A fairly basic pattern-welding question

Hello all,
I decided to try my hand at making some damascus-style pattern welded knife blanks, and it's working more or less all right. Just a couple
of quick questions for those of you who have done this, if you have the time to answer.
First off, what I'm doing, at least for this first try, is using an old chainsaw blade that was bead-blasted and then soaked in acetone to get it as clean as possible. I then had a friend of mine fuse it together and weld it to a handle to make it a little easier to work for. So far, so good. I've got 20 mule team borax for flux, and while I've heard that anhydrous borax is better, this stuff seems fine, and is doing the job well enough. I'm doing all the heating in a forced air propane forge, and have missed a couple of welds, but about 90% of them seem to be pretty good.
All that being said, here are the questions I have been asking myself while working on this. The first is a matter of flux- being a little less than completely confident about my forge welding technique, I've been putting about a tablespoon of borax on each time I put the piece back in the forge. As you might imagine, this has made a real mess of the firebricks I've got on the bottom of the chamber. Any clue as to how much flux I *should* be using? It's working, but I get the feeling I'm probably overdoing it a bit.
The second is a matter of gas setting- I can't for the life of me remember if I want more or less oxygen for the best weld. So far, I've been running the mix really gas rich, with a low stream of forced air. Again, it seems to be working all right, it's just a matter of figuring out if I'm making more work than necessary for myself.
Third is dealing with small cracks. At this point, after about 3 folds and maybe 12 or 13 heats, it's looking pretty good- but there are one or two areas where there is a small crack on the surface that is apparently a spot where the weld did not take fully, as they look like the partial outline of a chain link. Any chance that just continuing to flux the blank while drawing it out will close these up, or do I need to grind those out before proceeding? (they're visible, but not very deep)
And last, but not least, is bringing out the pattern- it'll be a few days before I really need to start thinking about that, but it never hurts to plan ahead. I have a quart of ferric chloride that I've been playing with by etching copper and brass with it, and I more or less intend to etch the finished blade with that- unless there is a good reason not to. Any opinions on whether this will work better than muriatic acid from the hardware store? I'm also wondering if the etch needs to be done before or after heat-treating the blade- a lot of the pattern-welded blades have a striking black and silver contrast, and I have no idea if this is a matter of heating it after etching, and then polishing the high points, or if the etch itself makes this happen.
Any hints, tips or tricks would be greatly appreciated. I'm sure this one is going to turn out to be ok in the end, but it never hurts to get advice whenever possible.
Thanks!
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Just a quick note, you might want to pick up Jim Hrisoulas's book 'The Pattern-welded Blade' and the video he did. It will answer a lot of your questions.
(snip)

While you don't have to use Anhydrous, I'm not that happy with 20 Mule Team. They seem to have added something to it that makes it stick a lot more, which is a pain when you have to wire brush the slag off the anvil and the hammer. I got a pail of plain borax from a chemical supply house and it behaves like the 20 Mule team I remember from 8-10 years ago. A jeweler friend of mine pointed out some changes in behavior of 20 Mule Team she noticed when using it as a soldering flux, which lead me to try changing my flux. As to the amount, you are overdoing it. You really only need enough to coat the piece and it should last through 2 or 3 heats, after which you should wire brush it off and reapply a little more.
Also, get a chunk of high alumina kiln shelving to use as a floor to your forge. It will take a little longer to heat up, but hold the heat well and give your forge a little more thermal stability. It stands up well to flux, and when it is finally eaten through enough to be replaced, you can just take it out and put a new one in. As to what you have in there now, kitty-litter (plain clay type) is good at sucking up the flux you already have in there. Then it can be raked out.

You want it rich, but you don't have to have it really rich. Just enough so it cuts down on scaling. If you have enough propane (in a non-blown forge) that makes it out of the forge door before it burns, you have it rich enough. I'm not sure what to look for on a blown forge, but if you put a plain piece of metal in, and it doesn't seem to really scale up until you take it out, you are probably rich enough.

There are several reasons these can form. Yes, fluxing and hammering can weld them up if they have good mating surfaces (the hammering can really help on getting them to mate up). If they are deep, chiseling them open, wire brushing them out to get out any slag or crud, and re-fluxing can work. If they are shallow and you are pretty confident of that, grinding can take care of it. But I've run across ones I though were shallow, but ran deep enough to ruin the piece when grinding.

I'm not 100% sure, but I think if you've used your ferric chloride to etch copper it may copper plate your blade. (quick search) http://home.comcast.net/~jeshern/copper.htm
However ferric chloride is a good etch, as it leaves a good contrast and does give you a little topography. You shoud do it after heat treating, and clean up after the etch with cold water and 600 grit paper to bring out the pattern. Don't sand too much, just enough to get good contrast.

Hope that helps!         Todd
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wrote:

Yes, it is kind of a sticky mess. I thought that was just the price I had to pay to use a flux in a forge- well, if this one turns out, and I decide I want to keep at it, I'll invest in a better grade of flux. It definately helps to know that refluxing after every heat is unneccessary.

I'll give that a try.

I don't know if it's because of the flux or the mix, but it's not scaling at all with what I've got it set at now, and it's plenty hot until the tank begins to freeze up (I've really got to get my 100 pound tank down to the co-op and get it filled, the 20 pounder is a PITA!)

Well, right now I need to do some pretty heavy drawing out, as it's about twice as thick as I'd like it to be, so I'll just keep some flux on it and hope for the best. In a worst case senario, it was an old junk blade beyond any hope of repair, and it's good practice. If it's cracked, but has a good pattern, I can always use it for inlay.

Perfect- I'll just make sure to get some more ferric chloride, as it's pretty cheap anyway.

Sure does, thanks for taking the time to reply.

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(snip)

Well, if you want to ping my e-mail with a mailing address, I'll mail you about a cup of the straight sodium borate pentahydrate that I have (though it might be decahydrate by the time it gets to you).
(snip)

Sounds like you are doing fine then. (Yeah 100# tanks are a lot nicer to use.)
(snip)

Mixing it at about 3 parts water to 1 part ferric chloride seems to give a lot of people a fast and fairly clean etch.
    Good luck.         (now I just need to get my power hammer finished...)
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(snip)

Not awake yet this morning. Sodium Tetraborate Pentahydrate.
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Todd Rich wrote:

Get the three books he's authored, number 4 is coming soon.
Every time I email Jim or reply to him on the Yahoo! lists I always hint at a DVD version of his videos. Tapes don't make it to Australia undamaged.

Personally I didn't find that effective, mine just got chewed up real quick, I use the hard BBQ fire bricks these last a bit longer for me. Maybe the standard house hold borax has too much water in it (maybe borax isn't borax... woof woof says the old dog).

Absolutely you'd want virgin acid.
Regards Charles
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If you ever get a chance to stop by his shop, it is an experience. And yes, all the books by him a very good to have.

Hmm...that is weird. I've had the original in mine for about 8 years now. (However I really haven't used it for 6 years of that due to no place to really work) and it still hasn't eaten more than a 1/3rd of the way through. I've seen several types of kiln shelving, and this is the type that looks like amost like granite and feels very dense. The water in borax shouldn't have any effect, it gets burned off very quickly.
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Prometheus wrote:

The feric chloride will plate the iron/steel with ALL of the copper in solution, BEFORE it begins etching the iron/steel...but it can't etch it through the layer of copper.
Reserve your current FC for etching copper, etc, and get a NEW solution for the blade.
John
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On Sat, 29 Dec 2007 18:22:05 GMT, "John O. Kopf"

Will do- thanks for the advice.
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That's handy to know for other purposes though :-) Regards Charles
John O. Kopf wrote:

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Prometheus wrote:

Put a bunch of the Borax into a tin, heat it untill it melts. It'll foam a bit (or a lot). That's the water coming off. Allow to cool, then crush the remains, to powder. Anhydrous Borax! TaDaaa!

Have flux in a wide dish, like a garbage can lid or similar. Hold the work over the container, sprinkle on flux, catching remains on container. Minimizes the flux in the firepot or box.

Adjust for enough heat,and minimal scale.

Can you work around them in the final design? A modern looking knife with clean lines looks poorly done if there are splits or gaps showing, but some like the look on blades for reenactors or period looking pieces.
Most of the chain and cable that I have seen was only welded one time, and forged to rough shape. This maximizes the pattern. Too many folds, and the steel all blends together into a grey mass with no definition. Should not be as muchof an issue if there is some nickel in the pins, but at the cost of it these days, what'r the odds.

Not sure if you have ruined the Ferric by exposure to copper or not. You will see when you go to use it. It may deposit copper onto the steel. Try etching some plain steel in it. It would not do, to try it on your stock, as you would then contaminate the next batch of ferric when you went to etch your blade. I used straight Ferric and had results I was pleased with. Some use it cut 50% with water, and say it cuts a cleaner line at the juncture of the two metals.

Cheers Trevor Jones
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wrote:

I'll give that a try- would you normally heat that in the forge, or by some other method?

I've been doing it over the box, only problem is that it seems like whether it's just a little or a whole lot of flux, it melts to the steel and sticks right away. (I've been fluxing and reheating as soon as it drops below welding heat and I've done whatever strightening, etc. I need to do.)

It depends on what they look like in the finished blade, of course. Generally speaking, (and it's very general at this point, as this is only my fourth blade) I don't really go for a rustic look unless someone specifically asks me to do that for them on a project. Sometimes, it's okay though. If it looks like there is enough contrast to hide it, I may try to fill any cracks with weld and grind flush if it a matter of saving the blade, but in that case, it'll have to be for display only.

There might be some nickel in the blade I used, it's been sitting around for about 20 years. I'll use the above as an excuse not to fold it over any more, though!

I'm glad I asked about the etchant! Though now I'm going to keep this copper-plating idea in mind for future goofing off. Couldn't hurt to be able to plate small decorative mild steel stuff once it's formed if it looks even halfway decent.

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You don't know the re-enactors I know ;-)
Although there seem to be a few re-enactors that want something to look "olde". "Can you put a few dents in the blade to make it look real?"
The people from these times weren't unsophisticated, and liked nice stuff.
At the end of the day a customer is a customer ;-)
Regards Charles
Trevor Jones wrote:

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Chilla wrote:

Yeah. I know.
Never starve, when you can sell the customer what he wants.
I was not even thinking of the Renaissance wannabe lot, but rather the Buckskinner wannabe's. They would be a more likely audience, I think, for a little bit "rough" looking blade.
Cheers Trevor Jones
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Hi Prometheus,
I thought you would have done this before.
Oh well, I can offer some humble tips, if you're willing to listen.
I do chainsaw blades on occasion, but I'm not as fussy as you are, I just wire up the chain, get to welding temperature, in my venturi gas forge, flux with household borax (borax is borax, any water vaporises off anyway), chuck it back in for about 10-15 seconds, tap, tap, tap.
The main thing with chainsaw is to not overwork it, otherwise you lose the pattern, maybe 2-3 folds, but that's it.
Borax is an extremely aggressive flux and you will lose bricks, I will have to re-line my forge soon, but I will be replacing the lining with better refractories. The base of the forge will still be eaten by borax, that's why it's a good idea to have a sacrificial floor.
It doesn't matter how much flux you use, the bricks will still be eaten away... it just happens. Also you will find flux sprayed everywhere, no matter how soft you strike.
You want less oxygen, a reducing atmosphere, more gas, be sure to have adequate ventilation. Less air.
The small cracks well these sound like inclusions or cold shunts, heat it up flux it up and tap tap tap.
Sometimes metal wont weld, maybe too much sulphur in that piece of alloy, maybe something else wrong. Sometimes the faults can be ground out, sometimes the piece has to be scrapped.
Okay Ferric chloride is fine to use, straight, although I like to dilute it with water 4:1 acid water. Just a preference, the etch isn't as aggressive.
I always etch after polishing and heat treating. When you think about it doing it the other way around is a waste of time.
Neutralise the acid with bicarb soda and water, then I like to clean the blade with ajax cream cleanser, I then use a fine steel wool, then a very light buff with a loose mop with "no" tripoli.
The striking contrast that you see around the net is usually created by using nickel.
I've blathered on enough, and everyone that does this has a slightly different technique that they like.
You'll find one you like too :-)
Regards Charles
Prometheus wrote:

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Well, I'd reflux after every heat. I don't know anybody who doesn't. Most knife makers and pattern welders that I know do everything they can to exclude oxygen and keep impurities out of the surfaces to be welded. They usually use a LOT of flux. It's all over the floor and they get good blades. One of our young members noticed that the more flux he used in a gas forge, the hotter it seemed to be. He convinced his college prof. to let him do his thesis on it. Turns out that, as the borax "turns to rock" in the forge, it creates an exothermic reaction that can add as much as 200 F to the temp in the immediate area of the weld!
I think 20 mule Team borax has some soap added and that's what may make it poorer. Of course I'll get a lot of flames for saying so, but when you heat hydrated borax and it foams up, then it can drop off. I prefer to see the glassy spread of melted anhydrous borax on my heating joints. We all seem to have our own favorite flux and I have mine, but I won't tell you on this newsgroup because I don't want to hear all the arguments. You can call me if you want to find out. You need to see some forge welding done in other gas forges so you can see what the temperature LOOKS like. I agree with another poster that if you don't have some flame coming out, you probably have too much air on. Come on over and try to weld some chain saw chain up in my coal forge for reference. I haven't had the forge running for a while and I need to forge weld some iron from a recent smelt. The smelters gave me a bunch of thin plates (3 or 4 pounds) that they couldn't weld in a gas forge. I need to get that done anyway.
Pete Stanaitis ----------------------------------
Prometheus wrote:

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spaco wrote:

I'll bite, Pete.
What's your favorite flux, and where can we get a little?
My email addy is good, if you really don't wanna put it to the debatin' team, but then, how's a new guy gonna learn it?
:-)
Cheers Trevor Jones
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Trevor Jones wrote:

While you're sending info, my hand is up also ;-)
Regards Charles
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Okay, okay; so you've twisted my arm:
Centaur Forge Gas Welding Flux. I think its the one they now call "Climax Welding Compound", but I'd ask them before ordering. I probably wouldn't have ever tried it but several years ago when the ABANA conference was in LaCrosse, Wisconsin, I was one of the site managers and the demonstrator (who was making "powder damascus") suddenly informed me that he hadn't brought any welding flux and needed some RIGHT AWAY!!! So I ran to the registration building where several vendors were set up and bought a gallon can of the only thing they had and this was it! BTW, the can was only half full for $36.00 US. (Must have been sold by weight). Anway, that was a lot of flux. That demonstrator told me it worked well for him. It has a reddish tint, probably from some iron oxide. I have used it for most of my forge welding since then and I am almost out of it.
Around here we buy Anhydrous Borax in 55 pound (I think) bags every now and then. One of the guys, Mike Blue, has ordered up maybe a half ton or more a couple of times. Then folks buy in smaller quantities from him. He is a serious knife maker and uses a lot of the stuff. Several years ago, a friend and I bought one bag out of a half ton "purchase". I went to the local hardware store paint department and ordered 2 dozen new quart paint cans. We repackaged and labeled the 55 pounds into those cans and gave them away at club raffles, etc. I might still have one or two around.
Pete Stanaitis ---------------
Chilla wrote:

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spaco wrote:

Thanks Pete!
Can't say as to the likleyhood of it causing any consternation, though. :-)
Probably not.
Glad to get a report of something that works as advertised.
I know the old farts I used to hang out with would pack a lunch and stand around all day, for a chance at a box of, IIRC, Ready-weld at a farm auction, if there was some rumored to be there.
Cheers Trevor Jones
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