HB wrote:There's also Section 4,
Water Treatment and Preventive Descaling for Espresso Machines in Jim's
Insanely Long Water FAQ. Below is the relevant excerpt:
Preventive Descaling
Descaling Solution - Generally, a flush through descaler uses about .5 to .75 fluid ounces (1 to 1.5 tablespoons, or 8 to 12 grams) of citric or tartaric (grape) acid powder dissolved in 1 liter of water. This is a 2.25% to 3.5% solution, equivalent to 33% to 50% dilute lemon juice. Cleancaf and other coffee manufacturers' descalers use this formula. Theoretically, these amounts will dissolve about 12 to 18 grams of scale per liter, but that would require leaving the solution in for several days; in practice, it is used for an hour or two to dissolve up to 5 grams of scale.
The formula is mild enough to be harmless to espresso machine components, but it will come out of brass or copper machines with a slight greenish tinge. This comes from milligram levels of dissolved copper and is no cause for alarm.
Five pound bags of citric or tartaric acid cost about $10 at home brewers' or soapmakers' supply stores. This is roughly a 20 year supply.
Descaling Intervals - Know the hardness of the water you're using, and how much you use the machine. Descale when accumulations are between 2.5 and 5 grams. More often is a waste of time, less often may result in scale build up. Check out section 1.7 for instructions on determining your set up's scaling rate.
Single Boiler Machines
For single boiler machines, preventive descaling is no problem, just follow the instructions given by the manufacturer. In general, this involves filling the boiler, letting the solution work for about ten minutes, and replacing it by running it out of the steam wand under pump pressure. This procedure is repeated three to five times, until about a liter of descaler is used up. Then the machine is flushed with water until any taste is gone.
Or if you prefer, my own...
Descaling espresso machines in a nutshell:Preventative descaling of a single boiler (Rancilio Silvia et al) is trivial - fill the boiler with descaler (or CleanCaf), let it sit a spell, flush the boiler a few times with fresh water. Descaling an HX - not the steam boiler - is even easier. Fill the HX with descaler (citric acid), let it sit a spell, flush a few times with fresh water. Since the HX has less volume then the boiler, it fills and flushes in a jiffy.
Preventative descaling of the steam boiler is a pain because not all machines include a drain tap (e.g., like the Cimbali Junior), forcing you to use the water tap as the drain. The manufacturer does this to save costs. BTW, it's not absolutely necessary to force overfilling by disconnecting the auto-refill. You could also tilt the machine slightly and the autofill should kick in long enough to cover the scale line.
Choosing not to do preventative descaling is unwise. Ask any vendor what is the most common cause of espresso machine failure, commercial or otherwise - they'll all say "scale". If you want to keep your HX espresso machine running well and not spend a lot of time on maintenance, at least run descaler through the HX. It shouldn't take more than 5 minutes once a month.
by gabriel on Mon Oct 29, 2007 5:38 am 
