Cooler: Rock Salt PLUS DRY ICE? Would it work even better?

maryvmcclain

It sounds like many people are coming to Powell with portable freezers this year. We are going to "rough it" with our existing Norcold frig (and solar panels) and a cooler and the generator. We are going to try the rock salt and ice method of packing described by several people here (double sealing food in freezer bags and with a separate tupperware container for our drink ice cubes.

We are also attempting to make a reflective cover for the cooler. Its supposedly a 5 day cooler but we can tell you it never lasts more than 3 days.

I know dry ice is dangerous (especially for eggs) and I think I remember that dry ice doesn't have the same chemical reaction with salt that plain ice water has? But, would it help to put some dry ice in (perhaps at the bottom or at the top) and then have the layers of regular ice and salt?

I am thinking the dry ice would keep everything cooler and keep the ice from melting, but obviously, I doubt the dry ice would last the whole time we're there at Powell (assuming we can find some in Page AZ at the beginning of the trip.

I'm sure everyone has tried everything with regard to keeping ice at Powell so dry ice improve performance? (I really hate those 50 mile trips for crappy ice but this is the best option for us so close to leaving for our Grand Slam trip) Eventually we'll invest in the freezer/frig and take out the existing Norcal

Thanks
Mary

A vendor should run a floating barge with an ice maker that goes up and down the lake... seems like a great business opportunity for someone!

Sunbeam · Posted: Wed Aug 19, 2015 6:58 pm Post subject:

I can't speak to dry ice (but I imagine others can), however I was okay on Powell for the last three trips with just a cooler and buying ice at the marina stores. I put a LOT of ice in when I did buy it, and I kept a constantly wet towel over the top of the cooler (evaporation). The other thing I did was keep things like produce, butter, cheese, etc. (things that really only need to be cool not ice cold) in a bucket. I put a little water in the bottom of the bucket, and then a wet towel over the top (that I re-wet in the lake when it dried out). This kept lettuce, cheese, etc. surprisingly cold. If I had a second large cooler I could just have used that, but I only have one. On the other hand, as I used things up, I didn't have a second huge bulky cooler to contend with.

I learned when sailing (only had an ice box) that many things don't really need the "ice cold" refrigeration we give them. However I DO like cold drinks and cold milk for my coffee, so that's mostly what I kept in the ice-cold cooler.

I stayed out nearly a month on the one trip, although I don't think I ever went more than around 7 days without buying ice. So this wouldn't apply to staying out weeks away from the ice store (at least not and maintaining cold food). In my case I was okay with hitting the ice store around once a week.

Maybe dry ice would be even better - I have never used it. But figured I'd mention how I "stretched" my regular cooler in case it might help.

Sunbeam

PS: This past year I had an "ultimate extreme" (IIRC) 6-day 58 quart cooler, and it does work better than the one I had the previous years, which was more run of the mill. But the main "trick" was the use of water/wet towels to supplement.

thataway · Posted: Wed Aug 19, 2015 7:31 pm Post subject:

My experience with Dry Ice (solid CO2 - 109* F) has been in long distance races such as the Trans Pac or some of the Mexican races and river rafting. We used it only for frozen foods. Wrapped the dry ice in paper, and kept it at the top of the box. You need heavy gloves to handle the dry ice.

Dry ice has been available at the WalMart in Page, and also Reddy 2018 E Frontage Rd, Page, AZ (Reddy ice supplies the bad ice we get on the lake!)…

There are some issues with dry ice and ice chests. It may freeze everything in the chest. It may crack the plastic in the ice chest. (Be sure and wrap it in paper). The ice/salt mixture, will have a lower freezing/thawing temp than regular ice.

One trick is to put the dry ice (wrapped in paper) at one end of the box, then a block of ice, and finally the foods. I don't know if this will prevent freezing the entire box--but it probably will.

We use the styrofoam 1/2" material sold at Home Depot, which has foil on both sides. We put this on top of the freezer/refer, and then cover with the wet cloth/towel. If you have a freezer/refer with a compressor, then be sure and allow ventilation for the cooling air circulation. We use a foil covered insulating "blanket" which fits the refer/freezer, and gives extra insulation. We only have one of these, and will probably make a surround for the second box, using the foam boards.

A lot depends on how long one stays on the lake, and how far from "ice" one is. We will see how our experiment with all electrical works out...

ssobol · Posted: Wed Aug 19, 2015 8:12 pm Post subject:

One thing with dry ice is that it sublimates not melts. When regular ice melts there is ice water left behind that can extend the time of useful cooling (for things that should be cold/cool but not not frozen). The water also helps conduct the cold better because of the high surface contact with whatever is being cooled.

Dry ice just turns into CO2 gas and dissipates.

With water ice you do have to protect the cooled items from getting waterlogged though.

If you mix water and salt into solution and freeze it you have ice at a colder temperature than normal ice. I doubt you can get rock salt into solution with CO2. Also, the water/salt solution freezes only a few degrees colder than pure water (depending on the salt concentration). Dry ice is already way colder than that (by a couple hundred degrees), the salt won't make any difference.

If you have a well sealed cooler you might burst it from over pressure as the dry ice evaporates (see dry ice bomb).

jimicliff · Posted: Thu Aug 20, 2015 7:44 am Post subject:

The problem with dry ice is that it does freeze everything, I have used it to prep the cooler the day before and it's pretty good for that if you don't mind the effort. I don't have problems with ice because I need fuel and 90% of the time there's ice too.

AstoriaDave · Posted: Thu Aug 20, 2015 11:10 am Post subject:

No, rock salt slurried with dry ice would not produce a lower temp. Only works if the added substance dissolves. Salt won't dissolve in solid CO2, nor in liquid CO2. The latter, held in a high pressure tank, is the form chosen by some brewers to carbonate beer prior to bottling. Shake a CO2 fire extinguisher sometime and you can feel the liquid CO2 sloshing around inside. Comes out as a snow of dry ice as it reaches atmospheric pressure.

Now there's a thought: As you pack the cooler with goodies, lay on a loose layer of CO2 snow over each layer, to quick cool stuff without freezing the bejabbers out of it. The CO2 will dissipate, and you can supplement with ice as needed.

thataway · Posted: Thu Aug 20, 2015 1:02 pm Post subject:

My interpretation of the OP, was that she wanted to make a water/rock salt mix, and then use the dry ice to freeze it--which I believe would occur at a lower temperature than "pure" water ice. So perhaps Mary can let us know how she wants to pack and maintain the ice chest.

RobMcClain · Posted: Thu Aug 20, 2015 2:43 pm Post subject:

Hi folks,

What Mary was asking about pertains to doing a mix of regular ice & rock salt, mixed with sealed food. Then putting a small wrapped layer of dry ice on top of that mix (placed in the top of the cooler) simply to keep the cooler colder longer. The idea is to hopefully allow the normal ice & rock salt mix to last longer, thereby decreasing the number of times we might need to refresh that mix by pulling anchor and cruising to a marina to buy new (often poor quality) ice. We are planning on using the cooler just for items we want to generally keep frozen.

Rob (& Mary)

thataway · Posted: Thu Aug 20, 2015 4:18 pm Post subject:

Rob, the other question is how long will you be on the lake? How good is the ice chest? Is it a chest, with really good seals (or double seals, which potentially lead to pressure issue with the dry ice) , 2" thick insulation etc, vs a chest which has 1 inch and no gaskets?

Have you tried this chest in hot environments like Powell?

If you are going to try and keep food frozen for a couple of weeks, I would say that it is going to be difficult, with out a compressor driven freezer. For a week, you probably can do it with the dry ice. But, I wonder about how durable even the double sealed freezer bags are? (Water intrusion).

Common wisdom is that dry ice sublimates at a rate of 5 to 10 lbs a day in an ice chest. So lets say that in a week you will need 40 lbs of dry ice, maybe more.

RobMcClain · Posted: Thu Aug 20, 2015 5:57 pm Post subject:

All good questions Bob. We found at Powell the cooler would go ~48 hours before needing to be refreshed. I suspect we will forgo the dry ice idea. Even for just a quick cool down it doesn't seem worth the effort. Our cooler is a Coleman Marine Extreme 51 quart. It seals nicely and has thick walls, but ice hasn't lasted as long as we had hoped (and certainly not close to the advertised 5 days). Of course, who knows what their test environment was - certainly not the hot Desert. We've just made a nice insulated blanket for the cooler using an insulated reflective material, thoroughly covering all 4 sides and the top. We will test it during our upcoming lakes swing, with the big test at Powell. We're hopeful we've added at least a day to the ice routine.

Rob

Sunbeam · Posted: Thu Aug 20, 2015 6:41 pm Post subject:

I'm thinking maybe the reason I had such good success with being able to go a number of days is because when I get ice for the cooler, I FILL the cooler with ice. Yes, I do leave a bit of room for drinks and milk, but it's a lot of ice vs. mostly food with some ice around the edges. Then I put the "larder" temperature stuff in the separate bucket with a touch of water in the bottom and the cold/wet cloth over the top.

After a couple of days, I usually have room to move the bucket stuff into the cooler (but I almost don't need to as the bucket keeps things really cool). I also pre-cool any warm things I'm going to put in the cooler (typically beverages) in the "cold bucket" and that helps a lot.

I mention this because my cooler the first couple of years was decidedly down-market (although I did have the marine ultimate extreme last year) (good thing as being solo I was happy to "escape" having to dock more often for ice!). And yet I've always been able to go well more than the two days you mentioned (more like 5-6 or...).

Larry Patrick · Posted: Thu Aug 20, 2015 6:57 pm Post subject:

Just ran into this problem. Catching fish on our Erie trip wanted to come home with fish wasn't sure how long they keep on ice? Searched for dry ice no luck,place was out of it. Considered buying small freezer keeping it on dock covered incase of rain. Then forecast called for bad conditions so came home after 4 days. Thinking of better ideas for similar trips and trying to keep a weeks catch of fish. Maybee a dometic cooler ? Space is certainly a concern with boat space limited.

thataway · Posted: Thu Aug 20, 2015 7:19 pm Post subject:

Sunbeam · Posted: Thu Aug 20, 2015 8:02 pm Post subject:

True enough; last year I was not able to launch until just when the gang was taking out. Although that said, the first two years I was on the lake when the group was. I did stay later, but I was there during the get-together along with everyone else, with my cooler and ice.

I think it probably comes down to the fact that I have a very large proportion of ice to cooler space and then use a bucket for larder stuff (i.e. 50º is fine). Likely it's more common for folks to have more food and less ice.

I wasn't trying to say I had performed any miracles; just that I never had to get ice every two days as the OP's mentioned.

With any luck this year I may be able to try my Dometic cooler-style refrigerator, but if not I won't be too crushed to do the ice again (now if only they had real blocks and not "fake blocks" life would be beautiful).

Hunkydory · Posted: Thu Aug 20, 2015 8:51 pm Post subject:

My experience with the Coleman marine extreme cooler is similar to Sunbeam's & I set it up near the same also. I generally start out with a combination of square 1 gal frozen plastic water jugs, tightly joined with block ice & then all other spaces packed with cubed ice other than the small amount of space used for perishable food & a small amount of drinks. As the water jugs thaw we use them for drinking water & replace them & the block ice on the lake with the poor cubed ice available there. With keeping wet white towels covering the cooler, the first five days plus some, go well. We have never stayed more than 11 days, so have been able to get by with only an additional 4 bags of ice for that time period. The sooner the poor ice is added before the original jug & block ice melt, the longer it will last.

One year I found dry ice available & added 10 lbs to the side away from the food & on top of a jug, so to stay out of the melting water & it did prolong the original other ice life, but I can't remember by how much.