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I Forge Iron

Preventing oxidation


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Howdy folks,

I have been working on a drop point blade for a friend and the process got me wondering. Many have dealt with the effect of heating iron and the clean-up required to remove scale to the various desired end look of the project. After alot of reading I found mention of a coating or two as a barrier to free O2/iron. Metalbrite and one from Casenite that slips the mind. Further searching didn't produce and makes me wonder if these products are still made?

With more general sorts of projects I suppose it didn't matter to me so much, but blades may have a mirror finish. It would also make sense to adjust burners for the cleanest burn if not for the oxidation problems? Any thoughts?

Thanks Dave

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This is out of my field of specialty, but perhaps I can pave the way for some of the more knowledgeable folks to post by getting things clear first.

Are you talking about heating the blade for forging, or only for heat treatment (HT)? If its post forging, but pre-HT, you can really go to town on the scale without worrying about overheating. And if you do a mirror finish, thats going to be the last thing you do to the blade (post-forging, post-basic grind, post-HT) so where does fire-scale become a problem?

Are you suggesting putting a coat of one of those products on it before heating it? If so, it seems pretty likely it will just burn off, doesnt it?

Also, yes, setting your fire (gas or coal forge) to be "fuel-rich" or "reducing" is important if you are worrying about scale (oxidation). Again, not sure if we are talking about heating for forging or HT, so its hard to advise.

If you are forge welding the blade and therefore getting heavy scale, you might find it handy to water-hammer.

Perhaps there are some people who are familiar with the products you mentioned and can explain how they work. Could be I am missing something here.

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Thinking out load about oxidation in bladesmithing. Some have warned to forge in the least number of heats, not to allow scale to be forged into the surface ect. One gentleman would borax fine model pieces prior to forging heat to avoid oxidation problems. I do understand the methods to minimize the effect and clean-up of what occurs. Since many coatings are used in industry at these temperatures for a variaty of reasons it would make one wonder if there is a coating for this purpose? If not it was worth asking anyway.

Thanks Dave

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There are a few different options to avoid/reduce scaling and decarb durring HT. One common method is to use stainless steel foil to make a pouch to put the blade in. You can purge the pouch with an inert gas or, stick in some thing combustiable in (like a bit of some paper) to remove/consume the oxygen in the pouch.

Also, If you use a high temp salt pot for HT you wont have to really worry about scaling or decarb. Since the blade is heated in molten salt, it is never exposed to oxygen durring heating to cause any scaling or decarb.

That or a fancy electric HT oven that is perged with an inert gas.

However, since this was your main concern, there is a specific coating designed especially for heat treating. Its called Turco pretreat. You dip the blade into the turco, let it dry, then proceed with with the HT. The turco protects the blade from any contact with oxygen. I don't know its max working temp, but I know it works in the ranges for HT for blade steels. After the HT you can either clean off the turco with a bit of sand paper or with some type of solvents. I havent ever personally used it so I cant give you all the details, but I know its out there. I think awhile back I remember Rich Hale mentioned that he uses it and can probably give some more details. You can get a quart of it for about $40 from knifeandgun.com

I havent heard of metalbrite or the other.

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Thanks for information,

For what it is worth Turco appears to be a max. 1900F shielding product using Toluene/MEK as a carrier. Ceram-guard I believe so far to be a water based similar product. Used in industry to protect tool dies from oxidation pitting as well as HT applications.

Thanks again for the research leads


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