Korean espresso machine manufacturer El Rocio have been testing some new transparent portafilter designs. There is a photo of one design on a blog here, and lots of information and photos at Black Water Issue. They are still in the prototype stage, but apparently plan to make it commercially available in the future.

I can't even get my Chrome browser to translate the Korean. But I admire developments like these. I'd hope to see Stephen Sweeney mentioned somewhere, since he did a great deal of the trailblazing.

I think there'll be a lot of interesting dialogue that disseminates from things like this.





* edit: I just noticed the proper attribution to Stephen on their blog. I've checked it out via Facebook before, it's quite interesting and I wish we could get a thorough English translation, because they're really doing a lot of tests and experiments.

They undoubtedly have much better skill levels and machine tool equipment than myself and they appear to be making a very interesting, good looking device. Kudos!

I notice that the water volume is not in the direct comparison to a 58mm PF. I wonder what they used for a basket? I used a 58mm PF Basket with the bottom cut out leaving all the OEM holes. I also left the I.D. the same as a 58mm PF Basket.

I wonder what they are projecting for a price for one of the little beauties??

On their website they have design v1 and v2.

V1 is what's in the video above, and seems like a very solid design with the metal and bolts holding the transparent chamber in place. Seems like a really solid design, so I hope it will survive lots of testing.
V2 looks like plastic attached to metal, but it also looks like it may suffer the same fate as earlier designs like Steven Sweeney's original. Perhaps they've found something that will hold up to the pressure and heat?

Every one of these naked basket videos gives a little more insight into what happens in there. Great stuff!

Tamping makes the wetting of the grounds more consistent and even, top to bottom. And since temperature and pressure also vary top to bottom, I think that such consistency is preferable.

I'd like to see a video with and without preinfusion. I suspect that the without case results in slightly more compaction.

According to their engineer, new prototypes are testing.
It will have a similar structure to the standard filters that we used to using, so it is more analogous to realistic phase.

Devin Lee

More information : The prototype#1's bottom filter(is showed in clip) is made whole new design. They didn't use existing filter basket so bottom plate should be made with new design like VST looks. It have 641 holes and each diameter is 0.3mm(Gap distance of each holes is 1.8mm). Nowdays, it have a quite much headroom space as realated to durability. But next version will have a modified headroom height.