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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making. |
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#1
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Refractory Cement as anti-scaler
I'll bet this has been discussed before but I can't seem to find any info.
I have been doing searches here (and elsewhere) regarding the use of standard store bought refractory cement as an anti-scale/decarb coating versus ATP641 or thinned out Satanite. So far I have found nothing.....thus this thread. I looked on the web for specs/ingredients of Satanite and ATP641 and couldn't find much either. Even an MSDS on these would be helpful....without paying for it! I am wondering if the standard refractory cement/mortar that they sell in the big box stores could be thinned out with water to a thin slurry for knife blades. It is only rated to 2000F, but that would be fine for my usage on 1095. The only ingredient MENTIONED on it for safety reasons is "sodium silicate". Is this stuff similar to Satanite (that can be thinned) or is it a somewhat different compound? I could just purchase some ATP641 for about $15+ shipping/pint, but I'm already spending a lot on other things making a kiln and obtaining other tools/equipment, supplies, etc. I am attempting to save a few bucks where ever I can......the nickels and dimes are adding up too! If I have to purchase some ATP641 I will. Thanks, DAVID |
#2
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I know that people have used the Portland cement furnace patch to do hamons with and some start out with a very thing wash of the product to put like a base coat on the blade that servers like an anti-scale layer.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#3
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Hi Doug, thanks again for helping.
My local big box store has the Meeco brand of refractory cement and mortar. I don't know if that is a Portland cement formula or not, I can look into it more. I'm actually not sure how much scale or decarb I might encounter with 1095 HT but I'm sure it won't be too terribly deep. Either way, whatever amount is present without using a coating I would much prefer to use a coating and save myself some extra work and time finishing the blades. DAVID |
#4
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Actually, what I do to deal with any amount of scale build up on my blades is to soak over night in white vinegar then brush it down with a copper brush.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#5
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Doug, When do you soak with vinegar and brush with a copper brush?
Do you do this right after HT and before temper or later? I was going to clean off as much scale as possible right after HT and then put it right in the temper oven. After tempering I was then going to perform my final finish grinding, etc. I was under the impression that we are supposed to get that blade into the temper oven right away after HT and not wait as long as over night. DAVID |
#6
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I do it right after tempering. I don't want to delay getting the blades into the oven much longer that it takes for them to cool off to where I can hold them in my hands. There have been makers that have had blades break after hardening setting on a bench while they austenized and quenched other blades.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#7
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Doug, I'm glad to hear you are doing that vinegar soak AFTER tempering. I've read all about the need for tempering right after HT.
I might be playing with some vinegar forced patina down the road, but I wasn't planning on using vinegar specifically as a cleaner after tempering as you are. Do you encounter any decarb pitting or just scale when you HT your 1095? Do you have just a minor amount of finish grinding/sanding to do? I realize there will always be finishing to do (and I want to), especially if I leave my blade edge a little thicker for HT. But.....I would really rather avoid as much scale formation as possible and don't want ANY decarb. I would prefer to just coat my blades with something that won't cost too much. I heard that some people have used Ivory soap, Dawn dish detergent (dried) or soot from an acetylene torch (O2 turned off). How well any of these less expensive home brews work I'm not sure. I realize they are just used to keep the O2 off the blade. I do NOT want to add any special system to my kiln to create special atmospheres. My elect. kiln will be fairly air tight.....I read that some people have added a piece of charcoal to their fairly air tight elect. kiln to help burn up the O2. How successful that is I don't know. DAVID |
#8
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First of all I no longer use 1095 as all that I have for heat treating is a propane forge and I feel that I would be better off heat treating steel that has 85 points of carbon or less to avoid building up retained austinite. You, on the other hand, are building a regulated electric oven that can handle austenizing steel under regulated conditions. So that gives you a leg up on me.
Another thing, I'm a smith so I'm routinely heating my steel up above 1600? so I'm just going to get scale formation during the forging process. However, I don't seem to get much austenizing the steel while looking for the decalesence to pass and then soak for about a half minute using something like 1084. Nor do I run into problems with pitting. I also think that worries about decarberization are a little overblown, especially if all you are austenizing steel for is to harden it. Now, if you were getting the steel up to welding temperatures, 2200?-2300?, for extended periods, yes you are going to have problems with decarberization. As far as whether it's better to prevent scaling while austenizing or removing the scale later, it's up to you. I tried a powder to coat my blades to prevent scaling while austenizing for hardening but the compound seemed to be as much trouble getting off as soaking in vinegar. I needed to boil it in water and there still was a little that I had to take off with a grinding belt. Some just clean it all off with a grinding belt but they probably go through belts a little faster as scale can be a little hard on them. Doug __________________ If you're not making mistakes then you're not trying hard enough Last edited by Doug Lester; 01-24-2016 at 10:53 PM. |
#9
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White vinegar is readily available, cheap, easy, and enviromentally safe - plus you can use the residual to blacken leather, stain antler, and darken some woods. What's not to like?
__________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#10
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With all due respect: Like I said, I would prefer to avoid any scaling in the first place with an anti-scale coating. Doug is using vinegar to clean the scaling off blade.
I will be experimenting with vinegar later for a forced patina. Therefore, I still wonder about the "home brews" of anti-scale compounds. Does anyone have any info or experience with the home-brews I mentioned? |
#11
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One of my friends in the GA Guild uses a liquid dip to coat his blades prior to HTng to prevent scaling. I'll ask him what it is (do know it is a bit pricey).
__________________ Carl Rechsteiner, Bladesmith Georgia Custom Knifemakers Guild, Charter Member Knifemakers Guild, voting member Registered Master Artist - GA Council for the Arts C Rex Custom Knives Blade Show Table 6-H |
#12
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Hey David,
I have only been doing this for six months, and I did the same thing you are about trying to save everywhere I could to get started. I too built my own oven out of an old cappuccino machine thrown out by a convenience store. Works great...sorry...getting of topic. I finally just decided to buy the ATP from brownells and I'm super happy with it. It works great. I know exactly what you mean about the nickels and dimes adding up. It's crazy how fast it all adds up. Hope you get those "home brews" figured out. I'll be checking back, if there's a good one I may give a it a shot too. Best of luck. |
#13
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Thanks walterwhite.
The first thing I will be trying is Milk of Magnesia.....the old original white formula. I have some nice info about it and mentioned it in the heat treat procedure thread I have going. DAVID |
#14
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Really Milk of Magnesia? I've never heard that one. I'm going to have to google it up.
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#15
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I found the info on a sword forum and elsewhere.
I believe I posted the more specific properties of it on another thread I started regarding Heat Treat Procedure on this sub forum. The original white formula Milk of Magnesia is Magnesium Hydroxide (MgOH2) which is Magnesium Oxide combined with water. When it is heated over 660F it releases what water is left (after drying on blade first) and decomposes to Magnesium Oxide (MgO). Magnesium Oxide (MgO) is a good refractory with a melting point of over 5kF degrees. I will eventually be trying it. I intend to apply 2-3 thin coats to diminish cracking, letting each coat dry. |
Tags |
1095, art, bee, blade, blades, brand, build, coat, forge, forging, grinding, helping, ivory, knife, makers, making, ore, quenched, scale, sell, store, supplies, temper, tools, white |
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