Well l am speaking from my experiances wich is not to be taken too generaly. I mentioned before my wood grows on quarz sand and l suspect lots of silica in the ash, l always get lots of slag. Eaven in my house wood boiler.
Anyway, this stile reduction basket required a steel scraper installed, turned a couple of times prior to lightup to break the clumps. And frequent emptying/char screaning.
Perhaps for others, this might work. Dusty ash does flow sideways to a point.
The way l solved the problem was to lower the perforated cilinder, thus achiveing a updraft reduction zone.
Perhaps Chris culd split this topic, we did invade Toms topic quite masively.