frankmoss wrote:Often people buy citric acid from a home-brewing shop, so there are no directions for making descaling solutions. In this case, the manufacturer would have no idea what concentration to use. In this case, I use OE's recommendations, which are 1 tablespoon per liter. But weaker solutions work, but more slowly.
Paul Pratt states he makes up to a 20% acid solution (sorry couldn't tell you how to measure this), with the caveat that he has years of experience restoring espresso machines.
Higher concentrations of the acid solution, not watched carefully can cause damage to delicate finishes, quickly eating through the chrome on plated brass parts. The acid can also cause galvanic corrosion where two dissimilar metals meet (http://en.wikipedia.org/wiki/Galvanic_corrosion
) and quickly destroy your parts.
The steam boiler on my Linea has such a solid mass of mineral deposits in it that I opted to use a low strength solution to slowly break down the minerals. The boiler has been soaking in the citric acid solution for days. I take the tank out and scrub the crud with a green abrasive pad every day to speed the break down.
As for the other parts, I used hot water and watched everything as it steeped in the acid. As soon as the minerals were gone the part came out. The acid works more quickly with hot water than cold. Try using a cooler with the hot acid to maintain the temperature. With the steam boiler, I've been able to keep the bath water above 100F over night in the cooler.
Disclaimer: I am not an expert. The opinions stated in this transmission are strictly the opinions of the author and are probably incorrect on many levels. But they worked for me.