Safety issue? - Green spots on copper and scale inside La Pavoni boiler

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#1: Post by peter_bjerg_copenhagen »

Hi all

My first post here.

After descaling my La Pavoni Europiccola boiler (with 50/50 white winegar/water mix heated up to near boiling, then waited 1 hour before several clean flushes of water), I notice that inside the boiler, the copper has visible green/white/black areas. And also the heating element still has some scale still.

I would like to know, if this is the dreaded "sulphate scale" and not "Carbonate scale", which cannot be removed with weak acids, and which can occur if too much sulphur or chlorine is in the water. I read about it in various posts, eg the copied post from 2014 by "rpavlis".

But is it this bad kind of scale on the heater? and the green areas on the copper, is that bad and unhealthy, and whats to do about it?

rpavlis wrote:If one can look into one's espresso machine's boiler, one should do so frequently to be sure there is not scale forming. Carbonate scale and sulphate scale have a similar appearance. However, carbonate scale will dissolve fairly quickly in white vinegar or citric acid solutions. Sulphate scale dissolves no better in white vinegar or citric acid solutions than it does in purified water. There are commercial sulphate scale removing products. Some have EDTA. There are other materials too. I have always thought that when people steam a lot of milk drinks it is best to use sulphate free water. It is always best to use chloride free water. The thing that is really good to have in espresso water is bicarbonate ion--as explained earlier, it makes the water slightly alkaline, right at the pH of greatest copper oxide coat stability, and it reduces the acidity of the product. By coincidence the pH that is best for boiler stability tends to be excellent for flavour.