LewBK wrote:Although Hoffmann struggled on this one, one conclusion I drew from his video is that a heat diffusion plate really helps with moka pots. Has anyone here tried this? Does it lead to better tasting coffee?

I've used one. No, it didn't improve the coffee. It slowed down the initial heating and delayed the effect of any stove setting change.

I used one to protect the plastic handle from the large gas burner I was using. Ultimately I switched to a small, portable gas backpacking burner. That gave me instantaneous control with a good low simmer setting. The stove setting wasn't especially repeatable however. Probably the ideal is an induction setup since you could have instantaneous control of the power as well as repeatability.

He begins discussing the "heating plate" at 15:54 in the video. Is the method he used the one you tried and it didn't work?

LewBK wrote:Although Hoffmann struggled on this one, one conclusion I drew from his video is that a heat diffusion plate really helps with moka pots. Has anyone here tried this? Does it lead to better tasting coffee?

I'm shopping for an induction plate with holes in it right now (and sourced one that looks identical to the one JH uses for like $10). I've had a problem with the bellman and Moka pots on a gas stove that it never seems to fit well and tips easy because the spaces to hold things are meant for larger pots/pans, things with a larger surface area. JH uses the induction plate as a type of diffuser but also to make a wider surface area for the moka pot to sit on. It's a great idea and I'm picking one up just for that purpose too. I'm wondering if it will also help with the bellman as I often keep the flame on low while steaming to keep a heat source going but it gets tricky as the heat because you have to hold it a certain way so you don't burn yourself. the induction plate may help with both, keeping a low heat source without a direct flame.

Another trick that most probably are not willing to do is use sand which has been used for hundreds of years. Sand is an insulator so the top of the sand may be cool enough you can touch it and the bottom much hotter. place the Moka pot at the bottom until you get the heat you want, then raise it in the sand to control that heat to cooler levers, lower and raise as needed. it works well for turkish coffee.

LewBK wrote:He begins discussing the "heating plate" at 15:54 in the video. Is the method he used the one you tried and it didn't work?

I didn't use the plate as a substitute for a stove that couldn't be adequately controlled. I used it as a shield to prevent heating the handle and sides of the pot. As Hoffmann himself said in the video, a stove with proper control could be used instead of a plate.

The thing about the plate is you can't really control it, other than maybe buying a different one. It's going to have fixed thermal characteristics that may or may not work for your particular situation. It just made things harder for me.

Give a diffusion plate a shot, maybe it will work for you. They're inexpensive.

It seems like the plate he's using is the 9barista one which is made of steel and aluminum. Interestingly, 9barista is also selling a new heating plate that is pure aluminum. I wonder which metal has the best heat properties to do what Hoffman is doing, gradually cooling the pot down. In the states I see ones from Bialetti that I believe is aluminum or steel, another that is all copper and one that is cast iron from Ilsa. Buying the 9barista regular one would be $29 to ship to the USA the newer all aluminum model about $40.

9barista has two models, one listed in the spareparts as heat exchanger plate for £7.95 and then another one call a heat transfer plate for £15.00. The one you see JH using in his 2nd video seems to be the first 9barista, I'm guessing aliexpress has them unbranded for a lot cheaper. in his latest video I think he went full out bialetti and just uses the one they have. The take away for me is probably any induction plate will do.

LewBK wrote:I wonder which metal has the best heat properties to do what Hoffman is doing, gradually cooling the pot down. In the states I see ones from Bialetti that I believe is aluminum or steel, another that is all copper and one that is cast iron from Ilsa.

I think the heat conductivity is the key factor, with copper being fastest to transfer (give up its) heat, then aluminum, and steel being the slowest. Mass of the plate would also matter. I think you'd have to experiment since your pot and overall brewing strategy might differ from Hoffmann's.

Sure you don't want to look for a stove you could just set to a low setting?

the transfer of the heat is related to the conductive properties of the pot and how hot the plate itself is. with a plate that heats up very quickly like copper it will also lose its heat very quickly so although still dependant upon the conductive properties of the pot itself, will more efficiently transfer the heat from the primary source to the pot but be less useful for hoffmann's purpose as a secondary heat source after the primary has been turned off. SS will take longer to heat up but will keep that heat longer so I would think would be more useful for Hoffmanns' proposed use. It looks like Hoffmann is using the Bialetti plate in his last video which is SS and the 9barista one he's using in the second video is SS with an aluminum layer in the middle. One thing Hoffmann notes is the larger the pot the longer you want your heat source so I'm sure plates with different conductive properties will work better with different sizes of pots, the bigger pots you want to hold heat longer and the smaller pots you want to release the heat quicker

In this case, heating speed of the plate of course depends a lot on conductivity of the metal, with copper having much higher conductivity than steel

Cooling speed, on the other side, doesn't depend as much on the conductivity of the metal. It depends mostly, besides thermal mass, on the conductivity between metal surface and surrounding air (which doesn't depend on metal), which is considerably lower than conductivity of the metal, even if it is steel

At least in theory. I didn't try measuring it ...

I plan on giving the Bialetti diffusion plate a shot.