2.9 oz thermal mug and cup

I don’t think the air space helps–it hurts.  As a building contractor I can tell you the goal of any insulation is to isolate small areas of air to prevent differences in temperature from creating moving air and therefore transferring heat.  If an airspace worked we would simply seal up the spaces between studs and not need to install insulation.  Foam does this better than fiberglass.  You want solid material that has a low heat transmission with lots of voids.

how about the mesh sleeves that are used around wine bottles (shipping)?  I purchased some rum at the airport (Duty Free) and they had these nice , thick foam sleeves.

The sleeves that Jon posted are almost exactly what I was envisioning.

Bob E’s comments however now have me questioning whether it will work.  I guess we just have to try it and find out :)

Reflectix® Duct Insulation Big Bubble Duct Insulation R‑6.0 would be the best choice material…………R-6.0

@zelph2: That got me very interested and I checked out their website. They also make big bubble outdoor duct insulation R-8.0. But they’re both nominal 1″ thick.

Their non-big bubble duct insulation R-6.0 is 5/16″ though, which is perfect.

David, go back and read what they say about the R8 big bubble.

The product provides an R-8.0 when installed with a 0.75” air gap between the duct and the insulation, and R-6.0 when installed direct to the duct without a spacer.

Got it. Same stuff, different installation, not useful as mug insulation.

@bobellenberg

Very nice,  are you worried about leaching from the plastic?

@bobellenberg

Very nice,  are you worried about leaching from the plastic?

Also curious why 4 pieces instead of 1 like you do for refletix?

Tested a double layer of Reflectix:

30 min: 81 C/178 F

60 min: 72 C/162 F

90 min: 65 C/149 F

Only slightly better than a single layer:

30 min: 80/176

60 min: 70/158

90 min: 61/142

I’m surprised. Again. Double thickness produced only 1-7% improvement.