We made measurements without the weight valve also. All moka pots have different dimensions, ratios, ideal coffee/water amounts. For me temperatures at about 150 Celsius are completely out of range.

155 °C is obviously out of range (for drinkable coffee at least). I measured the opening pressure of the security valve with a pump, not by heating it

What I meant - measurement with brikka without a valve and cold water is not valid for ordinary moka pot, because ratio of air and water was different and extraction started and ended at lower temperature than in ordinary moka pot. In ordinary moka pot, it starts (1 cup , my measurements) around 60 and ends a few degrees below 100 - which is what designers planned I suppose

I've misunderstood one of your comments. Sorry.
Have you seen this study?

http://www.msc.univ-paris-diderot.fr/~p ... ticle2.pdf

Yes. That article and your video have been frequently mentioned in discussions about moka pot here. It helped me to renew things I learned in the school and university about physical processes. Quite interesting device from physical standpoint. They got even higher ending temperature than me - obviously finer grinding was used, so temperature went to about 120°C and pressure to about 1 bar. I was also experimenting with different grinds, but I went up only to about 0.5 bar or about 110 end temperature ... depending on the water quantity and coffee (finer/coarser/not tamped/slightly tamped) you just shift the whole process up or down in the temperature range. Tried also simulating brikka plugging the pipe with a cap and using less water etc ...

But eventually I gave up - no matter what I did, coffee was never just up to my taste and even with exactly the same parameters, measured temperatures were slightly different each time (probably also depending on the quantity of gas dissolved in water, slightly different strength of flame ...). I'm only using it with a pump now to make an espresso on a vacation as I mentioned, however at least about 5 bar is needed to get a real crema ... 1 cup pot holds 10-11 g of tamped coffee in the basket, just fine for me, somewhere between single and double shot according to standard italian coffee quantities

Hello:
Just saw this thread, so I might be late but...

I am an Italian transplant in US and I grew up with a moka pot. The first photo I saw in this thread showed coffee that appeared too fine and a bit too much. Second, the description of how much water was put in did not quite jive with my "how to".

Now, I don't have made any studies on the process, so take it with a grain of salt, but we put the water just ABOVE the safety valve and, when the coffee basket goes into the bottom part, there should be a drop of two of water bubbling up and covering the bottom of the coffee basket.

The rubber gasket must be clean of coffee, as should the threads. If those are not clean, no amount of "twist" will make the gasket seal. What usually happens, when the coffee basket is too full, that coffee gets into the threads.

When the pot is heating up, we kept the lid open. To prevent spraying of coffee, we put a spoon upside down over the central column, and balanced on the rim. As the coffee starts to bubble out and if is leaking around the middle, chances are that the threads were dirty. To fix the problem, get a thick, DRY, kitchen towel and use to twist the two half together while hot.

Careful, as you may burn yourself!! I take no responsibility for this ! You'll be surprised how much more you can tigthen the two halves.

Once this maneuver is accomplished, put the pot back on the stove on low heat. Turn off the heat when the flow of coffee becomes too bubbly.

Marco

naked-portfilter wrote:About temperatures...
We made this short film more than 2 years ago:

Great vid. Outside of the manufacturer I never thought someone would go through the exercise of doing an in depth analysis. Glad you did since we never see the manufacturers videos or published results. Your usage points for at end of video for a perfect cup are spot on.

I never tamp with a tamper with moka pots. I do tap the basket stem a few times on the stem downward to settle the grounds and level off if need be afterwards being sure not to be above basket lip. Fill water to just below valve and play with the grind to achieve optimal extraction. I found the grind determines flow. To fine and the water boils and the safety goes off before extraction. Too large and the becomes under extracted. Get it right and it just flows with optimal results in the cup.

Here is my collection below.