# Blonding



## lucky13 (Dec 30, 2011)

I've been scanning through a few old threads and I can see references made to 'Blonding'.

I see it referenced as a negative thing. I assume from what I've read that it's a change in colour of the extraction.

Could anyone offer me an explanation of what it is and what it means?

If I spot this should I stop the extraction?


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## fatboyslim (Sep 29, 2011)

This may help you diagnose extraction problems

http://www.home-barista.com/espresso-guide-diagnose-extraction-problems.html

Blonding is probably the most common extraction problem and is caused by the most common technique flaw (once you get past dialing in the grind and temp surfing)...distribution and tamping.

If you allow a perfectly distributed shot on a very expensive machine to run for 40+ seoncds the colour of the liquid coming out of the spouts will be like a beige/blonde colour.

This is because all the dark desirable oils have already been extracted from the grounds and all that is left is the bitter remnants.

If you distribute the coffee grounds in such a way, in the basket, that the pressurised water can more easily move through some areas over others; the nature of water dedicates it will choose this path.

What this means for your coffee is that some areas will extract completely whilst others not at all, meaning you will rapidly reach the over extracted/blonding stage while much of the desirable dark flavorful oils remain in the basket.

This is obviously bad but if you quickly google the Weiss Distribution Technique (using a paper clip to fluff your grinds up) and use a good tamping technique, blonding shouldn't be an issue for you.

Dare I say it, I even give the portafilter a quick tap with the handle of my tamper to knock the grounds off the side but some people think this causes additional channeling.

Its all trial and error.

Hopefully this helps










EDIT: This chart makes reference to the blonding point.


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## RolandG (Jul 25, 2010)

Blonding is a rather loose term. Basically, during a shot, the water is forced through the puck of coffee. To start with, there is a lot of material that can be extracted from the puck into the water, so the espresso is a dark brown and looks very thick, and starts dripping from the portafilter slowly. As more water passes through the puck, the easy to extract material has already gone and the amount being extracted is less. This means that the espresso coming out is somewhat lighter in colour, and flows more quickly. This continues as the shot goes on, with the shot becoming paler and thinner. The shot appears very yellow/blonde, and the shot is also thinner - the espresso streams will start to flick around rather than hanging downwards. This is the "Blonding" process. Stopping the shot at the start of/shortly after Blonding is generally best for taste, because this balances out the flavours. Shots stopped before Blonding are generally sweet but acidic. Shots stopped significantly after Blonding are generally less acidic but more bitter. Where the exact best point is varies between different coffees and also depends very much upon your personal tastes - it's not an absolute, just a helpful guide.


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## jork45 (Mar 13, 2012)

Great explanation and lets me understand a lot better,thanks


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