heat treat advice

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CTrelichunter

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Jul 11, 2020
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Hi guys I haven't posted much here. I recently got some Nitro V to make a couple fillet knives and some kitchen knives . I can't afford to get a dewer and LN. So I was gonna use dry ice . Can someone tell me how much dry ice and alcohol is needed for say 3-4 knife batch? and how long to soak in ice bath? Thank you I did a knife making class with Matt Parkinson from Dragons Breath Forge last weekend. I picked his brain. He uses pure grain alcohol with DI. curious on ratios alcohol to how much ice
 
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CTrelichunter said:
Hi guys I haven't posted much here. I recently got some Nitro V to make a couple fillet knives and some kitchen knives . I can't afford to get a dewer and LN. So I was gonna use dry ice . Can someone tell me how much dry ice and alcohol is needed for say 3-4 knife batch? and how long to soak in ice bath? Thank you I did a knife making class with Matt Parkinson from Dragons Breath Forge last weekend. I picked his brain. He uses pure grain alcohol with DI. curious on ratios alcohol to how much ice
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It depends on the size of knives and the container. I use a vertical tube with a 1.5l volume. For a batch of 20 knives @20min each inside, three at a time cycling, it's still 1.5l alcohol and 5-6 kilos of ice. Day before treatment i put alcohol in the freezer to save some ice. I take care that there is ice at the bottom so I know it's at temp. If you want to use a slurry, it's probably the same ratio but there is less refiling with ice. I like it liquid. Easy in and easy out. My container is plastic and foamed outside. Others may have different experience.
 
For a small batch of knives 3-5 pounds would be sufficient. I probably use half a gallon of denatured alcohol and 5 pounds of DI.

Break it up into chunks and add it to the alcohol in a small foam cooler or metal pan. You only need enough alcohol to cover the blades completely. Since you are doing a sub-zero cooling, all you need to do is cool the blades to the temp of the slurry - around -100°F. You don't need any long soak, but you can leave them in for 10 to 15 minutes to make sure they get completely cooled. Take them out and let warm up to room temp and then immediately temper twice.

The alcohol can be left to sit until all dry ice is sublimated and poured back in the can for re-use. Shake the can a bit and leave the cap slightly loose for a day to let the dissolved CO2 escape and then close the cap tight.
 
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JoeBusic said:
It depends on the size of knives and the container. I use a vertical tube with a 1.5l volume. For a batch of 20 knives @20min each inside, three at a time cycling, it's still 1.5l alcohol and 5-6 kilos of ice. Day before treatment i put alcohol in the freezer to save some ice. I take care that there is ice at the bottom so I know it's at temp. If you want to use a slurry, it's probably the same ratio but there is less refiling with ice. I like it liquid. Easy in and easy out. My container is plastic and foamed outside. Others may have different experience.
Click to expand...
thank you
 
I tried the vertical tube a couple of times with dry ice pellets and have had zero luck with it. The pellets always stuck together to the point where I could not get the blade submerged. I guess I would have to use a lot less ice and keep adding ice as it evaporates. I went back to a small cooler. I buy the smallest bag of dry ice they have, usually around 4-6lbs and make a slurry with about 3-4qts of alcohol. That will treat six 8" chef knives with plenty of dry ice left. If you do the cold treatment between plates to avoid warping, you may need more ice, depending on the size of the plates.
 
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