I was thinking today about baskets and side channeling as I continue to work my basic skills. Side channeling is often caused by not having a good seal between the puck and the sides of the basket, right? Maybe the basket wasn't dry. Maybe a tap broke the seal, or maybe the tamp wasn't straight (making it sealed on one side but not on the other). Some use staub or nutating tamps to avoid the problem. Convex tampers are also aimed at solving this problem.

One of my other interests is art painting, and one thing you learn early on with painting is that your painting surface needs some 'tooth.' In other words, there has to be something for the paint to stick to---to get in there and hold on. That's why canvas is popular for painters. It has all kinds of little crevices for the paint to sink into and create a complex film with strong adherence as it fills all the holes. Try to paint on solid polished aluminum and your painting is a conservator's nightmare (presuming anyone ever cares about it! ). The dry painting will fall right off the metal if bumped wrong!

Anyway, while coffee certainly isn't paint, it made me wonder. Why not roughen up the sides of a basket? When you tamp down, some of the coffee grinds would push a bit into the tiny crevices. Adjacent grinds would be interlocked with those. Might this create more adherence to the side and reduce the risk of side channeling?

You may have all already thought about this, or there's a very clear reason why this is a rotten idea. But just in case I thought I'd mention it.

thats a good idea

maybe i'll take a file to my basket and roughen the edges

Conversely, sides might increase the chance for uneveness in the tamp allowing for even more channeling down the sides. Perhaps the good folks at HB might be willing to sacrifice a PF or two to the espresso gods and do some tests.

Just to be clear, I'm talking about a very slight roughness. Something like the texture of fine-grit sandpaper or what you'd get from sandblasting just to take the smoothness off.

Being in the business of working with all sorts of fabrication techniques, I think sandblasting would be the perfect treatment. Rough, but no pattern.

A dremel with a wire wheel on it will do for a quick test. Used like a hone it won't leave anything with a coherent pattern to it, yet not make the surface significantly rough (not quite like a sandblast, but you get the idea)

I might have to try that with a spare basket and see what I think of the results.....

I have been thinking in the same way, and have been thinking about roughing the inside of the filter.
Keep us updated if you perform any tests....

The shark's skin has evolved to be rough, so that the water does NOT cling to it and it can torpedo through the water with less drag. The same principle has been applied to racing sailboats. It could be that a roughened surface inside the filter might actually increase side channeling, by reducing the cohesion and surface tension. Bring on the experiments

Regards
Timo

Yes. I agree...if it's TOO rough!

The results are interesting. But the smooth side is still the best. Texturing of the side walls through various methods ( media Blasting stamping, abrasing ) have some minimal effect towards stabilization of the puck. The overall result has been channeling. Think of the same as a Cory type glass filter. The water will find a way...........