# Oil slick in my espresso



## evoman (May 13, 2014)

Not sure if this thread belongs here or in some other section (technical?) -

I have never had this happen before, but the espresso shots I pulled this morning have heavy oil beads on them. I roasted the coffee myself, and I tend to do a dark roast (into second crack), and this batch was perhaps slightly darker than my usual, so there is a bit of surface oil (I was combating roasting in the cold weather by doing a larger batch of beans and it roasted much faster than usual, so rolled into second crack faster than expected).

So the easy answer is that the surface oil from the beans ended up in the shot, but I have had oily beans before and never had an oily shot. The dark roast ground finer than the last beans I ran through the grinder (these shots were pulled before I bothered to adjust the grind), which also slowed down the shot (it was a pretty slow). So all of these factors presumably conspired to pull out a lot of oil. But I have never seen anything quite like this (huge beads of oil - pretty shocking). Anyone seen anything like this (photo from the latte I made - I should have dumped the shots since it is an awful latte!)


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## DavecUK (Aug 6, 2013)

What espresso machine have you got?


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## evoman (May 13, 2014)

DavecUK said:


> What espresso machine have you got?


Londinium L1 (lever machine) - using my Sage grinder (my HG One is in pieces at the moment!)


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## DavecUK (Aug 6, 2013)

To be honest it looks like lubricant from the lever machine?


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## dsc (Jun 7, 2013)

I wouldn't expect silicone based grease to break down like this, although I've been wrong before









Try a different coffee first and see if it goes away. How does espresso look like before adding milk? What sort of milk do you use? Heavy "real" milk sometimes has a tendency to separate into fat patches like shown above (if you have milk / cream separation).

T.


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## evoman (May 13, 2014)

The oil was in the shot, so not from the milk (and I always use the same milk from the same supplier, including having used half that bottle already - it is homogenised). I didn't realize how bad it was or I would have pitched it before dumping it into the milk. The slow shot presumably left the pressurised water in the chamber longer than you would want, but I didn't think it would end up pulling out lubricant. I just assumed it was an extraction issue - too much oil pulled from the beans as a result of the bad conditions (that is actually from two shots - I started the grinder for the second before even pulling the lever on the first - I didn't realise that batch of beans would behave so differently since I tend to get very consistent behaviour from my roasts, even when I use different beans to start with)


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## jimbojohn55 (Jan 15, 2016)

I got something similar from my Gaggia when I first put a VST basket in it - no crema and lots of oil - finer grind sorted it out in the end


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## coffeechap (Apr 5, 2012)

When did you last service the group?


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## DavecUK (Aug 6, 2013)

dsc said:


> I wouldn't expect silicone based grease to break down like this, although I've been wrong before
> 
> 
> 
> ...


I have heard of people using vegetable oil and olive oil to lubricate levers, so nothing surprises me any more....I agree PTFE or silicone based lube wouldn't normally have yellowy looking droplets like that. Daves question re time between group servicing may be a possibility, although again I have not really seen that from even a really dirty lever group...but then really dirty is a matter of perspective. Perhaps the original poster can comment?

I just realised it's a photo of a latte, not an espresso under funny light....so it could well be oil spots from jersey milk or similar as you said.


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## Dylan (Dec 5, 2011)

I once used butter to lube my Mazzer bur carrier threads.

Did the job


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## Guest (Sep 28, 2021)

Although I'm not an expert in coffee, I do know a good little bit about how plants work (also not a biologist or botanist). I just pulled a very thick shot on my old cheap machine that I've had for a few weeks and had a similar experience. I think that what the oil could be is the natural oils that come from the coffee, something akin to olive oil or peanut oil. Depending on how finely ground your coffee was, you may have been able to pull out some of those natural oils. Again, just a college student that just thinks that this could be a reasonable explanation.


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