DIY Cooler (Part 4) Analysis

Flex Seal:

  • Pros
    • White. Smooth(-ish) surface. Looks like it would be easy to clean
    • Food safe, so in theory you could drink the meltwater as long as it wasn’t fouled by whatever else you had in there
    • Cheaper, though maybe not so much if you had to add more layers for durability
    • Easily repaired
    • Easier to ensure is water-tight
    • Good thermal performance. Thermally equivalent to Line-X
  • Cons
    • Stinks when drying. Long application time (each surface has to be horizontal until set up or it will run
    • Two coats are substantially less durable than Line-X or a MIE cooler


  • Pros:
    • Extremely durable. Looks nigh-indestructable
    • Good thermal performance. Thermally equivalent to Flex-Seal
    • Application is quick (by others), nearly instant dry time
    • FDA approved for “incidental food contact” and potable water
  • Cons:
    • More expensive than Flex-seal
    • Granulated surface may be harder to clean
    • Need extra attention to ensure surfaces will spray water-tight (tape on joints?)
    • Thickness of spray may be inconsistent and need trimming for final fit
    • Overspray may be a problem on finished product. Recommend delaying finishing of box to allow for sanding if necessary
    • Base color is black. Think they can probably do white or other colors, but not sure of cost difference


On almost all counts, Line-X is at least equivalent to Flex-Seal, and Line-X is clearly superior in terms of durability. Most of the cons for Line-X are either acceptable or are easily compensated for. The only situation where Line-X doesn’t beat Flex-Seal is cost. For this experiment, Line-X was maybe about twice as expensive as Flex-Seal. I’m not sure what that cost differential would be when scaled up to a full size box, it may be roughly equivalent. On the whole, though, I suspect that when going through the effort to hand-craft a wooden ice chest, it’s probably worth the extra cost for a fully-assed end product.

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DIY Cooler (Part 3) Results


Cooling Performance Test: Boxes were placed in test area (the basement on a concrete slab) and allowed to acclimatize overnight. 3.5 lbs of ice were put into each box. Environmental temperature was not recorded as it should be constant for all and not relevant to comparative results.  Note: boxes were located near an operating ceramic kiln so air temperatures were quite high for a basement environment.

Durability Test: A full (unopened) can of soda (at refrigerator temperature) was dropped, bottom side down from 36″ into the container (at room temperature)

Test Subject #1 – Flex Seal

Cooling performance: All ice melted in less than 68 hours

Durability: Bottom of can hit at a slight angle and caused 1.5″ semi-circular tear lining, dented insulation beyond

Test Subject #2 – LineX

Cooling Performance: All ice melted in less than 68 hours. Note: Line-x spray was not water-tight and melted ice leaked into container and onto floor. After 24 hours remaining ice was put into a bowl inside the box. Not clear if this affected results. Heat gain due to loss of cold water was probably partially offset by reduced surface contact of ice alone against the inside lining.

Durability: No effect on lining. Slightly dented bottom of can

Control – Plastic Cooler

Cooling Performance: All ice melted in 27 hours

Durability: No effect. Can bounced, almost out of cooler. Suspect that plastic lining may have cracked if can was much heavier or dropped from higher.

Read on…

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DIY Cooler (Part 2) Proof of Concept

How do we test this idea without spending a ton of time and money on making a box that may ultimately be a complete failure?

Cardboard mockups!

Using $1 boxes from a local big box store. We could have used leftover shipping boxes, but for scientific comparison, we needed identically sized boxes. Each, lined with 2″ foil-faced iso insulation.

Test subject #1: “Flex Seal”

This stuff is about $30/pint and it looks like one can will coat about 1.5-2 boxes this size. Note that, despite the label, this is not pourable/dipable. It is too thin to cling to vertical surfaces and gravity will make it run and sag. You must leave it reasonably horizontal for about 12 hours. Both Flex Seal and Plasti Dip are pretty noxious going on but apparently food safe once dry.

Test subject #2: “Line X”

Same box as test subject #1, but we took it to a local Line-X dealer to have them spray it. It ran $40, but I suspect a good chunk of that is labor that would effectively be the same with a larger item. The spray builds up a lot more unpredictably than the flex-seal and I had to cut some of it off to get the lid to fit in. I added a strip of foam weather seal (not shown) to both test subjects.


For testing in part 3, we’ll be using an old MIE cooler for baseline performance

Two tests were performed on each subject, to determine performance and durability.

For performance, each test cooler was filled with ice and set out in the shade, and timed as to how long it took the ice to melt. For durability, a full beer bottle will be dropped from 3′, cap-side down, to determine how well the lining holds up to abuse.

Read on…

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DIY Cooler (Part 1) Introduction

Or: An adventure to find a ice chest what doesn’t look like modern industrial excrement

There’s a certain exciting feeling when you walk into a period camp. Wow, look at this, and look at that! What’s going on over here? It’s like a period movie without all the boils and 90% less dysentery. Know what ruins that feeling? Looking at people cooking over an open fire with a pile of modern brightly colored plastic coolers tossed behind them in a forgotten corner. Is your period camp being ruined by a monster in the corner?


I know, there are lots of ways around this: Going full-period and getting rid of even century-old ice-based food preservation (tell that to the food budget and the horde of starving, picky kids). Painting over the bright colors (so now they look like painted MIE coolers). Putting the MIE inside a tent (where they take up precious dry space and are now super inconvenient to get at).

One of the more typical examples I’ve seen is where people take a modern cooler and build a wooden box around it. Even the best executed examples still look like a plastic cooler inside a wooden box. And if you’re already going to the trouble to make a wooden box, is there a way to kick it up a notch?

Its really not that big a deal to make a wooden box and line it with insulation. But that exposed insulation is 1) not durable and would get chewed up right quick and 2) not watertight, all that melting ice is going to make a big mess of your wooden box. Hand-vacuum forming a deep plastic liner seems like a royal pain and outside the capabilities of most home workshops. Forming a metal liner is even more of a pain and expensive to boot.

But, there is a potential solution! In recent years there has been a great expansion of options for paint-on/spray-on waterproof coatings. Spray-on bedliners, rubberized coatings in a can, all relatively inexpensive and easy to get. But, will it work?

Read on…

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Temperature Controlled Beer Box

I have “wisely” decided to bend my 20 years of on-and-off winemaking experience towards brewing beer; on one hand, starting simple by using extract-only recipes, but also skipping the whole bottle conditioning mess and going straight to forced carbonation. This seems simpler to me, having dealt for decades for sediment in wine bottles and wishing to not do any of that with beer. Also, experiences with others’ home-brewed beer have somewhat discouraged me from trying beer…If I want a beer, I just want a beer…Not a beer with special pouring instructions. Hence: forced carbonation.

As I’ve learned, forced carbonation works best if the beer and CO2 are kept cold. Now, having a family and right after hunting season, there’s not nearly enough room or family tolerance for emptying the fridge in order to stuff a keg in there. I could always just put it outside, but that’s not exactly a recipe for consistent temperature, and only really practical for 3-4 months out of the year. A separate device specifically for this seems like the best solution to this plan that doesn’t involve emptying the kitchen fridge. Now if we’re going through the bother of making a device that can cool a keg-sized object, if we add a little more technology so it can controls both heating and cooling, then we can use this device anywhere, any time of year, and not only for carbonating but also controlling fermentation temps, and even chilling kegs for serving. Yeah? Follow where I’m going?

Something like this has got to cost a fortune, right? Well, a few hundred, if you go out and buy some commercial unit. I don’t even know if I’m going to like making beer, so let’s keep it under $100.


Used small chest freezer from Craigslist: $40

Dual-acting temperature controller: $35

Heat lamp:$12

Lamp socket, lamp cord and other random bits from the shed

The rest is easy. Drill holes in the lid to accommodate the cord and mounting screws for the light socket and wire it up. The inside lid of this freezer was only thin plastic and wouldn’t hold the socket on its own with screws , so I used 3″ #10 bolts all the way through the lid. If the outside of your freezer is sheet metal, make sure to deburr the edges, especially where the heater cord comes through, you wouldn’t want those sharp edges cutting into the cord and shorting it out.

Tighten down the socket, add the IR heat lamp, find a convenient place to put the temperature probe. Legend has it that the best place for the sensor is right in the middle. I figure this is good enough, as long as you’re not expecting temperature control down to the individual degree.

And look! It fits a 5 gallon corny keg perfectly. Actually, it looks like it might fit three kegs and a CO2 cylinder!

Close the lid, plug the freezer and lamp cord into the temperature controller. Add some double stick tape and cable management to tidy things up and Bob’s your uncle.

There you have it: for less than $90, a temperature controlled box, good for fermenting your creation of choice, carbonating your drinky-drink, curing your homemade sausages, warming a metric ton of hotdog buns, the possibilities are endless!

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