Query about forge welding

I have been watching videos of forge welding, what is the 'stuff' the smiths sprinkle on to the metal prior to welding ?
Presumably a flux of some kind?

Plan to have a go at a chainsaw chain blade.
Mark

A flux of some sort. Depending on the smith and how he learned there are a number of possibilities. These include commercial preparations, borax, anhydrous borax, boric acid, straw ashes, sand, wood ashes etc. Some of these seem to work better for some people than others.

ron

Most common is plain borax. Some swear by the anhydrous borax, which has no moisture in it, but that ends when you open it.
There are also some branded fluxes some people swear by but borax works so well I don't think it's worth it.


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Thanks for the info.
I have Borax and plenty of wood ash so I will light up the forge and give it a go.

Mark

Normally for mild steel I use fine clean and dry sand.
For higher carbon or alloy steels I use borax and a as a general purpose version I mix one third borax and fine sand.
I have also melted borax in a crucible until it forms a greenish liquid (keep away from the fumes and provide good ventilation.
Let the liquid solidify ( often called borax glass)and then grind it into a powder, this makes a superior flux that flows very well on the surface and into joints.
I saw a knifemaker doing a demonstation and he dipped the damascus billet straight into a metal bucket with borax into it. The borax bubbled like it normally does and then formed the green I mentioned above. The amount of heat in the billet and the flux couldn't fall off and make mess like it normally does.
So his method achieved the same result that I achieved with melting and grinding but will a lot less effort or messing about.

Interesting info Bruce.
I have tried melting borax as i had heard that it was better, but all it did was bubble up and it ended up light and fluffy, and not really any good as flux! I'm guessing i did not get it hot enough. I'm guessing i would have done it over the forge in a pot or something, it was many years ago and i don't remember.

When borax is heated it loses water and foams/bubbles up. This is normal. After the bubbling it will look glassy from the borax, this is actually anhydrous borax. You can heat the borax separately and apply the anhydrous as flux or you can put the borax on the steel to be welded when it is a few hundred degrees and let it bubble then put it back in the fire where the borax will flux the weld.