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  • Extra weight added when steaming?

    Hello all, I have noticed that when steaming with my Rancilio LUCY that the weight of the milk increases by about 25%. If I steam 100g of milk up to 68C and weigh it again its about 125g. Im letting the steam build up for about 2min after pulling the shot. Is this long enough? Is my steam too "wet"? Or is this normal? The same happens for other volumes as well. The texture of the milk seems OK, no big bubbles.

    Andrew.  

  • #2
    Re: Extra weight added when steaming?

    Do you purge the steam wand before steaming?

    charlie

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    • #3
      Re: Extra weight added when steaming?

      Yes, its normal - you are adding air to the milk; air has weight (weigh a balloon before and after inflation).

      25% increase in weight sounds like a lot. You would be adding a small amount of water, I imagine, as steam condenses in the initially cold milk.

      You could try steaming plain water without adding air and see how much the weight increases (ie just keep the steam tip completely submerged). That could give you an idea of any water being added.

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      • #4
        Re: Extra weight added when steaming?

        Originally posted by 68627760606F7B7D0E0 link=1242702533/2#2 date=1242703525
        25% increase in weight sounds like a lot.
        25g would be 25ml of weight if all water.
        Thats about 5 teaspoons isnt it?

        I think youre understating it flynn.
        Sounds more like a bloody lot to me.

        My machines off now but Im willing to sacrifice 100ml of milk tomorrow to see what happens.


        P.S. I dont think air weighs very much.
        How do I zero my scale in a vacuum so I can weigh the air in my balloon?

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        • #5
          Re: Extra weight added when steaming?

          Flyn, the balloon weights more after blowing up due to an increase in pressure, Im not sure that the microfoam can hold air at pressure significant enough for it to increase the weight. For all intensive purposes I think that all the weight increase can be attributed to water from the steam.

          As TG suggests I will have a go tomorrow and see what results I get.

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          • #6
            Re: Extra weight added when steaming?

            Originally posted by 516D706B616077626A61050 link=1242702533/3#3 date=1242717318
            P.S. I dont think air weighs very much.
            How do I zero my scale in a vacuum so I can weigh the air in my balloon?
            No it doesnt weigh much - certainly not 25g. But I do remember the science experiment I did at school where we use a beam balance scale to weigh the balloon before inflation. When you inflated it, the scale tipped towards the balloon side proving it was heavier. Conclusion: air has weight.

            You dont need a vacuum to conduct the experiment.

            I suspect Charlie could be on to the main reason for the weight increase

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            • #7
              Re: Extra weight added when steaming?

              In all practicality, air has no weight. If it did, we would be weighing the column of air above any object we were weighing as well as the object.

              Indeed, air is actually just lots of different molecules floating around and technically these will have weight. Thus, if we squeezed an amount of air into a smaller space, we will increase the density of air (or pressure of air) within that space...making it heavier than air that has not been compressed into a smaller space. At least thats what my brain tries to pass off as logic.

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              • #8
                Re: Extra weight added when steaming?

                Thats a lot more than I would estimate. Once I get some scales Ill check (or maybe someone else could do it). Remember (admittedly at sea level and 20ºC) air has a density of 1.2kg/m^3.

                My suspicion is youre getting a lot of water – are you bleeding the wand dry before you steam? I turn it on until no water comes out, just steam, and the boiler light is on.

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                • #9
                  Re: Extra weight added when steaming?

                  Originally posted by 46776079787F74796F160 link=1242702533/6#6 date=1242725317
                  If it did, we would be weighing the column of air above any object we were weighing as well as the object.
                  You do its just when you zero your scales you are adjusting for it. If I recall my highschool chemistry 1 atmosphere is equivalent to a column of water 10m high.

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                  • #10
                    Re: Extra weight added when steaming?

                    Originally posted by 5A7665637E767B485A78797C726E170 link=1242702533/8#8 date=1242726196
                    If I recall my highschool chemistry 1 atmosphere is equivalent to a column of water 10m high
                    How wide? Makes a bit of a difference to the calculation ;D

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                    • #11
                      Re: Extra weight added when steaming?

                      according to wolfram dry air is
                      28.96g per mole what ever that is

                      Comment


                      • #12
                        Re: Extra weight added when steaming?

                        I can guarantee that there would probably not be enough air in your textured milk to account for 1g let alone 25g

                        There are 44 Moles of air in 1m3.
                        1m3 weighs 1.28kg

                        so 1 mole= 29grams

                        (thx to Wolfram)

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                        • #13
                          Re: Extra weight added when steaming?

                          This is getting quite OT but: -
                          a mole is 6.12 times (10 to the power of 26) atoms. the width is the surface area of the item in question (could be 1mm or 100m - in other words the greater the surface of the object the more air is sitting on top of it).

                          And no the quantity of air in the microfoam would not even register on a set of scales yet alone account for an increase of 25% (this would have to be water).

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                          • #14
                            Re: Extra weight added when steaming?

                            To derail to almost unheard of levels, Im not sure about your mol figure (but whats three orders of magnitude between chums?).

                            Hes still right though, I didnt want to be so explicit though. But, I am still just a mathematician, so I dont want to be so exact. Its almost surely ( for those who understand) not air causing your weight increase.

                            Another thought: When you weigh your milk, do you have the thermometer in? Maybe that would do it, too.

                            Comment


                            • #15
                              Re: Extra weight added when steaming?

                              Originally posted by 1D3223153B36343C14363132570 link=1242702533/1#1 date=1242703470
                              Do you purge the steam wand before steaming?

                              Yes, I purge the wand several times before steaming. Initially a few spurts of water then only dry steam comes out right at the tip.

                              Andrew.

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