Methods to Determining Cleanliness in Parts Washing

In many industries, parts need to be cleaned thoroughly before/after being manufactured, during a production process or before being used to process a new batch of material. Automatic parts washers are often used to insure that parts are cleaned precisely. But how can you be sure that your parts are really clean? What are the methods to determine cleanliness? The following are just a few of the methods used to assess if a part is actually clean:

Water-Break Test:
Water will sheet off the part rather than bead

• Take a cleaned and dried part and set it in a vertical position. 
• Use a spray bottle containing distilled water. 
• Spray the part two to three times from at least 6" away. 
• If the part is clean and free of oily residue, the water spray should sheet off. 
• If some oily residue remains, the water will tend to bead on the part 

UV Black Light:
Can you see fluorescence on the parts when viewed using a black light?

• Take the cleaned and dried part and the black light into a dark area. 
• In the dark area, shine the black light onto the part. 
• If the part is free of soils, it should not highlight any fluorescence 
• If some soil remains, you should see some florescence where the soil is present. 
• You should check a dirty part for florescence to ensure that the soil emits a florescence when viewed under a black light. 

Clean-wipe test:
Will a white cloth remain white after being rubbed on the cleaned part?

• Take the cleaned and dried part and wipe it with a portion of a clean, white, lint-free cloth. 
• If the cloth remains clean, the part is sufficiently clean. 
• If the cloth becomes soiled or discolored, the part still contains soil residue. 

Gravimetric testing:
Will tell how much contaminate is left on the part

• Involves filtering a contaminated sample through a control filter and a sample filter. 
• Place two pre-weighed filters, one on top of the other in a single filter holder. 
• Sample contaminants will be retained entirely by the top test filter. 
• Both filters are subjected to identical alterations in tare weight as a result of moisture. 
• Any change in weight of the bottom ("control") filter is then applied as a correction to the weight of contaminant. 
• Results accurate to 0.1 mg are routinely attained using this method. 

Better Engineering uses these methods and more to assess and insure the proper cleanliness of parts. BE has a full engineering lab and machine demonstration center to test clean your parts according to your application. For a complimentary parts cleaning consultation, contact Better Engineering at 1-800-229-3380 ext. 310 or visit us at www.betterengineering.com.

Better Engineering Mfg., Inc. • T: 800-229-3380  F: 410-931-0053 • info@betterengineering.com • www.betterengineering.com Industrial Parts Washers