I think I know why. I first watched the video, and was sold on the idea. Then read what the offer is in the $35 tier, and finally scrolled down to $90 barista set.




This is the image I had in mind when anyone says 'sieve'.



So naturally I thought 'Rafino' refers to the bamboo lid+bottom without holes, and the 'sieve' is as you see above. Had I read the description in detail it'd be clearer.

TLDR: my bad for not reading carefully.

Congratulations on getting funded. Enjoying this thread a lot.

Boldjava wrote:Like Hank, I grabbed one.

8 of us homeroasters gather monthly in my place to cup and learn. What will we do with the Rafino?

* Raffle it off randomly, as we have split cost
* I will present two blind cups, one sifted and one unsifted (my grinder is the Macap MC4).
* Might also dig out a whirly-gig blade grinder for chits and giggles to see how it compares using the Rafino

We'll see if we can discern cup differences. I go into the effort without preconceived opinions. Will be a fun learning experience.

Just wanted to point out that they will be releasing videos in cooperation with the guy from propeller in order to show how the brew parameters change when removing fines. Just wanted to encourage you guys to have someone practice with it for a while before the cupping challenge:)

Great news about the funding, it's the first time I back anything on kickstarter.
I see that they are well above the goal now and has more than 700 backers.

nickw wrote:Imho, it's not the fines which are the biggest problem (as they say in the video), it's the boulders.

This is something I've experienced too. Maybe not the right thread to start a discussion about sifting in general but wanted to mention that
it's been a surprise for me that overall I have enjoyed coffees more when sifting away only the boulders.
Felt the coffee often lacked depth/complexity when I also took away the finest particles.
(no blind testing or any sound scientific approach, just based on my own tastes from brew to brew with many different coffees)

Speculating, but there could be several good reasons for this.
- Maybe I was underextracting the main portion of the grounds to begin with because of too course grind setting and/or too low water
temperature (?), and that when leaving the finer particles in they extract fully and add balance/depth.

- Less fines in the coffee bed->less clogging of the filter of fine particles and less binding between bigger particles->increased flowrate of
water through the bed of coffee->less contact time for water->more prone to underextraction

- in my experience the amount of fines removed varies a lot depending on how long/aggressive coffee is sifted->poor consistency between
brews->variable results

- Maybe my roasts for brew in general have been a tad underdeveloped(?)

day wrote:Just wanted to point out that they will be releasing videos in cooperation with the guy from propeller in order to show how the brew parameters change when removing fines.

I look forward to seeing that, thanks for the info.

Have had an ek43 for about 2 months and the grind consistency is of course a solid step up from my major and vario, so I haven't had
the same need for sifting and only tried it a couple of times so far. The amount of boulders in the grind range for drip was only about half
with the coffees I used, or ca. 2,5-3 grams pr. 50 grams.

Don't think I'll ever bother sifting for espresso but really looking forward to get a Rafino kit to be able to do it faster, with more presicion and experiment with different grind sizes/ranges for drip.

Ps. I measured the volume of 10g coffee ground for drip to ca.15 cubic cm, (a washed burundi at city+ roast), so 60-65g of grounds
should be ca. 100 cm3 or around a third the volume of the top chamber of the rafino if my calculation is not too far off.
It will definitely take some shaking to sift grounds for a whole litre of coffee in it so might be more effective to divide into two portions.
Maybe the people behind it could comment on this?

I backed the $50 level. I was completely disinterested because I only make espresso and espresso drinks. However, this small investment might get me drinking and enjoying more coffee. It'll go great with the Invergo... when we get it.

I also think this might make cold brew even better!

Looks like the company have been listening to you guys because they've added a future target for espresso filters if they get enough backing!

I hope they reach the 100K target. The espresso sieves will be so worth it.

Really appreciate the feedback everyone.
We are so exited to have the funding in place to bring the Rafino to life. Also sorry for not responding sooner but are a small team and shifting our focus on setting up for production, we want to get this in your hands asap.

There were a couple of questions that I want to try to answer

How are the sieves attached?
The sieves will be stamped with a lip with a negative draft angle (something like a spring clip), this will make them snap in place in the Rafino body. They are designed to be easy to remove but won't fall out or shake free once snapped in place. This is a common fitting technique in manufacturing, however without specialized tooling it's hard to make on a one off prototype. That's why it's not really shown in the video and in the prototype.

What's the volume of the Rafino and how much coffee can it sift?
We design it to be used for single serving sized coffee which is generally under 25g of ground coffee. The Rafino will hold a lot more; close to 100g, but sieving requires some empty space for it to be efficient. Also keep in mind sieving efficiency and time will greatly depend on the amount of coffee, the size of sieves and the coffee you are using. In some cases if you want to do a lot of coffee (say over 50g) it might be faster to do it in multiple portions like RedMan suggested.

Better results with a better grinder?
Yes, but it depends on a number of factors. In our tests grinders produce a larger distribution or more uneven grind in the coarser the settings, higher end grinders are significantly better in finer grinds and less so in coarser grinds.
The main purpose of the Rafino is to be able to achieve a consistent grind and customize your grind profile regardless of grinder. In a way I like to compare the Rafino to a timer or scale, you can brew coffee without them but they are very useful tools to get everything right.

Sieving for espresso?
To me there are three components to this question, will sieving for espresso be effective, will it be efficient and is it worth it?

I'll start with the effectiveness. As this is a newish subject there is a lot of experimentation that needs to be done for really conclusive results, but from our test; removing the chaff and larger particles, did have a noticeable effect on the taste of the espresso. As others have mentioned the larger particles will not extract the same as the smaller particles and the extraction yield for those particles will be different, they will be under extracted and impact the taste. The larger particles also effect the way the water flows which will change your shot time, extraction and taste. Looking at some particle distribution graphs for espresso grind like the one posted form Socratic Coffee it seems even the best grinders produce those larger particles relative to the mean, so I would argue that sieving will make the extraction more even and is effective.


The second component and one of our concerns with offering sieves in the lower then 300um sizes is a compromise in sieving efficiency. Unlike things like gravel or sand, coffee particles are very light and have a high electro static charge which poses major challenges in sieving. While we have found that the flat etched screens we use to be far more efficient and precise then the mesh sieves there is still a point where the holes get clogged faster then the coffee falls though. Again as others have mentioned competition baristas have used sieves as small as 150um but looking at that same espresso coffee grind distribution graph there is not many grinders that can grind that fine. So while it will work there is a compromise to be made and the sieving time will be longer (I'll give some specific examples soon).

The last part is to quantify those two components in terms of, is it worth it? Again this depends on a lot of factors such as what equipment you have, how much time you are willing to put into getting that "perfect" shot. So this is very individual and is definitely not for everyone, but for a lot of us that spend countless hours perfecting coffee, it just might be


With that said I want to get your feedback on the espresso sieves stretch goal. We are thinking of offering a 200um, 250um, 350um sieve beyond the 300um and 400um currently offered. Putting that on the graph above gives us something like this, red being current sieves, magenta being the proposed sieves.



Let me know what you think and if there is anything I missed.

Thank you

I personally think it would be the wrong path to pursue espresso as is. However, for fine grind aeropress and small batch v60etc brews where the 200/250 might be beneficial to just eliminate fines without letting out too much grinds, that would seem desirable. Just my impression. I mentioned it in the comments section as well on the Kickstarter, but I would be wary of adding individual sieves or 200-250 sieves for addition to all tiers. I for one would probably drop my commitment, since each 100um sieve seems unnecessary, but 400um seemed a bit too big. At 16 more dollars the main goal for me was to get the 300um, the extra three were just extras, so I went for the barista. No need to do that anymore if
It is available for a cheaper package.

adamkrupa wrote:Again as others have mentioned competition baristas have used sieves as small as 150um but looking at that same espresso coffee grind distribution graph there is not many grinders that can grind that fine.

The graph does not provide anything resembling that information.