Heat Retention, Clever vs Bonavita Immersion - Page 2

Coffee preparation techniques besides espresso like pourover.
false1001

Postby false1001 » Jan 06, 2019, 3:41 pm

Materials isn't my strong suit, so someone correct me if I'm wrong, but I believe it's impossible for a porcelain or ceramic brewer to retain heat better than a plastic brewer. Ceramics will always have a higher thermal conductivity than plastic and will thus always be conducting heat away from your slurry to the surrounding air. This is a very general rule, as certain ceramics could have a higher air content or could just be engineered better, but fundamentally the materials will have different properties.

That said, an obsession with heat retention isn't necessarily going to result in a better cup. If you prefer more body or maltier notes in your coffee a porcelain brewer will help with that since your slurry will spend longer at slightly lower temperatures. If you prefer brightness, acidity, and sweetness then you're probably going to want to go with plastic. But a ceramic brewer with a lid, or with the proper brewing technique, can easily produce a much brighter, sweeter cup than say, a Clever dripper with a single pour and no lid. Also remember that at a consumer level your grinder is going to have by far the greatest effect on the result in your cup regardless of the brewer. Upgrading my grinder made my Chemex cups dramatically sweeter, despite its horrific heat retention properties.

Edit: Just to caveat, temperature obviously has a huge role in brewing coffee, but to be clear heat retention is not the end all be all. The following is purely conjecture, but I think Scott Rao's recent experiments with the DE1 helps prove somewhat the theory that pour over extraction is largely the result of the initial moments of ground immersion. Focusing on the temperature of the water coming out of your kettle will offer orders of magnitude more returns on the end product of your cup than focusing on the temperature of your slurry.

mikemaddux

Postby mikemaddux » Jan 06, 2019, 5:11 pm

false1001 wrote:Materials isn't my strong suit...


Coffee sure is complicated!

mikemaddux

Postby mikemaddux » Jan 06, 2019, 5:57 pm

My reason for performing this little comparison wasn't so much an attempt to decide which of the two brewers was better for making coffee, exactly. It was more a reaction to my surprise that Scott Rao recommended the plastic V60 over the ceramic one, because the plastic one had better heat retention. My experiment tended to agree with Rao - the outside of the Bonavita felt a lot hotter than the Clever, and a thermometer agreed. It was more of a Mr Science thing than a coffee thing.

EddyQ

Postby EddyQ » Jan 06, 2019, 10:30 pm

false1001 wrote:Materials isn't my strong suit, so someone correct me if I'm wrong, but I believe it's impossible for a porcelain or ceramic brewer to retain heat better than a plastic brewer.


I just looked up thermal conductivity of porcelain and polycarbonate (assuming that is the plastic used). The porcelain is 8 times more conductive than polycarbonate. But in order for heat to leave, it must conduct through air and air is 100 times less conductive than plastic. So the combined heat loss for air/plastic is less, but not a lot less. I suppose it is possible to be brewing with air blowing by, which would rob heat much quicker and perhaps the plastic would win.

As for heat holding, porcelain has almost twice the heat holding of polycarbonate of the same volume. SO if the porcelain is warmed to the brew temp, it will hold it better than plastic.

mikemaddux

Postby mikemaddux » Jan 07, 2019, 1:49 am

redbone wrote:Beyond heat retention it's all about what it tastes like in the cup. I can say they taste the same after many evaluations. Considering similar taste and similar process of using both I find I prefer the Bonavita at home for its non staining surface and ease of cleaning. The CCD has a place at work as I find it more portable and less susceptible to breakage. Can't go wrong with either based on taste. The choice is more of a preference vs performance.

In spite of my very simple test showing a small difference in heat retention I have to agree, I've noticed very little difference in taste. Today, though, I tried doing the brewing in an insulated container with a top and then, after four minutes, poured it through the Clever into the cup. That tasted very good, cleaner, to me, different, but not necessarily better.

vit

Postby vit » Jan 07, 2019, 4:03 am

EddyQ wrote:I just looked up thermal conductivity of porcelain and polycarbonate (assuming that is the plastic used). The porcelain is 8 times more conductive than polycarbonate. But in order for heat to leave, it must conduct through air and air is 100 times less conductive than plastic. So the combined heat loss for air/plastic is less, but not a lot less. I suppose it is possible to be brewing with air blowing by, which would rob heat much quicker and perhaps the plastic would win.


It's a bit more complex. Air conductivity in not that relevant, as it can circulate and transfer heat through convection and not only conduction. Because of that, heat flow between the surface and fluid (air, water) is calculated different way than heat flow through solid material (where the thickness is taken into account), but as you said, it will make the difference between plastics and porcelain smaller - once the outer surface of the brewer starts warming up, which also isn't instantly

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yakster

Postby yakster » Jan 07, 2019, 11:32 am

It would be interesting to insulate a BVID with a Sugru wrap around the outside to see if that makes a difference.
-Chris

LMWDP # 272

false1001

Postby false1001 » Jan 09, 2019, 7:08 pm

mikemaddux wrote:Coffee sure is complicated!


Coffee, like all things, is just applied thermodynamics :wink:

false1001

Postby false1001 » Jan 09, 2019, 7:26 pm

EddyQ wrote:I just looked up thermal conductivity of porcelain and polycarbonate (assuming that is the plastic used). The porcelain is 8 times more conductive than polycarbonate. But in order for heat to leave, it must conduct through air and air is 100 times less conductive than plastic. So the combined heat loss for air/plastic is less, but not a lot less. I suppose it is possible to be brewing with air blowing by, which would rob heat much quicker and perhaps the plastic would win.

As for heat holding, porcelain has almost twice the heat holding of polycarbonate of the same volume. SO if the porcelain is warmed to the brew temp, it will hold it better than plastic.


Exceptions prove the rule. Like I said, I was simply giving general properties of materials. Different brewers will be engineered and produced differently and I'm sure there are ceramic brewers that go to extra lengths to retain heat, but if your goal is to ensure higher temperature retention it will be hard to go wrong with a plastic brewer all else being equal.