If you’ve read any of our previous articles on parts cleaning, you’ll have seen references to pH testing. We’ve repeatedly encouraged you to check the pH of your cleaning solutions, but never really said anything about why. That’s what we’re talking about today.
What is pH?
pH is defined in the Merriam Webster Learners Dictionary as: “a number between 0 and 14 that indicates if a chemical is an acid or a base.” This is the simple definition, which serves our purposes just fine. The full definition of pH is:
noun : a measure of acidity and alkalinity of a solution that is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity and on which each unit of change represents a tenfold change in acidity or alkalinity and that is the negative logarithm of the effective hydrogen-ion concentration or hydrogen-ion activity in gram equivalents per liter of the solution; also : the condition represented by a pH number
pH in the Shop
So how does that affect you in the machine shop? Low pH values are considered acidic while high values are alkaline or basic. When cleaning parts, you want to achieve an alkaline mixture to prevent damage to the parts. We recommend you target a pH of 12. That said, if you find a slightly higher or lower pH cleans better for you, that’s fine. These recommendations are NOT carved in stone.
To reach your optimum cleaning solution, Chris Jensen from the Goodson Tech Service Department says you should start with clean water and add 1/4 pound of detergent to 1 gallon of water. Test your pH to confirm your levels. Run a cleaning cycle and if you need to adjust, do it a little at a time. You can go up to 1/2 pound of detergent per gallon of water, but any more than that and you’ll be over saturated and your cleaner will just create a sludge in the bottom of the tank.
Remember, a solution that’s too acidic may cause damage to the parts you’re cleaning and can cause you injury as well. Be sure when you’re working with any detergents to practice personal safety. Wear safety glasses, gloves and a chemical resistant apron.