe, it is taking too long to heat your metal. When you fire metal too long it allows for considerable oxidation to develop – especially with sterling and base metals like brass, bronze and copper. A larger torch tip, like this #7 , the Melting Tip or the Twin Tip (you can solder from both sides at the same time), should help heat things up faster. Have you checked out Argentium silver? Very awesome metal. It contains Germanium, which is released when the metal is heated. The Germanium coats the outside of the metal, reducing, drastically, the firescale and oxidation. It also takes a long time for it to tarnish – although, rates vary depending on what chemicals are present in the environment. Please see my webpage on sheet metal and wire.
If you are getting a lot of firescale, look into reducing your heat, completely coating your metal with flux or an anti-scale product, or don’t finish to a high shine (see soldering 101 page for explanation). You can also switch to Argentium. More information on firescale can be found at my Soldering 101 – Oxidation, Flux and Firescale Prevention page. You can try a product like this: FirescoffTM.
Here’s a brief discourse on Scott’s experience with an oxygen concentrator, at Ganoksin.
Question: My ring has firescale, how can I remove it?
“I’m trying to solder a gold filled ring, and I have bought the Firescoff. I have already followed the instructions step by step, but still can’t solder a perfect gold filled ring, it still has the firescale. Could you please tell me how to do with this?”
Firescale and Surface Oxidation both occur in metals containing copper like your gold filled metal as well as sterling silver, brass and bronze – among others.
The same is true of most firescale. When the firescale does show up is usually during the final polishing stage and appears like a gray/purple bruise on the metal. (See my webpage: Soldering 101 – Oxidation, Flux and Firescale Prevention for an explanation!)
Question and Answer: How to remove firescale/stain.
You state you: leave too many “fire marks” – what do you mean by that? Are you using pickle to clean the metal after soldering? Or are you seeing that gray bruising after polishing (firescale)? If you are seeing firescale, try doing something like what is in this Rio Grande article. If you have oxidation from soldering, try a nickel pickle: Here’s one article from Hoover and Strong. Here’s a product – Rio Clean Pickle – designed for nickel, brass and bronze.
Question: I have firescale/stain on my piece – how to remove it?
I’m a total newbie and also don’t have any equipment yet. I am taking a jewelry class. I just made 2 pieces and didn’t manage to polish the fire scale off before running out of time. What would you recommend to try to polish the fire scale away? It’s mostly around/under bronze stars that are soldered on to the sterling piece. It’s tricky to get at but very noticeable. Desperate to remove it!
I’d really like to try to achieve a mirror finish. Seems like sandpaper/finishing paper might be the way to go. My other thought is to take it to a local jeweler and see if they can do anything with it. I’m attaching pictures of the pieces so you can see what I’m talking about. Recommendations of specific papers to buy would be really helpful.
Please see my webpage: Soldering 101 – Oxidation, Flux and Firescale Prevention for updated information on the formation of firescale/fire stain and how to avoid and remove it.
Firescale/firestain is difficult to remove and the only predictable way to remove it, that I’ve found, is with sanding or etching. You could try using 50% sodium bisulfate based pickle and 50% hydrogen peroxide. One of my viewers swears that that works. I need to experiment with it. Check the metal every couple of minutes to see what’s happening. You should see bubbling around any areas that contain copper. Usually, the metal will have a matt finish, after the immersion in pickle and peroxide so, you might have to burnish with a brass brush or use a buff with rouge. It may work – it may not.
Should I protect my piece from firescale/firestain with an anti-firescale coating when soldering?
“Since you are the great and powerful guru of silversmithing, maybe you can help me.
Flux is used at the points you intend to solder to aid in its adhesion. When soldering, do I need to protect the piece from fire scale with a boric/alcohol bath first?
I just purchased Battern’s liquid flux and thought I was all set. Now I am receiving advice about the bath first. What are your thoughts? What brand flux do you use?”
Total immersion or coverage would only be important if you were concerned with fire scale/fire stain because you were creating a mirror finish, at the end. According to the research, that I just completed, if you are working with sterling silver, bronze, brass or gold (besides 24K) you should either: 1. flux the entire piece or 2. use a fire scale preventative. Check to be sure that the preventative can also be used as a flux. See my updated information on oxidation, fire scale and fire stain.
If oxidation is present in the metal, and it has been through several soldering/annealing steps, and you want a mirror finish, the heat from the buffing process will probably bring the copper molecules up to the surface in a random pattern. It is explained more in the link above so, please check that out.
Does Pripps Flux work better than boric acid and denatured alcohol for preventing firescale/firestain?
Do you create a high polish on your finished pieces? That is when the firescale/stain shows up. It doesn’t always happen though.
I don’t think anyone type of preventative works any better than another – although, people can get pretty heated up in the defense of their firescale/stain preventative. I use just plain flux and try to avoid overheating. Anything that reduces the amount of oxide development, works. The temperature range of the flux/dip is crucial – if pieces are heated past the max temp range, the flux/dip stops working. Most have working ranges of up to 1800°F. I think, that if you aren’t seeing firescale/stain, then you are doing something right and I’d keep doing whatever you are doing. Although, you do have most of the ingredients so, you could make some up and see what you think. Wish I could be less vague but, I haven’t found anything that I feel is superior to another – yet!
The best way to avoid firescale/stain, altogether, is to use Argentium silver.
*There are other fluxes/dips that have higher ranges but, they are usually used for platinum. Also, soldering on charcoal helps because it creates a reducing atmosphere.