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I Forge Iron

Prep for claying?


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Hi everybody,

I've been a knifemaker for a couple of years and I decided to try my hand at forging plus my daughter is interested in learning as well.

I got this forge from my uncle and I was wondering if I should remove the rust from the pan before claying it. It seems like the right thing to do but I didn't know if it was necessary. Thanks!

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Welcome aboard, glad to have you. Does the pan have "Clay before using" cast in it? If so then just brush the loose rust out and ram DAMP sandy clay mix into it to a thickness of an inch or better. You want it only damp enough it'll ram up hard, a wooden mallet is perfect. If you mix it like plaster it'll shrink check as it dries just like the bottom of a mud puddle. A mix of 2pts sand to 1pt clay works well, the sand allows moisture to escape and moves with expansion and contraction and helps prevent heat checking. Some guys have good luck mixing ashes to the mix as well but I don't know the amount.

If the pan doesn't say clay before using then I wouldn't. Clay can trap water against the pan and increase rusting.

Frosty The Lucky.

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Thanks for the welcome Frosty! Yes, it does have clay before using stamped in the pan. I already have some clay mixed up ready to go, so I wanted to make sure I'm doing it right. Thanks!

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Your welcome. Just damp enough it clumps if squeezed hard in your hand and it'll ram up hard. Once rammed hard smooth it off, less clinker will stick to it and it won't gouge as easily when you poke it. Leave a depression around the air grate, this is called a "duck's nest" and acts like the fire pot. However it's a darned small and shallow fire pot. You can mound coal up around it and it'll work fine or you can arrange bricks around it to make any shape or depth fire you need.

Duck's nest forges are my preferred coal forge. Be advised however I rarely burn coal or charcoal I'm primarily a propane forge guy. ;)

Frosty The Lucky.

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OK, so my clay was a little more damp than I thought because when I tried to ram it, my mallet kept catching instead of bouncing off so I just tried punching it all down by hand then I smoothed it. I got the whole thing clayed to a depth of about an inch and the "duck's nest" is about 1.75" deep and 6 inches across at the top. How does this look? Is there anything else I should do? I was thinking of letting it dry overnight and trying to ram it again, should I do that?

Thanks for the help and sorry for all the questions!

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That looks good. You have a couple options. Let it dry, shrink check, or score it and use it. The forge will last hundreds of times as long as the clay. You can let it dry a while and ram it down again it won't hurt, might help. You can lay a burlap bag or cardboard, etc. on it and ram it again. The cloth, cardboard etc. will pick up the free moisture when you hit it and draw moisture from it fairly quickly. You can spread a layer of dry sandy clay on it and ram it into the existing liner. Do it in between 1/4"-1/2" lifts this will dry the liner much more quickly and make it thicker.

I'd score it, let it dry a while and use it as is. "Scoring" is cutting grooves in the liner to control checking by providing EASY lines for it to crack where you want. You see scores in sidewalks, the graph pattern between expansion joints. Just use a butter knife or similar unsharp blade pinched with say 1/2" extending beyond your fingers and score a pattern. When I used my rivet forge I scored it in a spider web pattern, six lines radiating from about 2" out from the duck's nest with scores crossing the wedges. . . Like a spider web.

None of this is a requirement this is just what worked for me in the short time I used a clayed rivet forge. It's not a rule to ram it up barely damp, burnish it, score it or even clay it. Just remember what you did this time and how it works. The ONLY thing that really matters is a working forge.

NO need to apologize for good questions, especially when you think about the answers, give them a try post a pic and show us how it turns out. Yours are the kinds of questions and responses we live for.

Frosty The Lucky.

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Thanks again Frosty! I am definitely going to score it. I agree that a working forge is really all that matters and my daughter is anxious to get going. 

I do have one last question: I've seen most people say to build a small fire in the forge after it has dried. What kind of fire (coal? wood?), how long should it burn and should it just be in the firepot? OK, I guess that was technically 3 questions.

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You're welcome, give your daughter a big warm Frosty hug for me. :)

I don't know I always rammed mine up with a moisture content you'd use for green sand casting so I didn't need to let it dry long.

I suppose you could speed initial drying with a fan and or maybe a couple light bulbs hung close over it. Say till it feels dry and you can't make a dent with a finger push? Then I'd start out with a  modest wood fire and just let it burn without blast. Let it cool and see how it reacts and do it again but bigger and give it some blast. The only place it's going to get really hot in use is directly under the fire so figure the ducks nest and maybe 3-4" around it are going to get darned hot.

Just take it in a couple stages then let it rip. If it falls apart it's just dirt, ram it up again. Be sure to take pics and we can brainstorm through failures.

Frosty The Lucky.

 

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  • 3 months later...

Awesome...just what I was looking for. I bought a forge from a semi-local "dealer" and it has "Clay before using" cast into it. I have some clay/ sand mix from a construction buddy that I will use. It's in a plastic tub outside so right now it's mush but I will pull some out to dry a little before I need it.

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  • 2 weeks later...

I started claying my forge today. I am using regular construction clay given to me by a buddy. It is basically some grey and red clay with some sand mixed in. I may try to add some more sand in the final layer.

The clay was a little too wet due to rain but it dried pretty quick as I worked it. I spread out a layer about half an inch thick and worked it in by hand, then with a small piece of RR track, then with the mallet and dead-blow. I let it dry for about five hours and the came back and pounded it again. I had some cracks and some soft spots. This layer is probably 1/8" - 3/16" thick now after pounding it in four times. Tomorrow, I will add another layer and make it a little thicker.

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Comments and suggestions welcome.

 

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2-3 pts. sand to 1pt. clay. just enough moisture you can squeeze it into a hard lump in your hand and ram it in with your mallet though the piece of rail makes a nice finish. Just go with one lift and try for a finish thickness around 1". Don't mix it to mud, even barely mud or it'll shrink check as it dries like a mud puddle.

Claying a forge is a wear item, it isn't going to last long, weeks, maybe a month or two depending on how much you use it, how wet it gets, how many cats are around. You know the usual. ;)

The only purpose of claying a forge is to disperse the heat from the fire, cast iron doesn't like high differential temperatures or the thermal shock of a splash of water when hot. The clay is to help prevent it from cracking do to heat stresses. It's just dirt replace it as necessary.

Beautiful forge, nice score.

Frosty The Lucky.

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On 8/14/2016 at 0:52 AM, Frosty said:

Claying a forge is a wear item, it isn't going to last long, weeks, maybe a month or two depending on how much you use it, how wet it gets, how many cats are around. You know the usual. ;)

Very true. And the higher the clay content of your mix, the more it will vitrify and stick to the clinker. My own forge is about due for re-claying; thanks for the reminder.

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It will crack it's not a big deal. The purpose of dispersing heat more evenly is served cracks or not. If you ram it in as wet and clay heavy as yours is, score it with a butter knife to control shrink checking. Just make some shallow "cuts" with a dull knife, the clay will shrink check in the cuts where you want it to rather than where ever shrink stresses overcomes the strength of the clay. I liked a spider web sort of pattern radiating out from the fire with 2-3 round scores connecting them. The liner checked nicely without large gaps.

Once your liner checks just sprinkle some dry sandy clay in the cracks and it's golden.

Frosty The Lucky.

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