When do you water-break test for cleanliness?
Q. Our plant does chemical cleaning and passivation of various aerospace components and within these processes we do a Water Break Test to ensure the parts are clean. The question has arisen, as to when in the process is the WBT to be done. Some say after the rinse following the alkaline cleaner and some say after the final cold rinse at the end of the entire process.
Is there an expert out there who can give me a definitive answer or a definitive spec?Raymond Berry
aerospace - Jackson, Michigan, USA
A. Hi Raymond,
The water-break test is normally done after the rinse following the cleaning step. If your parts are not clean at this stage, then your passivation process may be adversely affected. You can perform the test after the final stage and you should still get a water-break free surface. But you won't know for sure whether the surface was perfectly clean following the cleaning step if you do the water-break test at the end of the line.George Gorecki
- Naperville, Illinois
A. Raymond, you have asked an interesting question. Having formulated and done trouble shooting on cleaning applications for over 20 years, I consider myself as somewhat of an expert in the field. My answer to your question would be the parts should be water break free at the end of the process. I would even go a step further and say the water break test should be done with pure water, not water from the process. The reason for this is the water from the process could potentially be contaminated with surfactants from the cleaning operation. These materials reduce the surface tension of the water and may allow the water to wet out and sheet on surfaces which are contaminated. It is very likely the rinse after the cleaning stage is contaminated with surfactants from the cleaning stage so it will general wet out better than the other rinse stages.Roy Nuss
Trevose, Pennsylvania, USA
A. Dear Raymond,
The water-break test is normally done after the rinse following the cleaning step to [indicate the need for] re-cleaning it if it still has any organic soils; but your rinse water must be very clear and not have any chemical contamination from the chemical cleaner tanks (surfactant). If you are not sure from that, you can take a sample out the line and check it by clear water.Aly Gomaa
- Cairo, Egypt
A. In my opinion both are valid answers. Only that Mr. Gorecki's emphasized the theoretical point of view while Mr. Nuss got into the practical aspects of the everyday situation. Conclusion: whether you do the WBFT in between or at the end, be sure to use the proper water. Indeed, when there is doubt about the test and if the base material tolerates it, a brief rinse with week acid water will neutralise alkalies and help wipe off surfactants, revealing hindered contaminants.Guillermo Marrufo
Monterrey, NL, Mexico
Q. What are the expected results of the water break test after the next step in the process, i.e., passivation? I ask this because I use technology that allows me to paint or plate without the use of cleaning chemicals, phosphates or acid activation, but cannot pass the water break test after cleaning. I clean using distilled water with no chemicals and parts pass all clean tests but not water break -- how do I explain this?Walter Johnson
- Machesney Park, Illinois, USA
A. I don't believe that a waterbreak-free surface is required for most painting, so maybe you don't really have much of a problem on that one.
But for many decades a waterbreak-free surface has been considered a necessity for most electroplating; so that one is pretty hard to get around. And I have to question your contention that the parts are fully clean if they fail what is, after all, a test designed to prove that parts are clean rather than just looking clean. But maybe the test isn't really fair after all. Have you plated parts and then tried some extreme baking cycles to prove that they won't blister? Have you tried bending electroplated coupons over a small diameter mandrel? Have you smashed brittle parts and looked for chips? Have you performed a "modified Ollard" adhesion test? If you can demonstrate perfect adhesion, that should do it.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
February 21, 2012 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. In our plant we are doing chemical washing for removing the oil and grease on the surface of casting. Our process is degreasing (I) 1 minute washing , degreasing (II ) 1.5 minutes washing, water rinsing (I) 1 minute washing, water rinsing (II) 1 minute washing, and Passivation 1 minute washing. I want to know whether water break test done before passivation or after passivation which one will give perfect result for ensuring surface cleaning.Jagadeesh
- Chennai, India
April 28, 2013
Q. How do I perform a water break test and what are the results to look for?Allan Mcguire
self interest - Cleveland, Ohio, USA
A. Hi Allan. It is difficult to answer abstract questions. You haven't yet told us who told you to perform it, or why, whether you are doing it to plated parts, whether the parts are rack plated (or barrel plated such that you can't see whether there is a waterbreak or not), whether you must certify it or you are just wanting to use the test as an in-house aid, etc.
But I'll start with the general proposition, then maybe you can refine the question . . .
Electroplating is a process where one layer of metal is "grown" upon another metal, and for this to be done correctly and with full adhesion requires that the part be free of soils and oxide layers, so the metal grows on metal. Your cleaning process removes the soils, and one way to know that the soils have been removed is to look for any "beading" on the surface of the parts when they are lifted out of the tanks. If the part is free of organic soils, water will form a "sheet" on it, rather than wet and dry areas. Water should not "break" and leave any dry spot on the parts until it actually evaporates.
The previous discussion about when to look for this waterbreak largely has to do with the fact that cleaning solutions have surfactants (surface tension reducers) that can tend to "mask" the waterbreak. So, in production, the plater will not necessarily trust what he sees as the part leaves the cleaning tank, but what he sees when the part leaves the rinse tank after the acid activation dip.
But in addition to this "in process" check, it is also possible to pull parts out of the line in mid process and perform more exacting water-break tests. There are standard waterbreak tests including ASTM F22 [link by ed. to spec at TechStreet]. Good luck.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Cad plated parts are failing waterbreak test preparatory to primingApril 26, 2017
We try to clean the cad plated parts with acetone or MEK before application of primer but test for waterbreak-free fails, why?Houman zarkesh
- Canada, montreal