New: headspace reduction kit, with surprising refractometer results
Shower screen headspace reduction kit (UPDATE: OUT OF STOCK, SOLD OUT)
Reduces 2mm of headspace above the puck. Causes a similar effect on espresso that a puck screen on top the puck does, but without the additional cleanup. Less headspace causes a denser coffee puck, for a more traditional, thicker espresso with less channeling. Especially suitable for medium to dark roasted beans. Includes the IMS SI200IM shower screen, a Decent-designed CNCed washer and mounting screw.
The story behind this…
The Decent community is always looking to emulate the style of certain espresso machines, especially the classic lever machines. A whole ecology of products have sprung up around “thick, classic shots”,
- with “waisted baskets” (thinner at the bottom, for a thicker puck, imitating the smaller basket diameters of some levers
- headspace reduction kits (such as from SWorks Design)
- and metal mesh puck spacers (such as Flair's)
Different machines from history have a different amount of headspace above the coffee puck. Less headspace impedes blooming and swelling, but it also forces the puck to become denser, and more homogenous.
Generally, people feel that less headspace is better for medium to dark roasts (more body), and more headspace is better for light roasts (better clarity, greater extraction %).
A few months ago we released a set of new group head parts that made the DE1 follow the E61 headspace standard. However, there are machines out there with even less headspace, and they do make classic, thick shots, easier.
IMS makes two shower screens that work with the Decent. Paul was pulled shots using the “80s profile”, which is lower temperature (80C down to 72C). This profile in intended for medium to dark roasted beans, and intentionally uses a lower temperature to not extract unpleasant burnt tastes, while getting more fruit and medium chocolate. It's a 1:1 extraction (22g in, 22g out), fairly slow flowing. Here's a sample shot:
What surprised us, is that in our ten refractometer tests with this profile, that the headspace reduction resulted in a significant increase in % of coffee extracted:
Paul posted these comments about the shots:
- The SI200 created more stable extractions. Most likely due to the reduced headspace increasing the puck integrity via limiting the expansion of the puck.
- Less channeling was a result and would help explain the higher yield.
- Aroma was more complex and sweeter.
- Swirling was more viscous as it clung to the cup more ( will get a video of this)
This is especially interesting because other research I've seen has shown that for light roasts (and typically 1:2 ratios), that more headspace increased extraction %. Now we see that at least in some situations (shorter shots, that reduced headspace
Updated 2023/12/19