De-scaling Espresso Coffee Machines

Lever Machines

Use citric acid  (about 30g/litre  for a 0.125 mole solution). Pour it into the boiler a little above the normal level. Switch on, let it get to pressure With a jug under the steam wand, open the steam tap, solution should be ejected into the jug (if not put some more solution to raise the level in the boiler) and shut the tap. Put a jug under the group, raise the lever and allow the mixture through the group. Switch off and leave the machine to cool, . Empty the mixture out of the boiler, check the scale has been remove by using a small torch to see into the boiler (If not make up more solution and repeat, it may be the pH inceased and the scale has not all been removed or sodium citrate has come out of solution) 

When satisfied, rinse out the boiler a few times and to be really thorough, dissolve a tablespoon of sodium bicarbonate  (bicarbonate of soda) to a jug of hot water and fill the boiler, switch on and repeat the process as with the acid. Rinse out with water and use as normal. Use a dish washer for the filter and portafilter (remove the handle and threaded bar)

Pump Machines

Citric acid is added to water in the water tank. Leave the filter holder off, put a bowl under the boiler outlet and switch on the pump for about 30-45 sec to fill the boiler with the mixture. Open the steam tap to get the mixture into the valve and steam assembly and shut the tap. leave for 30min and pump again for 30-45sec to refresh the solution (keeping the pH high in the boiler and avoiding water insoluble sodium citrate to form), continue till the reservoir is used up. Switch off, empty and rinse and refill the water tank with fresh water and repeat the process to flush the boiler.

Do this regularly depending on how much you use it, the levers are pretty tolerant but the pump machines less so and scale will stop it working at it's best and can cause leaks and could eventually lead to element damage.

TIP:- Use your standard kettle as a gauge, if that is getting scaled so will your machine or use a small torch to peer into the neck of the lever machine boiler (not possible with the pump machines).

If you can still detect anything taste wise, use sodium bicarbonate after rinsing, see above (it has it's own cleaning effect and neutralises the acid and any taint in the machine).

I am trying out sulphamic acid but need to find a copper inhibitor -still looking - any ideas?

Click on this link for citric, acetic and sulphamic acids.

limescale micrograph