Need some help in using dry ice as a Cryo treatment.

BobbyD

Well-Known Member
So I want to start HT Aebl and would like to use dry ice for the cold treatment. Been searching around and can’t find much info on the recipe for the slurry mixture. I came across a post here that mention this:

“There can also be more error in DI slurry since it has to be made. Some folks don't add enough Dry Ice or Alcohol and also don't allow it the time to boil down to the coldest temp.
If the DI slurry is still boiling like when it's first mixed it's not at temp. You can also not add enough Dry Ice and it won't be cold enough.

Some folks don't always check the temp of their slurry to confirm, they just expect it to be "-130F"

So since I would like to be successful at this can someone please educate me to do it properly?
So far the closest place that sells it is 45 min away.
Thanks.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
I’d suggest RV antifreeze. It is nontoxic and pet safe. 5lbs of dry ice is more than enough for a couple blades. Use a small cooler, put the blade in, put in the dry ice and add enough RV to cover the blade, not all of it. Let it sit overnight. The antifreeze will freeze. It will get as cold as it can with any liquid. When it thaws you are done.
 

KenH

Well-Known Member
Boss, have you checked the temperature of the RV antifreeze 'n Dry ice? With alcohol 'n dry ice I usually get around -90 to -95F, and a few times a tad colder. Bust up the dry ice into smaller chunks (crushed would be nice) mix enough alcohol to make a slurry, and be sure to give it time to settle down without boiling and you'll have a nice cold temperature. Alcohol is easier for me to get than RV antifreeze, just a trip to hardware store (or walmart) and they've got plenty.
 

bladegrinder

Well-Known Member
I use acetone and dry ice and get a solid -100 degrees. here's my lay out...
I have a gallon of acetone just for this purpose because as I pour it back in the can there's usually some crap that found it's way in there, that way it's never used for cleaning blades of epoxy or any business like that.

I buy my dry ice at Publix supermarket, not all of them carry it though. usually a 6-7 pound bag I think.
I built a framed box that's filled on the inside with spray foam, then setting a large heavily greased loaf pan in it while the foam cured.
now the pan fits right in and out.

I use a large funnel to pour the acetone back in the can after it's back to room temp.
I know it gets hot everywhere but where I live it can be 90 degrees in November, the foam box made a WORLD of difference as to how long the ice last.

I can't explain why but the acetone has ' 0 ' effect on the foam, I've spilled on it a few times and it did nothing to it.
using a digital thermometer I've gotten -95 -100 in the acetone nowhere near the ice or any slurry mix.
I clamp my blades between aluminum plates in the bath and took temp. reading between them where only acetone was, no ice and got -100.

About the only thing I can add is when doing this procedure with acetone and dry ice you have to be careful thru the the whole deal and have all your ducks in a row as far as having everything laid out and ready to go.

I have pictures of the box I made and can post them if any one want's to see it, it made a world of difference in my opinion.
and like I said, the acetone didn't melt the foam.
 

John Wilson

Well-Known Member
A cool trick for the dry ice is to get a cheap little sno-cone maker. I buy a brick of dry ice from the grocery store and I bust it up into chunks with a hammer. Then I toss the ice cube sized chunks into the sno-cone maker and it shoots the perfect slushy-sized frosty chips into my cooler. Add the alcohol / acetone / whatever and voila. Put the blades in and leave them in there until all of the dry ice has boiled away. Pull out your blades and pour your liquid of choice back into the container. Like Steve says, I have a dedicated gallon can just for this because there’s always black, powdery residue in the alcohol. I don’t know if it’s from the dry ice, the blades, or if it’s from the dry ice wearing my sno-cone maker blades. At any rate I don’t want to use this alcohol for cleaning anything so it’s forever dedicated to the cryo can. (and my alcohol stoves when I go camping).
 

BobbyD

Well-Known Member
Ok so I have three blades to do. Do I use all 5-6 pounds and a gallon of liquid? Seems like a lot of liquid.
keep blades in till all ice is melted? How long does that take?
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
Boss, have you checked the temperature of the RV antifreeze 'n Dry ice? With alcohol 'n dry ice I usually get around -90 to -95F, and a few times a tad colder. Bust up the dry ice into smaller chunks (crushed would be nice) mix enough alcohol to make a slurry, and be sure to give it time to settle down without boiling and you'll have a nice cold temperature. Alcohol is easier for me to get than RV antifreeze, just a trip to hardware store (or walmart) and they've got plenty.

the temp will be the same whether it is acetone, alcohol or RV anti freeze. One doesn’t get colder than the others. RV antifreeze is cheaper than the others and isn’t flammable. I have also used acetone and kerosine. They both stink, especially kerosine. Acetone eats a lot of plastics and FYI will happily eat through a little playmate igloo cooler.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
Ok so I have three blades to do. Do I use all 5-6 pounds and a gallon of liquid? Seems like a lot of liquid.
keep blades in till all ice is melted? How long does that take?

use all the ice and just enough liquid to cover the blades. If you use acetone, plan on some of it evaporating.
 

Self Made Knives

Well-Known Member
I always use acetone. It's a chemical that I already have on hand and use for other things anyway. Once the dry ice has boiled off, just pour it back in the can. Not sure what kind of super foam Steve is using, I'm on my second foam box due to a little spill. My foam was just building insulation foam and it disappears instantly when acetone touches it, lol.
 
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