Operation Manual

44
Too Slow
Here is a pull that lasted a long time and yet hardly an ounce was produced even though this was a double
basket and we should have double that amount in the cup. This photo was taken after about thirty seconds.
Notice the dark, viscous flow which is a sign of over-extraction. This will usually result in a harsh taste that
few would enjoy. Possible causes of this slow flow extraction could include:
• Coffee ground too fine. Adjust the grinder one or two clicks (or settings) more coarse and try again.
• Worn or inaccurate grinder burrs. Old, worn grinder burrs or a low-quality grinder can create a lot of
dust in the grind. This dust migrates towards the bottom of the basket during extraction and clogs the small
openings, dramatically restricting the flow of water. This also results in a very bitter beverage because of
the “fines” that end up in the cup.
• Low pump pressure. Although not likely, this can be caused by a mis-adjusted or faulty pressure relief
valve on the rotary pump.
• Clogged filter basket. If enough of the holes in the filter basket are clogged it can slow the flow sufficiently
to make proper extraction difficult or impossible. Wash and dry the basket and examine it by holding it up
to a strong light source. If clogged, soak it overnight in espresso machine cleaner (See Chapter 19). If that
does not correct the problem you can try using a pin to carefully clean the holes. If that does not work, re
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place the basket.