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
Line-X
- 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
Conclusions
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.