Bentonite: am I doing it right?

[Luke Rieman]

I read on here that some people use bentonite cat litter in a tray as a sacrificial refractory when forge welding, so as not to destroy the floor of the forge with flux. I tried some (Perlax brand, I think?) It was the cheapest and claims to be 100% Fuller's earth aka bentonite, hopefully.

I found, however, that the top layer fused together at normal forge temps, and at forge welding heat the whole thing melted into goopy lava. Did I do something wrong or is this the expected outcome? I still managed to get some okayish welds but it wasn't much fun trying to extract the workpiece from the goop every year. 

I had tried previously using coke in the same tray and this worked well. The coke I have is low quality though and I don't have proper fume extraction so that isn't a long-term solution for me.

[pnut]

I just use a split hard firebrick on the floor of my gas forge for forge welding. Clay vitrifies in my solid fuel forge and gets glassy when I forge weld so I'd expect the same thing in a gasser. 

Pnut. 

[ThomasPowers]

Note that "Fullers Earth" is a term that is applied to multiple types of clay so it does not mean it's Bentonite; it means it *may* be Bentonite.

[BillyBones]

My daughter came home one time with some stuff that was supposed to help her complexion. It was a little bad of fullers earth she got from the beauty shop. She paid over $10 for about a 1/4 C. of it. So i told her i could have given her as much as she needed for free. That was when i explained she was putting cat litter on her face. 

 

[Glenn]

Do hope you mentioned that it was NEW cat litter she was using. (grin)

[Luke Rieman]

On 1/22/2021 at 3:21 PM, ThomasPowers said:

Note that "Fullers Earth" is a term that is applied to multiple types of clay so it does not mean it's Bentonite; it means it *may* be Bentonite.

Thanks, I think this may be my issue as the forge was barely even hot before the stuff had turned sticky. I'll try getting some which actually states bentonite on the label, but otherwise I guess I'll stick to hard firebricks. They're just so expensive here for what they are 

[ThomasPowers]

Are you buying them from a mason's supply?  I don't know where "here" is so I can't make suggestions on where to look for hard fire bricks cheap.

[Frosty]

Welcome aboard Luke, glad to have you. If you'll put your general location in the header you might get a chance to hook up with members living within visiting distance. A lot of information is location specific hence Thomas's hint about where here is. I can buy 3,000f split hard brick for about $2 ea. at the local concrete batch plant / masonry supply. 

A high alumina refractory liner will pretty much solve the borax welding flux erosion issue. OR a good kiln wash, Plistex 900 doesn't much care about HOT welding flux.

Frosty The Lucky.

[BartW]

I just use plate stainless steel, hammer it in a low bowl shape, and use that to catch borax. It's cheap; easily replaceable ...