In my review post in the EspressoForge - First Impressions thread I posted a conjecture about why I need to grind considerably finer on the Forge to achieve the desired flow rate having to do with water wetting the puck at "gravity pressure" for a considerable amount of time 5-10 seconds at least before any ramp up in pressure. Others who have used the same device with very light roasted coffees have experienced the same need to grind finer compared with a "soft and pleasant' espresso with light roasted coffees.

This weekend I wanted to play around with emulating this same sort of "preinfusion" on my other machines by just pouring hot water on the puck a few seconds before I lock it in. I also wanted to start a discussion thread on it to glean input from others about this topic.

I am certain that this will change the flow rate, as a quick experiment on my Ascaso Pro at the office verified that pre-wetting my puck caused a faster flow rate, allowing me to grind at a fineness that would have choked the machine before. I feel as far as taste goes however I would fare much better with my lever machines.
The shot profile I will be attempting to emulate is
Grind finer than normal
X seconds of wet puck preinfusion at no pressure <-pouring hot water on the puck and then locking it in
Y seconds of preinfusion ramp up (1 bar boiler pressure in the case of my Faema President)
Pulling the shot at a typical lever-style declining pressure profile.
Taste it <-blind tasting if I can get my assistant to help me out with this.

If the object is to wet the grinds (so they don't compact so much) and do as little as possible in terms of starting the extraction process, consider pouring cold water on them. You might do better than machines with pre-infusion.

Using cold water, I hadn't thought of that, mainly because the idea occurred to me while using a manual pour over espresso machine. We've been experimenting with hot water, we will have to try with cold, but even with the hot the preinfusion time already makes a cooler drink. It definitely allows us to grind finer for the same flow..

I'd like to chime in: When I read Dominick's first post about Forge I got a flash! I decided to try doing a mini pourover into my Caravel basket before pulling shot. I have been getting sour shots on some SO's. The shots had been typically underextracted-no sugar, reduced chocolate and I couldn't solve it with the grind, dose or temperature. I even tried "start dumping".

My first attempt, I tamped then did tiny wettings, letting water absorb until it seemed saturated. Low and behold, more chocolate! Not great.
I did a second attempt-(I forget what I changed) and the shot was amazing-really intense ristretto with all the layers.

Then I decided to really grind fine almost to Turkish, reduce the dose to 7g, don't tamp and use a WDT with a needle to fully saturate the grounds. I'm still playing but I can say this COMPLETELY CHANGES the taste profile of the Caravel shots. I'm not sure if it improves anything, but it sure is interesting.

What's exciting is this was sychronistic with a discussion with Brandon at Slayer who described Slayer as a Chemex followed by 9Bar, conceptually.
(And Slayer is full-on into the concept of pre-brew!!)

NEXT: I was just exposed to Matt Perger's WBC video, which is mindblowing: He described the very thing I just discovered with these Caravel shots: something in between espresso and pourover.

This morning I just pulled the most interesting shot yet: I ground Ethiopian Borboya from G. Howell coarser, but 12g and pulled it into a fraozen espresso cup (a la Perger Video). I got all the cupping flavors in order. (shot was a little dry with little finish, tho)

I think this is really worth exploring. I'll repost my PM to Dominick in a second post.

If anyone experiments, please post roast, grind, dose.

Laurence

Re: pre-wetting
Sent: Jun 12, 2015, 9:42 am
From: isaliveart
Recipient: dominico

Dude!! You have introduced a whole new thing! (I think) This AM (and all refers to Voodoo Pharos: I was grinding for Caravel generally between 1/2 revolution from Zero and a full revolution-mostly in between-so here goes):

I'm playing with 3 Olympia Coffeee Africans, 9 days off roast.
1: Birembo from Ruanda (notes-peach, red apple, and black tea)-yesterday with my normal Caravel routine with about 15g at 3/4 rev on Pharos it was undrinkable sour/acid, with Aeropress it was really good -all flavors coming thru.

This Am I grounda couple clicks coarser than 1/2, lightly tamped about 15g and tried to pre-wet and bloom like a pour over: wet the top of basket, wait, add a little more, until no more water would descend. Waited 30 sec or so, locked in the basket and pulled. No crema, BUT I could drink it. The sugars really did start to come out.

Then I decided to grind way finer. Did the same thing with Konga Yirgejeffe and choke it-couldn't get a drop.

Backed off grind to where the previous pull that worked and did not tamp. The pull was Looong, but MUCH more flavor. WOW: intense floral and citrus PLUS chocolate. The pull was one drip at a time and no crema.

Next-I finede the grind a little but cut the dose to 7.5 g with no tamp and pre-infused the hell out it (I switched back to the Ruanda) The pull wanted to go fast (no puck resistance) so I back off pressure and got what was really a really strong pourover, BUT tasted great-all the sour/bright, no chocolate gone.

I'm too caffeinated now, but next will be closer to Turkish grind, but low dose as above.

I can't be sure how deep down the puck the "wetting pour over" goes-but so far this is opening the door to possibilities. First of all I have enjoyable shots from the same beans I had to dump. Second, the chocolate, caramels are coming out better.

Thanks so much. What a noble premise-to get great espresso low, low tech from light roast SO's. Andre's Forge has got to make this easier cause you can let the water sit in the tube as long as you want before applying the piston. I'll keep you posted. Let me know if you start playing with this.

L

I'm interested to see if pre-wetting can or does increase the extraction yields of our espresso.

Question comes from Matt Perger (this probably should be on separate thread) but the ideas of changing the game in this way-grind finer, long pre-pre-infusion should involve increasing the extraction strength to change flavor. He's doing it, supposedly with EK43, which allows I think bigger, more uniform particle size to yield higher extraction ratio's in longer volumes. He's using an expensive meter from VST to program his extraction yields and volumes primarily. He's actually getting higher yields from longer shot volumes. It seems he's turning the espresso machine into a super intense pourover.

I have a $100 brix meter I've never used for coffee so would like help getting up to speed with this.

(Now it's fascinating that Andre has called the Forge an Aeropress on steroids,).

isaliveart wrote:(Now it's fascinating that Andre has called the Forge an Aeropress on steroids,).

I can't remember saying that! But it's a good quote to attribute to it's rightful owner somewhere along the line, otherwise it goes to you!

I was just trying to make an espresso machine, any other capabilities or side-effects that happen to be beneficial are totally luck. I'm hoping they turn out good, but just as easily it could have gone the other way thinking about it.

I've been meaning to try out pre-wetting a puck on my pump machine, but just ran out of coffee today...time to fire up the roaster.

isaliveart wrote:I have a $100 brix meter I've never used for coffee so would like help getting up to speed with this.

It's likely that your inexpensive meter won't have enough accuracy or precision to provide reliable espresso measurements. It definitely won't be able to accurately measure brewed coffee, which has much lower density. Also, you have to convert Brix to TDS, and then TDS to extraction yield, neither of which is simple, and there are US patent restrictions.

This is a highly controversial subject and there are quite a few threads about it on HB -- some of which have been locked due to being repetitive or providing heat but no light. It's not my intent to start another thread about this, but simply to let you know that there are reasons Perger doesn't use an inexpensive Brix meter.

The low cost analog optical 0-32% Brix instruments found on eBay will work, it is a different story when attempting to do this with digital devices. It is not required to convert Brix to TDS and TDS to extraction yield either.

If you mean that a cheap analog Brix meter can tell you whether pre-wetting/pre-blooming increased the extraction yield, then I guess that may be true. But it won't tell you what you really need to know, which is how much the extraction yield changed. The device won't have the resolution, precision or accuracy to do that for coffee, and maybe not even for espresso. And you do have to do the conversion to get meaningful information about the impact on acid-bitter-balance.

And I'm interested to know why you think an analog Brix meter can do something a digital Brix meter can't do.