container for dry ice treatment

Hello all - I've used a dry ice slurry on a few blades now, and with using AEB-L it seems to be pretty important. I'd like to make a container to hold this slurry for sub-zero treatment of blades. My thinking is to make a wood container, perhaps wood/joints sealed with epoxy?

question #1: Do you think the epoxy will crack to bad and not seal at -95ºF? With good wood fit, sealing might not even be required - after all, blades won't be held very long. Other methods to seal wood/joints suggestions?

Question #2: What shape should this container be? If using a flat type container, (6"W X 4"D X 15"long) the blades will be laying flat, and AEB-L blades WILL wrap just lying flat. The seem to need to be held up on edge, and with the large open top of a flat container isn't the most efficient shape. The same 6"X4"X15" container, if made as a vertical box to hand blades vertically seems like it might be the best shape to help prevent wrap and more efficient to hold dry ice slurry longer.

I would like comments from ya'll as to which shape is best, and comments on suitability of wood to make a container from.

Ken H>

Ken, before I got my LN dewar and was still using dry ice & alcohol I used one of those little 2 liter drink coolers with the lid removed. If you're worried about warpage you can suspend them from a wire.

Here is the little insulated box that I use for my dry ice, sub-zero treatment. It's made from a sheet of polystyrene insulation board, fastened together with the handyman's secret weapon, duct tape. I know many use a liquid slurry for this type of process, but I've found that simply crushing up the dry ice and embedding the blades between layers of the "snow" produces great results without all the hassle of dealing with acetone or glycol.

Steel is a great conductor of heat, so the entire blade will equalize to the temperature of the dry ice, which sublimes (changes phase from solid to gas) at about -110 F, whether it's suspended in a fluid or buried in dry ice snow. Bottom line, I see no benefit to the liquid slurry over the simple way I do it. Just my 2 cents worth.

Brandant - have you put a temperature probe in with your crushed dry ice to check actual temps? It might be enlightening - with crushed ice there are MANY air spaces however small they might be, there are still air spaces and air is a good insulator.

The idea of a 2 liter cooler would work just fine - "IF" I can find one that's tall enough, right shape, etc. I think I'll ride over the WalMart and check to see what they've got. MUCH better idea than trying to make one. Thanks,

Ken H>

You might try using a typical plastic insulated cooler with RV non-toxic anti-freeze for the solution. It's nonflammable. It gels up but doesn't freeze solid in dry ice. You may have to thaw your blade out of the semi-solid antifreeze which is trivial.
I would be surprised if epoxy held up under those conditions. The metal is really going to move when it's that cold.

Obviously you have a source but for others, many (most) welding gas supply houses sell dry ice. Our's here charges $2.50 per pound I think. 2 pounds will last 6 to 8 hours in a cooler.

Darrin's idea of a 2 liter cooler was just right (Thanks Darrin). Went to WalMart and found a 1/2 gal size that's about 4" ID and 10" deep. While I'd liked just a bit larger (deeper?) I think this will do just fine as the tang of a blade doesn't need soaking, and this should work just fine.

Interestingly enough, one of the local grocery stores carries dry ice, and I think it's about $2.50/lb.... in that range anyway. I use Denatured Alcohol to make the dry ice slurry. Doesn't freeze until -172ºF or so, and at -95ºF it's quite happy liquid. Once the dry ice goes away, the alcohol gets poured back into container for next time.

Later

You're more than welcome Ken. Now that I think about it, I believe that a piece of 3" or 4" heavy wall PVC sewer pipe with a cap on the end would work great and you could cut it any length you could possible need. You could build a wooden box slightly bigger than the pipe and fill it with that foam that comes in a spray can.
A cooler is much easier but if you really needed the extra length that would be a pretty cheap and easy way to get there.

I use a long stainless steel pan, the kind they use on buffets. I got it at a restaurant supply place for around $6-7 I think. I just sit it on a piece of styrofoam insulation. They had lids for them too, but they were about same price as pans, didn't really think it was needed. To keep blades vertical, I bent up taco holder looking thing with some copper wire. I use grocery store dry ice and acetone.

Good ideas all, but Anthony - that acetone is messy stuff. I'm not known to be "overly" cautious, but denatured alcohol works just as good and is MUCH safer.... perhaps a tad less expensive when it comes time to replace?

Ken H>

Yeah Ken, acetone is seems to draw a lot negativity. I've always had it around for epoxy cleanup and its never seemed to be a problem. To me, it doesn't put off any fumes at -100 degrees, but my shop is big and well ventilated. If I ever empty this 1 gallon can I'll give the alcohol a try.

Like you Anthony, I've used acetone for many years with epoxy 'n polyester resin and never thought too much of it, just be careful with the stuff. Now in my "old age" I tend to be a bit more cautious. Since I tend to work inside (heated 'n cooled) for HT'ing and tempering I like the alcohol better.

Ken H>

I got an expanded polystyrene "cooler" (like the cheap '70's beer cooler) used to transport temperature sensitive drugs. I's 2" thick with a good form fitting lid. I discovered that the denatured alcohol would leak through the walls, so I painted it with several coats of paint I had laying around. Can't vouch for whether the paint will hold up to the cold temps, haven't used it since the paint. Prior to the paint job, though, I just lined it with poly sheeting, that worked too.

As for a source, I got mine from the in-laws, but any place that transports medications should have them. I got a second, larger one, from my veterinarian.

Good luck

-Kurt