I have made forge welds in my forge in the past without a lot of problems. Even doing it in the propane forge I could at least get a tack even if it wasn't a solid weld. Tonight I tried and couldn't get even an attempt at tacking, much less a weld. Everything seemed the same as when I have done it before, but no-go. The only thing that comes to mind is the fact that last weekend I did some cutting and grinding without watching where things were going and I got a nice coat of aluminum dust in my coal barrel.

Am I being superstitious thinking that the two may be connected?

Not likely - it's been more or less proven, albeit through mostly anecdotal evidence, that small amounts of contamination don't prevent forge welds from sticking. It's more likely that you had a dirty fire from clinker and either didn't get it hot enough - or pushed too much air through the fuel pile and burned the material. These two reasons seem to be the most common reasons for failed welds, with poor fitup possibly a distant third.

Caution: Aluminum dust plus iron oxide equals http://www.iforgeiron.com/forum/f21/thermite-4935/ a very dangerous substance. Aluminum is probably not a good thing to have in your forge fire, I would not be surprised if it was doing strange and wondrous things in your forge.

I know it's been a long time since I started this, but it's been a cold winter and I haven't been in the shop near as much as I'd like. We have a warm day a while back and I tried another weld like the one I was having problems with. The two things I did different were being far more liberal with the Borax and I used about 1/4 the air I had been and let it heat a lot slower. The weld came out much better. The only problem I had was a small (1/8") crack at the back edge that didn't take, the rest was rock solid. I imagine that's just a lack of experience at work there.

Thanks!

When in doubt, go back to the basics. As HWooldridge said, a clean fire, lots of soaking heat so the center of the metal is the same temperature as the surface temperature, controlled air blow, sprinkle with your choice of flux (or no flux), and just bump the two metals together with the hammer to start the forge weld.

Flux is not glue, so more is not always better. Just a coating of the metal, a sprinkle, will usually work.

When you see the wonderful photos of sparks being sprayed all across the room from the forge welding process, it is all Hollywood. Those sparks are your forge weld being thrown to the 4 corners of the shop.

Practice, practice, and more practice makes good forge welds. On the days when the metal laughs at you, ask Mr. Lincoln or Mr. Hobart for their blessing. (grin).

Bentiron's link to the Mokume Gane Video (from Germany) was most interesting at the last when the smith started "hammering" - they used many light taps spread out along the length of the pieces being welded. No smashing or banging, just taps. I am guessing that is what Glenn is speaking of. All parts heated through and through and they stick together, once hit.

Jeremy, when it warms up a tad and I get a little break from studying, we'll get together and see if we can get you making more solid welds. I'll call you, before long. :D

Slow and easy long soaking heat. Remember pull it out brush it off flux back in slow air and when it looks just the same color as the coals around it your almost there. I have even welded a box of paperclips together this way .
Firegnome