# Lighter Roasts



## Gavin (Mar 30, 2014)

Hi,

My classic has the OPV adjustment and has a PID controller. Coupled with my Niche I get some absolutely delicious coffee out of my little beast.

However, this is almost exclusively using dark or medium/dark blends (which i prefer fortunately), but for some reason my classic seems to destroy anything approaching the lighter side.

Using lighter, jazzier, single origin beans I find in almost impossible to dial it in correctly. It usually results, loads of channeling, messy puck post shot and a very sour shot.

So my question is: Is this owing to the Classic's lack of pre-infusion capability (which I can't really do too much about) or is there something I can do to improve my extractions of lighter roasts?

Many thanks,


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## Bacms (Jul 25, 2019)

I also have a gaggia classic with a PID but paired with a Vario grinder. It is hard to give you any advice without a bit more of detail but the classic shouldn't have a problem with anything but the super light roasts. In fact I frequently use mine with light roasts as that is my preference.

Lighter beans tend to be more difficult to extract and need a bit longer of a resting time after roasting so make sure you wait a bit before using them. They often also need a finer ground than most (had to recalibrate my Vario) and you can also raise the temperature a degree on two on the PID if you are still getting very sour shots. They also often benefit for slightly longer ratios than 1:2. How much coffee are you putting in, how many grams are you getting out and what sort of time are you aiming for. But in any case you shouldn't really be getting channeling unless you have uneven grinding/distribution so it may come down to technique on your part.

As for the pre-infusion on the Gaggia there are some ad-hoc ways of "achieving" it although I am not of fan of any (they lack control and repeatability is trickier) of them so I try to get away from them. But to achieve pre-infusion you can and open the steam valve at the start of the shot (see video below) or start the brew and turn the machine off at 1/2 seconds and then turn it back on after 5 seconds.






or turn the machine off a few seconds are the


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## Gavin (Mar 30, 2014)

@Bacms Thanks for the reply.

I don't seem to have any prep related issues with darker roasts.

As far a weight is concerned, I started with 18g trying to get 36g. But noticed it was pissing out regardless of the grind setting. Extraction would usually start off very slow when finely ground but then speed up quickly, flooding out of the portafilter.

Also, 18g of the light stuff seemed to sit very low in the 18g VST compared to 18g of dark stuff, so I ended up whacking about 21g in the same basket which seemed to help a bit. So about a 1:1.7 ratio,.


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## Bacms (Jul 25, 2019)

Gavin said:


> I don't seem to have any prep related issues with darker roasts.


 The reason the light roast may reveals previously unseen is that you need to grind finer creating more resistance to the water flow so more pressure builds on top of the puck so any path of easy flow will be exploited. With coarser grinds and faster shots the puck may saturate quicker so no channeling visible.



Gavin said:


> As far a weight is concerned, I started with 18g trying to get 36g. But noticed it was pissing out regardless of the grind setting. Extraction would usually start off very slow when finely ground but then speed up quickly, flooding out of the portafilter.


 But does it mean you never managed get to get to say a 30 seconds shot? Have you ever adjusted your OPV?



Gavin said:


> Also, 18g of the light stuff seemed to sit very low in the 18g VST compared to 18g of dark stuff, so I ended up whacking about 21g in the same basket which seemed to help a bit. So about a 1:1.7 ratio,.


 I would not dose more keep dose consistent and play with grind and ratio. Try a longer ratio such as 1:2.5/3. Longer ratios will extract more even though they probably are one of the weaker spots for the classic as the longer the shot the more the temperature will drop and the small boiler isn't ideal. Although I have not actually seen temperature data on this to properly back it up


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## kennyboy993 (Jan 23, 2017)

I can't imagine getting the best out of light roasts without some sort of control over pre-infusion.

If you're sure you're getting channeling then you have the problem I had before having a machine with repeatable pre infusion capabilities - the grind is just so fine

Sent from my iPhone using Tapatalk


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## ashcroc (Oct 28, 2016)

You can fit a dimmer to the pump & an inline manometer to get repeatable pre-infusion on a classic.


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## Bacms (Jul 25, 2019)

ashcroc said:


> You can fit a dimmer to the pump & an inline manometer to get repeatable pre-infusion on a classic.


Is there any details on how to achieve this?

Sent from my SM-G950F using Tapatalk


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## ashcroc (Oct 28, 2016)

Bacms said:


> Is there any details on how to achieve this?
> 
> Sent from my SM-G950F using Tapatalk


There quite a long thread on fitting a dimmer here. It's worth reading through to the end as it's been improved upon since the thread started. Pretty sure if you search, you'll find something on fitting a manometer too but it's just a big hole to drill in the case & a bit of plumbing.


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## Nikko (Aug 20, 2014)

If you do not like the taste you are getting, no amount of preinfusion or whatever will make it enjoyable for you.


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## Pants001 (Mar 13, 2019)

I buy 2 different blends, a dark roast and medium roast......for the Medium (as others have said) i make the grind slightly finer, and temp up marginally.

Also make sure you check your screen. I recently removed / cleaned mine and it was ok on the side showing but tar build up on the inside with no daylight showing through the holes. Was a noticeable difference after a good scrubbing.


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## Mrboots2u (May 10, 2013)

Do you like lighter roasts as filter coffee or just not at all....


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## Gavin (Mar 30, 2014)

Bacms said:


> The reason the light roast may reveals previously unseen is that you need to grind finer creating more resistance to the water flow so more pressure builds on top of the puck so any path of easy flow will be exploited. With coarser grinds and faster shots the puck may saturate quicker so no channeling visible.


 Makes sense



Bacms said:


> But does it mean you never managed get to get to say a 30 seconds shot? Have you ever adjusted your OPV?


 Shot usually runs fast even when grinding fine. OPV has been adjusted



Bacms said:


> I would not dose more keep dose consistent and play with grind and ratio. Try a longer ratio such as 1:2.5/3. Longer ratios will extract more even though they probably are one of the weaker spots for the classic as the longer the shot the more the temperature will drop and the small boiler isn't ideal. Although I have not actually seen temperature data on this to properly back it up


 I'll try it


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## Gavin (Mar 30, 2014)

kennyboy993 said:


> I can't imagine getting the best out of light roasts without some sort of control over pre-infusion.
> 
> If you're sure you're getting channeling then you have the problem I had before having a machine with repeatable pre infusion capabilities - the grind is just so fine
> 
> Sent from my iPhone using Tapatalk


 This is what I'm thinking


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## Gavin (Mar 30, 2014)

ashcroc said:


> You can fit a dimmer to the pump & an inline manometer to get repeatable pre-infusion on a classic.


 Looks like I'd have to my pump first and then do the rest of the faff. Not sure I'm technical enough to no balls it up.


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## Gavin (Mar 30, 2014)

Mrboots2u said:


> Do you like lighter roasts as filter coffee or just not at all....


 I do. When i get a light roast, after realise I can't get a decent espresso I just grind it for French Press.


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## Mrboots2u (May 10, 2013)

Pull your shots heavier in weight


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## Rhys (Dec 21, 2014)

You can also stick a jug under the steam wand and open it up a bit when pulling a shot. It'll drop the pressure to the group-head. If you put a pressure gauge on the portafilter you can measure where it hits around 3 bar and mark the side of the body/control knob to give you a starting mark. The it's just a simple case of opening it up, switching on and when drips appear, slowly closing it to get full pressure. Just pour back any water in the jug back to the tank. That's what I did with my first Classic and worked quite well.


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## Gavin (Mar 30, 2014)

Mrboots2u said:


> Pull your shots heavier in weight


 I went up to 21g in an 18 basket. which seemed to have better results. But someone above said not to do that.?‍♂


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## Gavin (Mar 30, 2014)

Rhys said:


> You can also stick a jug under the steam wand and open it up a bit when pulling a shot. It'll drop the pressure to the group-head. If you put a pressure gauge on the portafilter you can measure where it hits around 3 bar and mark the side of the body/control knob to give you a starting mark. The it's just a simple case of opening it up, switching on and when drips appear, slowly closing it to get full pressure. Just pour back any water in the jug back to the tank. That's what I did with my first Classic and worked quite well.


 I'll try this. Thanks


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## Bacms (Jul 25, 2019)

Gavin said:


> I went up to 21g in an 18 basket. which seemed to have better results. But someone above said not to do that.?‍♂


 He is referring to brew weight like I mentioned. So rather than try a 1:2 ratio of 18g->36g extend that to something like 1:2.5 so 18g in to 42.5g of liquid


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## Gavin (Mar 30, 2014)

Bacms said:


> He is referring to brew weight like I mentioned. So rather than try a 1:2 ratio of 18g->36g extend that to something like 1:2.5 so 18g in to 42.5g of liquid


 Ah, apologies. I'm with you now.


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