The infrared emissivity of bare clean metals is very low. It is very high for most polymers. If one point an infrared thermeter at a bare heated espresso boiler or group it will read only a few degrees above ambient temperature as a result of this. However, polymer coated metal surfaces will read close to the correct temperature. This makes infrared thermometers very useful for measuring temperatues of objects with polymer coated brass surfaces and close to worthless with bare metal ones.

There is another consequence of this fact! My 1999 La Pavoni Europiccola is a REAL brass and copper one. La Pavoni has also made many FAKE ones! (Real ones are commonly sold for a noticibly higher price because the bases do not corrode. Fake ones should be sold for less than chrome ones. If purchasing one of these machines make SURE you are not getting the fake!!!!!) The boiler of this machine is BARE, not polymer coated, copper. When freshly polished and at about 116 degrees C an infrared thermometer will give a temperature of only about 35 degrees!!! If one put one's hand perhaps 3 cm from the boiler one can hardly detect infrared warmth. The group is polymer coated brass. If one put one's hand near the group one can feel substantial warmth from infrared radiation, and the IR thermometer reads about 112 or so degrees for the top of it.

A serious consequence of this is that polymer coated groups lose much more heat by radiation than bare metal ones. This matters a LOT. Real brass and copper La Pavoni machines obviously have less tendency to overheat than chrome plated ones with their bare metal surface.

The Elektra Micro Casa a Leva also comes in chrome plated and polymer coated versions. The same thing must be true for it. Mine is polymer coated. It never seems to have over heating problems.

What does the contact temps say? using a contact probe
Just because you have a bigger heat loss with one type ,you could (not saying that you do) end up with the same temp
the heating element just have to work more often

But all this brings up some toughs i had made about coating the copper tubes and boiler on a lever machine
I would look , good with a glass casing and shiny boiler and tubes .

I just did an interesting test with my 1999 second generation real copper and brass La Pavoni equipped with pressurestat. I removed the normal boiler cap and installed my special thermometer well cap for this test. Room temperature was 21C. The table below shows the results:




"Turn off" column refers to temperatures when the pressurestat turned off the heating. "Bleed" column refers to temperatures after bleeding when the pressurestat had turned off again. "5min" is 5 minutes after the pressurestat turned off, and 15min is 15 minutes after the pressurestat turned off after bleed.

The boiler of this machine is NOT coated with protective polymer. It was polished and cleaned only six days ago. There is not much oxide coat on it yet, note how its IR temperature is hardly above room temperature at any of the times temperature was read even though the well temperature is 116 or so.

The group has a completely intact protective polymer coating that has very high emissivity. The neck of the group is in direct contact with steam. Note how the IR temperature of this area is almost the same as the observed digital thermometer reading from the thermometer well immediately after the machine was thoroughly bled. (I took great care to bleed the machine very thoroughly for this test, so that no detectable air bubbles were visible using the "olive jar" test when I moved the group handle upward a bit.)

I did not record data from the portafilter, because it has no polymer coating. In my experience hot coffee is corrosive enough to the usual polymer coatings used on brass and copper surfaces that the coatings on portafilters fail within a year or so. I stripped my brass portafilters long ago.

Just before the 5 minute data set I made a shot of an extraordinary Kenya coffee. It was excellent. (I should have made one after the last test, but I had already had enough espresso for one sitting, because I had drunk 2 cups about an hour earlier.)

This shows just how good IR thermometers can be for determining temperatures at points on espresso machines, and there are not wires running everywhere! However, the group must have a polymer coating.

I have read the temperature of the boiler and group on my chrome plated 1964 first generation La Pavoni, even when it is up to temperature the IR emission is poor, so the temperature it gives is about 40C.

Note, by the way, that the temperature of the top of the group changes little from initial bleed on to 15 minutes, but the taper point and below slowly rise.

Plating and a highly polished surface reduces the emissivity. Coating with any clear coat finish will increase the emissivity. I plan on stripping all clear coat and polishing the brass and coper to a high polish and then cleaning thoroughly and allowing the natural aging process to proceed to completion. The naturally oxidized copper and brass will have a relatively high emissivity without the plastic coating and be stable.

Different materials have different ir imesy

On some meters you can calibrate/adjust the meter to the material

Did you test the values with at contact meter ?
if the meter is set to a lower emission then the coating has , then the readings will show higher than the actual temp

i use a cheap K type contact probe to check that , once done , its so much easier just to use the Ir meter
http://www.ebay.com/itm/K-Type-surface- ... 1085323853