Five Star’s blended acid cleaners are more effective than plain phosphoric acid because they offer a “one-two punch”.  The nitric acid component attacks the proteins while the phosphoric acid tames the nitric acid and conditions the water for a more effective cleaning.


What is nitric acid and how is it used?

  • Removes organic materials with inorganic materials. Nitric Acid nitrates the amino acids, as well as dissolving minerals, which then allows it to remove lay­ers of soil and not be stopped by ‘bio-layering’ which can occur when multiple brews are done without performing a cleaning regimen between each brew. A layering of soil types can also be a problem in direct fire kettles.
  • Is the most aggressive stone removing acid readily available to brewers
  • Reacts directly with the non-ferrous elements of stainless steel to actively cause the metal to passivate (or re-passivate). Other acids, by themselves, can clean the stainless steel of soils &/or rust to the point that the stainless steel can ‘heal’ itself, however, that process can require several days. By contrast, using a Nitric cleaning process, known as ‘pickling’ the stainless, is more effective and can be done in a single CIP session and subsequent air-drying.


How is Nitric Acid controlled in Five Star’s Acid Cleaners #5 and #6?

Straight Nitric Acid loves to fume, grabbing ahold of moisture in the air and ‘running’ as fast as possible. These traits are counteracted with phosphoric acid which is able to hold the Nitric acid in place. If you need a visual, the phosphoric is like a school bus on a mountain road with an eager teenager driving a sports car (nitric acid) behind it. If the school bus has its brakes get too hot (e.g. Acid #5 heated over 140° F) it will have to pull over to let them cool. At that point the teenager in the sports car can go down the mountain as fast as he wants without resistance. That is why it is important to keep Acid #5 below 140° F. The stronger the nitric acid solution, the lower the temperature should be.


What are the differences between Acid Cleaners #5 and #6?

  • Acid Cleaner #5 is the first choice for acid rinsing and washing as well as passivating and re-passivating.
  • Acid Cleaner #6 can be run up to 160° F as there is less nitric acid and more phosphoric acid in the ratio.
  • Acid Cleaner #6 is the preferred solution for stone removal and many other severe cleaning challenges because of a more robust detergency package.
  • While Acid Cleaner #6 does facilitate passivation, that is more an added benefit that a primary role of this formulation.
  • Acid Cleaner #6 was originally formulated for keg cleaning, relieving breweries from using a caustic in a two-step keg washer and preventing the buildup of stone in kegs over time.
  • Running Acid #6 at the higher temperature works better with the shorter cycle times of most keg washers.