Good morning! 
after forge welding, I occasionally get borax pushing through my finish. Why does this happen and how do I address it?

I've had it show up at or close to the weld site, say where your poker is forged into contact before the weld but not that far away. If you haven't waxed, oiled, etc. it soaking in water will dissolve the borax but it it's trapped between the point and hook you might have to wedge them apart slightly to allow the water access. Heating up a little will make it dissolve better too. A little above boiling won't effect the steel but when you put it in water capillary action will draw water into any space large enough for water molecules. Re warming it will drive the water back out. A couple few repeats might be necessary. 

Lastly, how much borax did you use?

Frosty The Lucky.

I use vinegar to neutralize borax residue before applying a finish. I just brush it on and let it sit "a while" then rinse with water.

I can’t control the wind. All I can do is adjust my sails. ~Semper Paratus~

Good Morning,

Try using Garden Lime instead of Borax. It works a treat.

Neil

Are you using just regular old Borax? Or are you cooking it? I have found that since i have started using anhydrous borax it is no where near as messy and do not have to use but a small pinch. I took a sauce pan from the kitchen, do not tell the wife, put about a cup of borax in it on my fire until it all melts, pour it onto a tray to cool. Then pound it into a powder. Oh, and do not try and make sauce in the pan later, hide it from the wife in the shop somewhere. 

Since i have started using it i have only had 1 failed weld in the past 6 months also. 

Next time, go to a welding supply (not a big box hardware) and buy a can of powdered welding / brazing flux, they are anhydrous borax, boric acid and some color for brand recognition. Last can I bought was $26 but that's a couple decades ago, "Petersons" WITHOUT the powdered iron. Keep the can or container closed or it won't be anhydrous very long. 

It doesn't take much flux, even 20 muleteam. Flux isn't glue it's just there to prevent oxidization of the joint surfaces and if you don't clean them, carry scale and dirt out of the joint. 

Brush, sand, file, etc. and flux LIGHTLY the joint faces BEFORE you wire, tack weld, etc. the joint together. Fluxing the outside doesn't hurt but don't wait till it's at orange heat. Orange heat is where iron / steel, oxidize rapidly, on contact with air in fact so waiting till it's oxidized before fluxing is contraindicated. Warm it till a little bit of flux on the surface melts, THEN flux the outside of the billet. Oxidization will be minimized and protection maximized.

Your flux doesn't need to squirt dirt and scale out of the joint if there isn't any. No?

Frosty The Lucky.

If You heat plain Borax (decahydrate) at 75 °C it decomposes to it's anhydrous form. 

https://en.wikipedia.org/wiki/Borax

 

No, it doesn’t. Heating regular borax drives off the excess water on the outside of the crystals, but doesn’t do anything to the water trapped inside the crystals. For more detail, see:

 

Getting back to the original question, artist-blacksmith and teacherElizabeth Brim cleans up her forged welded pieces by giving them a soak in muriatic acid.

On 11/5/2025 at 11:20 PM, The Forest Ninja said:

If You heat plain Borax (decahydrate) at 75 °C it decomposes to it's anhydrous form. 

You didn't bother to watch the video or read the WIKI article did you? 

The ONLY times I recall seeing a post from you has been a similar display of a total lack of knowledge about the blacksmith's craft. Seriously, you couldn't make a tea kettle of water anhydrous at 75C, sure it'd burn you if you poured it on yourself but that's not hot enough to make tea or coffee.

If you'd like to learn something act like it.

Frosty The Lucky.

I got the impression that Forest Ninja was being facetious.

The 3 of You above don't know about Chemisty.

 

The thing I know about chemistry (which applies to many disciplines, both scientific and otherwise) is that citations are more important than personal attacks. The article I linked above not only describes the difference between dry borax (which has no water on the outside of its crystals, but still has water trapped within them) and anhydrous borax (from which that trapped water has been removed), but quotes from reliable sources and gives citations. For example:

Quote

Anhydrous borax is produced from borax through high temperature fusion. On cooling, the clear, glass-like material is ground into fine white granules.

And:

Quote

Most of the water of hydration is removed from the decahydrate (see below) by evacuation at 25ºC for three days, followed by heating to 100ºC and evacuation with a high-speed diffusion pump. The dried sample is then heated gradually to fusion (above 966ºC), allowed to cool gradually to 200ºC, then transferred to a desiccator containing P2O5 [Grenier & Westrum J Am Chem Soc 78 6226 1956]. [Becher in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I pp 794-795 1963.]

The link to the source of these two quotes is https://www.chemicalbook.com/ChemicalProductProperty_EN_CB6233954.htm.

If you have any information or data that contradicts these quotes, feel free to provide it. 

I don't suppose you have anybody to moderate this kids posts do you John? So far he hasn't posted anything but childish nonsense and personal shots. I mean seriously, this isn't a 6th grade cafeteria. Are you thinking he'll maybe read something other than from his friends?

I would've 86ed him after he ignored the second warning.

Frosty The Lucky.