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Sunbeam EM6910 Screaming / Too Much Air In Milk

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  • #31
    Thanks for the response MrJack; it is appreciated.

    I will say on the toluene issue, I read his caution, shuddered and decided, child or not, I ain't having any stuff like that anywhere I might contact it.

    I have tried his idea about removing the wand before the steam has finished - I was doing it anyway after my barista course but I tried removing it earlier. The only way I could get a splash of milk was doing it almost as soon as I dialled down the steam and doing it slowly. If I followed the line as he mentioned AND did it smoothly and quickly, the most I got was a few larger bubbles in the surface.

    I didn't get from his posts that you are meant to remove the wand at full pressure - he says 'as soon as the sound of the steam pressure drops in pitch remove the wand along the line in the jug' and that the goal is to have the steam pressure drop to zero just after the nozzle leaves the milk. To me that is clearly a timing process designed to be a safe way to remove the wand without risking milk up the tip.

    Also, the milk entering the wand is not an either/or issue. The temp of the wand can easily be enough to dry almost boiling milk in the milliseconds after the steam ceases. With no steam pressure forcing the milk to stay outside the nozzle I have little difficulty in understanding the milk might enter the tip - whether it is 'sucked' in or not I haven't worked out as I don't know enough about how the pump works. i.e. if the pump is merely pushing water into the thermoblock, I don't know what effect stopping the pump has - does it maintain a partial pressure or does it create a semi-vacuum when it stops? The first would mean there is unlikely to be much of a 'suck' effect, the 2nd implies there would be.

    I am puzzled about the purge issue you mention for a small amount of milk - to me purge is what you do after the texturing but TampIt only mentions the flush of water at the start of the steaming process - is it that to which you refer?

    I take what TampIt says as at least indicative of what happens because of my experience with my steam - SOMETHING was blocking my steam system and it burst clear after I left the cleaning solution steaming through it for about 15 minutes. That 'something' left dirty brown water in the bottom of the container I was steaming into and had a smell like burned custard - if it wasn't milk burned to the inside of the wand I don't know what else it could be. The system has had only pure water through it for at least 9 months.

    The sound of the pump didn't change so to me that says the blockage was either IN the thermoblock or on the wand side of it. My logic might be incorrect but if it had been a blockage on the pump side of things I would expect the pump sound to have changed and it didn't.

    He also advocated a tamping method I have been trying. For me it has evened out the results I have been getting from my grinder. I was finding the same setting (& as best I could, same tamp pressure) would give me one coffee just above the green on my pressure dial (& a slower pour to get my 60ml) and the next would be in the lower section of the yellow. (& a faster pour to get 60ml - i.e. the pressure gauge is behaving correctly)

    By following TampIt's method I now get consistent results (and no leaks from the showerscreen at all) and my coffee is improved.

    So, from my PoV, from actual results, I have to agree with what he says. He might be slightly nutso to even consider toluene (but we don't know where he used it - perhaps in a well-ventilated shed?) and he didn't actually say bicarb would deal with it, just suggested lactic acid might be neutralised by it. I don't know if what is in the wand would be lactose or lactic acid so can't comment on that and with my steam working as strongly and quickly as it now does I have no need to try it.

    I think with the hydrofluoric acid comment he was pointing out the volatility of fluoride, not saying the acid is in tap water - but I am a dedicated opponent of fluoride in water at all so it was a comment I probably nodded along with and moved on. I think it was over in the My New Machine thread. Fluoride IS corrosive in almost any form - it causes many of the symptoms we are told it is being put in the water to cure and in many of its forms is a known carcinogen. Maybe it is my prejudice but I don't have many issues with thinking of fluoride as a causative agent in corrosion.

    So I will give you that and the toluene comment, but the rest seems OK as far as I can tell by trying it or by my experiences with the machine.

    Comment


    • #32
      Originally posted by MrJack View Post
      No worries. If you have the facilities, perhaps produce a short video and put it in a new thread? Probably easier for a "newbie to espresso machines" to digest.
      I did not do it that way because I have no idea how to post a video in CS, nor do I have easy access to video facilities other than a cheap home one (colour is terrible) and a full blown video production suite (seemed like overkill).

      I am new to CS, so I felt I would be cut a little slack on unwritten protocols, if that is what I have breached.

      I am beginning to think that it would be a better approach, and it is now on my "to do list". Do not hold your breath, it may take a few weeks as a starter.

      I also felt, perhaps incorrectly, that a set of instructions along the lines of "why it happens" and "how to do it correctly" would not be confused with a standard post like this.

      Cheers
      TampIt

      Comment


      • #33
        Despite the last few weeks largely spent at the hospital bed of a good friend who fell 4+ metres off a ladder whilst chainsawing a tree (at 86!), and my troll meter quivering quite a lot, I will reply to your “concerns” other than those already covered by Journeyman.

        Originally posted by MrJack View Post
        - suggesting people clean thier (sic) equipment with toluene and methylated spirits
        Firstly, I confess I am really scratching my head as to why you would prefer to use cleaners inside the machine, which generally leave some residual taste for your next coffee, compared to solvents outside the machine, which don't (unless you do not rinse them out thoroughly). If you are going to use solvents on the showerscreens anyway, adding the baskets and any other potentially tainted parts is a no brainer.

        I do not have (or would want) toluene at home. One of my many “past life professional clients” is a precision medical grade stainless steel instrument making company. They start at 316 and mainly use 4xx grades. After trying virtually everything else in their biologically vented lab, including an ultrasound bath we reached for their toluene. It only worked after a long soak, which leads to an interesting question “What is in this gunk?”.

        All the standard coffee cleaners which work reasonably well on any boiler machine I have encountered do not work as well on any of the 6910's I have seen. I have no firm idea why that is true, however it is easy to test. Get any three month old 6910, that just uses coffee cleaners in the water and has never had the showerscreens removed. Undo the central grouphead screw and take the two showerscreens off. Yes, there are two showerscreens on the 6910 which is very uncommon: probably part of the gunk issue.
        Originally posted by TampIt
        The upper / inner showercreen is particularly hard to clean as it has tapered holes which can trap an inordinate amount of what I call "coffee tar". When it gets hot, the tar moves around, often blocks holes at random and varies the pressure” (my post 135 to Journeyman).
        Two points: Firstly, I would not want to drink anything that passed through that, so AFAIAC it has to be removed somehow. Secondly, there may be a cleaner out there somewhere that removes it, however none of the ones I encountered indirectly via any other 6910 I have ever seen actually managed to remove the stuff on/in the showerscreens.

        To add to the 6910 owner's woes, the Sunbeam manual has a real “sin by omission” here. It does not tell you how to take the showerscreens off for cleaning. Unless you get the instructions for replacing a seal they probably do not exist anywhere else either.

        Result: A machine producing inconsistent coffee due to a crying need for a basic clean. Short of removing the single screw and directly attacking the showerscreens, I know of no easy way of doing it.

        Originally posted by MrJack View Post
        - how can a steam wand which has cooled enough to 'pull a vacuum', be hot enough to contact dry milk (which would require boiling).
        Refer to my post 15 to Yelta. This is 6910 specific, so ANY other machine may be different. I would also point out (again) that I keep on seeing 6910 wands from intelligent people that follow the manual religiously & are partially blocked / caked with milk internally. Rex ipso loquitor.
        Water turns to steam at 100 Celsius at normal pressure. 6910 Steam is 92 Celsius at 4 bar.
        Volume of steam is approx 365 that of water.
        Milk breaks down at 70 to 71 Celsius.
        Like a number of “new style” wands, the 6910 has a vent 20mm away from the (single) nozzle.
        To measure the actual temps, I used a 5 sensor “instant read” medical thermometer setup. This adds the following actual measurements (averaged for simplicities sake):-
        The wand exterior gets to 85 Celsius at the end of frothing a 400ml jug, and reaches 90 to 91 Celsius using the 500ml jug that comes with a 6910. Most people use a 500 to 600 ml jug.
        When you turn the steam off, the drop in pressure “immediately” (i.e. well under a second) condenses the steam back into water. It contracts to 1/365th its volume and is capable of exerting a strong partial vacuum.
        If the wand is used as shown in fig 40 of the manual, the nozzle & vent are both below the milk surface.
        About 5ml of milk is sucked up into the wand EVERY SINGLE TIME unless you remove the wand as I described.
        Due to the fairly high thermal mass of the wand (i.e. compared to other machine's wands), the exterior is still at 80+ Celsius 17 seconds later.
        The five ml of milk will break down, and any of the solids directly in contact with the wand adhere to the inside of the wand where they are baked on.
        When you flush the wand out, you help to bake at least some of the milk gunk still on the inside of the wand even more.

        Originally posted by MrJack View Post
        - the assurance that even full steam pressure will not result in splashed milk if you get the angle right.
        Using a 6910 at full (4 bar) pressure doesn't splash in any of my 400, 500, 600 or 1000ml jugs (several of some sizes) i.e. as originally stated. However it will trash your microfoam (90%+ certainty). I still cannot read that and see how that could be possibly be construed as a recommendation. It is very clearly “if you err on this you will not get hurt unless you also stuff the withdrawal line up”.
        Safety Warning: Never attempt this on any other machine or ANY 4 nozzle tip, you will probably get burnt. The 6910 steam delivery is limited to 4 bar, using a single nozzle tip. Different world.
        Originally posted by MrJack View Post
        - suggesting that purging the steam wand isnt required when you are only steaming a small amount of milk (no justification given - I personally prefer not yo fill my milk jug with water)
        Reread it again, carefully this time, I said to experiment. To expand a little, even amongst full cream milks the actual fat content varies substantially. Add to the mix certain dairy companies which remove a portion of the cream to maximise their profits and there are even more variables. I know, as does any NSW farm boy in the 50's & 60's, that Dairy Farmers used to do this to Jersey milk back then – the cream in the bottle dropped from over 50% to barely 20%, and that is after allowing for homogenisation. To be more specific using Fresian, Jersey or Guernsey milk which has not had most of the cream removed it is common to get better latte quality crema by adding a small amount of water. Additionally, when using a 400ml jug in a 6910, the steam tends to overheat the first part of the milk in a small jug which may scald it. Letting the steam pressure build up more slowly by letting a little cool water start the desired whirlpool, also removes that issue from the equation.


        Originally posted by MrJack View Post
        - the implication that lactose 'acid' (a sugar) build-up might be removed with bicarb (what about the proteins etc.?)

        I have stated that “Chemistry is not my strong point” in my original post #9 in this thread. I just went to wikipedia and retrieved this (as is, no formatting added by me):-


        Lactic acid - Wikipedia, the free encyclopedia: Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3. It has a hydroxyl group adjacent to the carboxyl group, making it an alpha hydroxy acid (AHA).


        Looks like it is an acid to me. The word sugar is rather absent. Preferably check your own facts before posting “iffy” & incorrect items. Take it up with CS chemistry gurus from this point on.


        IMH(very amateur)O, I already stated that any commonly used domestic base would be worth a shot on the high school chemistry concept that bases neutralise acids. OTOH, perhaps the ingrained milk gunk in a 6910 wand is no longer lactic acid anyway. Way beyond my skill level. As I never have to go through this procedure on my own gear, I admit to being fairly unconcerned.


        Any takers in CS to shed more light on this one?

        Any further queries on this should probably be on a private message. I am sure most newbies would be lost by now, which defeats my whole purpose in trying to assist them.

        TampIt

        Comment


        • #34
          - I would rather use (and recommend) a cleaning solution formulated for the cleaning job at hand, than to use a highy carcinogenic, reactive, volatile (and flammable) organic solvent ( and which is basically insoluble in water), with who knows what residual impurities; regardless of the fact it is a good solvent. I have actually used it for cleaning laboratory glassware in a fume hood, whilst wearing PPE; I wouldn't drink out of that glassware either.

          - rasing the pressure to 4 barg provides steam at > 100ºC. Reducing the pressure alone will not result in condensation of the steam. However removing heat, and the supply of additional steam, would probably result in both (at independent rates).

          - if a small amount of water is good for the microfoam, why only advocate it when preparing a small amount of milk?

          - lactose and lactic acid are not the same thing. In spite of your Wikipedia research, you seem to have missed the point(s).

          Comment


          • #35
            Originally posted by MrJack View Post
            - I would rather use (and recommend) a cleaning solution formulated for the cleaning job at hand, than to use a highy carcinogenic, reactive, volatile (and flammable) organic solvent ( and which is basically insoluble in water), with who knows what residual impurities; regardless of the fact it is a good solvent. I have actually used it for cleaning laboratory glassware in a fume hood, whilst wearing PPE; I wouldn't drink out of that glassware either.
            Which is your prerogative, but there's no reason to discount a useful solvent on emotional grounds and assuming a decent purity there will be nothing left behind, especially since we're talking about parts that reach over 100 degrees.

            If you're going to DIY chemicals it's up to you to know the potential impurities (which is an issue here, because Diggers, for instance, like to put all kinds or stuff in some of their solvents and acids)

            Piranha works great on cold-drip/syphon, I imagine :P

            Comment


            • #36
              Originally posted by MrJack View Post
              - rasing the pressure to 4 barg provides steam at > 100ºC. Reducing the pressure alone will not result in condensation of the steam. However removing heat, and the supply of additional steam, would probably result in both (at independent rates).
              Firstly, I would strongly suggest you proofread your posts. No idea what 4 barg is, most of your posts have at least one typo. Careless.
              Secondly, the SB 6910 steam wand temperature did not exceed 92 Celsius even when using my 1.5 litre jug (which is the extreme outer limit of 6910 milk frothing). Reducing the pressure down to one bar WILL immediately condense the steam out – it absolutely has to. Your are showing extreme ignorance by bandying about > 100ºC (i.e. greater than 100ºC for those who do not know that notation). The 6910 NEVER gets its steam wand to 100 during normal usage, and I really doubt that it is capable of doing so – even when Journeyman left his going for the duration of a phone call it probably did not reach 100. Once again, you are trying to use the example of boiler machines on a 6910, and they do not apply in the majority of circumstances, including this one. Careless.

              Originally posted by MrJack View Post
              - lactose and lactic acid are not the same thing. In spite of your Wikipedia research, you seem to have missed the point(s).
              I have stated that “Chemistry is not my strong point” several times. My bad for a spell checker that “corrected” my lactic acid typo to lactose acid which does not exist anyway (or does it? I actually do not care). If I had realised it earlier than now, I would have corrected it to lactic acid. Your bad for trying to make a mountain out of it in such an obscure way that no normal person reading your post would have worked it out.


              Originally posted by MrJack View Post
              - if a small amount of water is good for the microfoam, why only advocate it when preparing a small amount of milk?
              Read it again. I add water to full cream milks that need it all the time. Fast microfoam: just use that plastic tasting stuff called “cappuccino milk” (which may be just a WA affliction) and stand back in a hurry as it froths. Just don't expect farmboys like me who grew up with the real stuff to drink the end result if you do decide to use it.


              Originally posted by MrJack View Post
              - I would rather use (and recommend) a cleaning solution formulated for the cleaning job at hand, than to use a highy carcinogenic, reactive, volatile (and flammable) organic solvent ( and which is basically insoluble in water), with who knows what residual impurities; regardless of the fact it is a good solvent. I have actually used it for cleaning laboratory glassware in a fume hood, whilst wearing PPE; I wouldn't drink out of that glassware either.
              As I pointed out (too often) the toluene was a last resort. My normal solvent plus numerous others are all water soluble. Residual impurities from any decent solvent which is water soluble: NIL as you well know (or should). Then flushing any minute traces out of the system afterwards “reduces the zero”. If you smell or see anything in the flushing water, you need to be more careful next time (also a repeated statement by me). Your deliberate misinterpretation of what I stated is, once again, careless.


              I would now throw you an easy practical challenge:
              Explain using entirely different logic how so many 6910 owners block up their steam wands.
              Explain why using an internal cleaner in a 6910 is preferable to an external cleaner if one uses clean, filtered rainwater as a starting point.


              Time to put up or shut up.


              TampIt

              Comment


              • #37
                Hooley dooley.... Perhaps a mark high on the wall and a peeing competition to see who can wet it first?

                Way too busy to read thousand word plus posts. If not, I'll find something to make me busy.

                Comment


                • #38
                  Originally posted by TampIt View Post
                  Firstly, I would strongly suggest you proofread your posts. No idea what 4 barg is, most of your posts have at least one typo. Careless.
                  Bar (gauge pressure, as distinct from absolute). It's also not great to be pedantic about proofreading in one paragraph then claim typo in the next... just saying.

                  Comment


                  • #39
                    Dragunov is spot on. Since we are talking gauge pressure barg, aka bar(g), is the actual unit we are referring to. The use of bar (while common on this forum) is generally understood to be absolute pressure. The distinction is particularly important when talking about fluid properties.
                    The saturation temperature of steam at 4 barg is 151ºC. If your 6910 indicates it can produce steam at 92ºC and 4 barg then either it's a) magic, or b) incorrect.

                    Engineers use tools called steam tables to determine the properties of steam under various conditions. Steam (for obvious reasons) has been studied extensively and its properties well understood for over a century.

                    When you reduce the pressure applied to saturated steam, the saturation temperature falls, which means some of the liquid will flash to vapour (i.e. the opposite of condensing). Condensation will result if you remove heat, but this is a slower process.

                    I don't think I have stated that milk up the steam wand cannot happen, I just found the explanation misrepresented the facts.
                    Last edited by MrJack; 8 October 2013, 11:13 AM.

                    Comment


                    • #40
                      Am I the only one who turns the stream trap off and withdraws it just before the stream flow stops?

                      It's really not that hard unless it's hard on/off like a solenoid.

                      Comment


                      • #41
                        Originally posted by Dragunov21 View Post
                        Am I the only one who turns the stream trap off and withdraws it just before the stream flow stops?
                        Nope, I think most of us with any experience do exactly the same

                        As far as 700 word pedantic rants are concerned, I'm with Talk_Coffee, I simply don't have the time or inclination to wade through this sort of nonsense

                        Comment


                        • #42
                          I do it. I believe TampIt was advocating that also. I still purge regardless.

                          On my breville BES820 it was less consistent as it relied on the pump switching off, rather than being controlled by a valve.

                          Comment


                          • #43
                            I think anyone with common sense does. Those who don't are the same sort who never backflush their machines, and are bound to run into trouble anyway. I.e. not a concern for us 'snobs'.

                            Comment


                            • #44
                              Originally posted by MrJack View Post
                              I still purge regardless.
                              Course, I just think you'd have to actually try to manage to suck any back up (as distinct from a bit just being left on/in/around the tip).

                              Comment


                              • #45
                                Originally posted by Dragunov21 View Post
                                Piranha works great on cold-drip/syphon, I imagine :P
                                hah that sounds like fun

                                I made up piranha solution once for a colleague and only after read this account of an accident in a lab

                                On a serious note, if people want to use a *strong* solvent to clean with I would probably reccomend acetone or ethyl acetate which are of low toxicity. As far as I know you can get them as nail polish remover (purity?). Be careful with any solvent, as virtually all of them are extremely flammable. Much more so than ethanol!

                                If you want to avoid toluene you're going to have a hard time. Its in petrol... along with benzene which is 1000x worse!!!

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