Channelling!?

[Kiwi_Jonno]

Help!

The last week or so iv noticed my shots have been starting perfectly, perfect flowrate etc but blonding happens far to early into the shot. After say 15sec, even tho the extraction rate was bang on. The coffee to start with started to drip like honey then flow as it shud. After I extracted the shot, I carefully knocked the pluck out and noticed it was a lot darker (wetter) around the edges. Although it was clearly wet in the middle, and all the way thru the pluck, the edges were a lot darker as if channelling down the side had occured.

After about ten shots over a few days the shots were drinkable just. I norm pull 1-1.5 oz restrettos.

Iv read that tapping the side of the basket can cause this, but I dont. I fill filter, settle, and a solid tamp once and polish so not sure why channelling is happening down the side. Am using the sunbeam tamper, am wondering if cos it doesnt goto the edges completely its making the water run down there? After extraction there is often a slight (2mm?) hill or grinds up the side of the basket all around the egde. Theres always the screw mark from shower screan and firm not wet pluck. Sometimes the very middle bottom of the pluck is darker and wetter to but not always. Theres never any "dead" dry spots at all.

Anyone know wat I am doin wrong?

I recently changed the beans for fresher ones and the coffee is a lot better and nicer, it flows a bit better to but still has the darker wetter rim...

[lucinda]

Re: Channelling!?

What is yoiur machine and type of grinder?

You could try double tamping. I usre this and get great results.

Basically you half fill your basket, knock it and then lightly tamp. Fill the basket with the rest of your beans, knock and then give another firm tamp and polish.

You may need to up your dose a bit too as wet puckks are in general a sign of underdosing. I tend to weighmy beans out before putting them in the grinder so I get the correct amount of coffee.

I hope this helps

[segrave]

Re: Channelling!?

If your tamper dose not exactly fit your basket and you only tamp once then then you will always be leaveing some small amount of coffee (2mm?) around the edges untamp this is then the path of least resistance for the water so you will get channeling.

The answer is either tamp a few times to make sure its all even or get a tamper that fits your basket exactly i.e Pullman

[Saambo]

Re: Channelling!?

I noticed in another thread that you have an EM6910. Ive never had any chanelling issues (or I dont think I did), but the sunbeam tamper suppplied with the 6910 is way too small. It was always a PITA tamping with it because you had to do a lap around the rim of the basket to get the edges packed (way too much effort for me). Since I got my Pullman, the shots have been more consistent. I was amazed at how much difference a correct fitting tamper made. Having said that, It is only one of the possibilities for what you are seeing around the edges of your puck. Changing beans usually means changing the grind setting slightly for me. Although I buy my beans from the same place and havent needed to change the setting on my EM0480 more than 1 click up or down since.


Cheers

[Kiwi_Jonno]

Re: Channelling!?

If your tamper dose not exactly fit your basket and you only tamp once then then you will always be leaveing some small amount of coffee (2mm?) around the edges untamp this is then the path of least resistance for the water so you will get channeling.

The answer is either tamp a few times to make sure its all even or get a tamper that fits your basket exactly i.e Pullman

Hmm but then you read that tamping hard more then once creates channelling thru the pluck, as apposed to down the rim of the pluck. I use sunbeam em6910 machine and the matching grinder which works fine. Sounds like it prob is the tamper cos theres the slight 2mm gap round the rim where the coffee goes up the side of the basket during extraction.

Saambo, what do you mean with PITA tamping? And I can relate to having to do a lap around the edge to get the rest of the grinds tamped! I norm do that then POLISH after the hard tamp. So save tamping again. I spose that means they arent tamped at the edge like the rest of the pluck....?

[JavaB]

Re: Channelling!?

Kiwi_Jonno

There is only one answer - get a tamper which fits EXACTLY....

You need to tamp right up to the edge to seal the puck against the wall.... so if you dont have a tightly fitting tamper you need to do the north, south, east, west tamp..... 4 tamps at least- each one of which can disturb the rest of the puck - and cause channelling there....

A polish at the edge wont do anything for you - without compression it wont seal.....

So get a fitted tamper - one tamp right up to the edge - and a polish if you wish...... and the puck will be correctly sealed - right to the edge!

[Kiwi_Jonno]

Re: Channelling!?

I now have a Pullman tamper which is great in that its an exact fit etc, but am still getting side channelling with the Sunbeam em6910.

Has anyone else found this? It is probably 20% improved with the new tamper, but still the rim of the pluck is darker and wetter. I sometimes stop the shot early (before it goes thru middle of pluck say 15sec, and the side of the pluck almost only has been extracted. Often the rim is darker and the very middle is darker. If the shots extracted a little longer then the whole pluck is extracted but I like ristretto shorter shots so makes a yuk coffee with the channelling!

Iv noticed im putting the handle more then 90 degs as it doesnt lock as tight as it first did, would this make a difference? Also if I dose normally, lock and lock the PF, then take it off again without exttracting, there is a trail of grinds up the wall of the PF along sides. This happens if locked at 90 degs or tight. After pulling the shot its even more obvious. I thought this is a sign of a non-fitted tamper, but the Pullman one is pretty much exact.

I dose and tamp to 3mm below top basket, and isnt up to first line on PM tamper. I only tamp once etc.

Does anyone know whats happening? :-?

[luca]

Re: Channelling!?

There is only one answer - get a tamper which fits EXACTLY....

When I did my marathon naked PF research session with multiple different tampers, how well the tamper fit had zero impact on channeling or on the quality of the shots. In fact, Andrew was even able to get a decent shot by tamping the puck with his palm This was with the Synesso group, which is less forgiving than an e61, but probably more forgiving than a sunbeam. Jonnos experience seems to imply that the same is true of a sunbeam, though.

Jonno, I really dont think that theres much to be gained from looking at pucks. If you want some real answers about whether or not you are getting channeling, you need to get a bottomless portafilter. You might be right about channelling, but the more reliable information is probably to be found by looking at the coffee pour and tasting it.

Sudden blonding can be a result of using coffee that is too fresh - did you notice a lessening at all over the week? The other thing that Im wondering is if you can defeat the pump pulse preinfusion on your machine? You might also want to try coarsening your grind slightly and increasing the dose, if you can. Soemtimes I find that some coffees just dont perform well at all as an espresso. Perhaps rather than slowing down your shots you might prefer the taste with this particular blend if you ran them at 60mL/30 seconds, but stopped at a 40mL extraction?

Hope that helps,

Luca

[Kiwi_Jonno]

Re: Channelling!?

Yes, if I speed up the extraction it DOES decrease the channelling in the "spent" shot, but again my preference is for ristretto... If I have the gauge on the sunbeam JUST in the black area, blonding occurs about 12sec once it starts pouring, and about 40ml or less. The coffee flows more evenly thru the pluck so it actually taste better even though under extracted! Normally

I agree about the palm tamp, as I know a barista who - with the single shot basket doesnt tamp at all but just scoops the grinds down with index finger making a hollow. In theory it shudnt work but tasted nice!

...so norm the extraction is well into the black area for the shots im TRYING to pull but getting the channelling. I agree the naked PF wud be good to see whats happening, but the pluck tells the story to? Basically its flowing all around the sides/bottom and then thru middle end of shot. The pluck is sometimes "wet" around the rim, but normal in middle, and has the screw showerscrean mark etc.

Am curious, is it normal/ is it ok, if after you polish, and lock the PF it pushes grinds up the side of the basket 1-2mm? This is before extraction...

[Kiwi_Jonno]

Re: Channelling!?

Oh and iv tried freshly roasted, one week roasted, and even stale coffee when ran outa beans all with the same results. IF anything stale extracted better since it ran thru faster but I wudnt wanna drink it lol

Iv been using home roasted as well as Underground Coffee.

[askthecoffeeguy]

Re: Channelling!?

What kind of grinder have you got?

Unless it has micrometrical grind adjustment, you may not be able to get the finesse you need to get the most out of your shot

Sounds to me like you need t fine up your grind a tad, and maybe increase your dose?

If you are up-dosing, then tamping technique will probably have very little impact on the end result as the puck expands to compress against the shower screen anyway.

Cheers,

P

[dsc]

Re: Channelling!?

Hi,

Im having the same problem:| no matter how fine I grind I get blonding at the 15s. I tried everything:

- updosing
- underdosing
- WDT, Stockfleths and other methods
- NSEW
- dose tamp dose tamp (partial tamps, doubles and triples)
- fresh coffee, older coffee, stale coffee
- different tamp force (2kg, 5kg, 15kg, 50kg)
- different dose (from 14g to 20g)

My rig: Gaggia Classic and MDF

I blame my grinder

Its wierd, because today I gave it a try with a really soft tamp (a little more than the tampers weight) and it looked almost the same as with a 50kg tamp. I also tried split dosing with different tamps in the middle. It seems to flow slowly at first, makes a centered cone and after the magic number of seconds - 15 - it goes blond.

Its funny because most people adviced to change my tamper to a Pullman. I see you already did it and it doesnt seem to work anyway, so it must be something else.

Some people also suggested to grind finer, but it also doesnt work. I almost choke my machine, to get a blond stream after around 20-25s (and because it drips for the 15s, I get less than 40ml in the cup after 30s, plus the coffee is overextracted).

I get the same looking pucks as you do, black near the edges, also solid and dry.

Cheers,
dsc.

[TC]

Re: Channelling!?

Hi,

Im having the same problem:| no matter how fine I grind I get blonding at the 15s. I tried everything:

- updosing
- underdosing
- WDT, Stockfleths and other methods
- NSEW
- dose tamp dose tamp (partial tamps, doubles and triples)
- fresh coffee, older coffee, stale coffee
- different tamp force (2kg, 5kg, 15kg, 50kg)
- different dose (from 14g to 20g)

My rig: Gaggia Classic and MDF

I blame my grinder

Its wierd, because today I gave it a try with a really soft tamp (a little more than the tampers weight) and it looked almost the same as with a 50kg tamp. I also tried split dosing with different tamps in the middle. It seems to flow slowly at first, makes a centered cone and after the magic number of seconds - 15 - it goes blond.

Its funny because most people adviced to change my tamper to a Pullman. I see you already did it and it doesnt seem to work anyway, so it must be something else.

Some people also suggested to grind finer, but it also doesnt work. I almost choke my machine, to get a blond stream after around 20-25s (and because it drips for the 15s, I get less than 40ml in the cup after 30s, plus the coffee is overextracted).

I get the same looking pucks as you do, black near the edges, also solid and dry.

Cheers,
dsc.

Hi dsc,

It could be so mahy different things- I suspect it may be your machine...

If it was an e-61 Id be looking at pump pressure, restrictors, temp. at group head and finally, the coffee...It would be very interesting to get a thermocouple in with the puck and also a p/f pressure gauge....I suspect that it may just be limitations of your hardware....

2mcm

[dsc]

Re: Channelling!?

Hi 2mcm,

we already discused my problems with my rig in a seperate thread, which was started by me sometime ago. I dont want to steal Kiwis thread, so Im just gonna say that yeah I think it may be my rig limitations. I tried so many things and nothing worked (I forgot to mention setting my OPV to 9bars).

Im really curious whether Kiwis gonna find a solution to this problem.

Oh and thanks for the support 2mcm

Cheers,
dsc.

[Kiwi_Jonno]

Re: Channelling!?

Hmm looks like were in the same boat, dsc. I to have tried lite/heavy tamping, under/over dosing.

I took showerscrean off cleaned and made sure was fitted right etc. THe Pullman tamper was definitely an improvement, but something is still causing channelling down the side. Weird thing was, about 3months ago the coffee was nice! I didnt inspect the pluck, and maybe im fussier now, but the coffee is hardly drinkable.

Am gonna put 3kg of beans thru it testing, and if machine doesnt make nice coffee somethings gotta go! lol

Light tamping and over dosing seems slightly better so far.....