# Waves, ridges, spirals in coffee dripper



## Phil104 (Apr 15, 2014)

I know the principles behind ridges of one kind or another in drippers, such as the Kalita Wave and the Origami. I have also seen research comparing flat bottomed drippers with cone drippers. Does anyone know of any research that investigates why ridges work and whether there any advantages over one kind of ridge rather than anther?


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## MWJB (Feb 28, 2012)

Ridges are there to ideally stop the paper from forming an airtight seal against the wall of the cone. When this happens, say with an overfilled Chemex, it can stall the brew (where this is a possibility, I stick a steel straw down the Chemex spout to maintain an airway).

In the Wave, the fluted papers (like other flat bottomed basket brewers) prevent this airlock, as well as preventing the paper filter collapsing into the brewer during extraction (seems most common with Melitta/Filtropa truncated cone papers). The Y shape indentation, or welded wire in the bottom is supposed to also prevent airlocks at the base.

It's also why you might see a hole in the base plate of some brewers.

There isn't any significant practical, nor sensory difference between V cone, flat bottomed, or truncated cone brewers, when normalised (same brew size, extraction, grind size) as far as I can tell. Flat bottomed brewers retain more liquid compared to V cone brewers with large holes, at the same grind, but it's not a make or break difference.

Where you don't have a gap to allow normal flow, brewers can stall & take longer to drain completely, this can cause overly long brew times (over 7min), adverse flavours (but not always), and in extreme cases cold coffee (12-13min brews). The only brewer I have seen this in with any kind of regularity (maybe 1 out of 6-7 brews) is the Brewista Smart Steep brewer, which was not designed for pour over brewing, I'm just hacking it.

I severely doubt that there is any advantage, simply because you can usually change something else like grind size, or pour regime to reign things back in. For the aforementioned Brewista, I stick a small French press mesh under the paper to stop it sealing against the brewer floor.


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## Phil104 (Apr 15, 2014)

I'm sorry - I have just seen this characteristically interesting and informative reply. Thank you very much @MWJB. I spent a chunk of today comparing a V60 filter paper in an Origami and a Kalita paper to reach no scientifically sound conclusion, not least because unscientifically, I used a different method so there were different variables (not in brew size and grind size). In any event, both produced a sweet, nicely balanced drink.


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