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Soak Cleaner / Degreaser: Alkalinity test & oil content


Q. Dear sir,
We are using degreasing (NaOH based) concentration 15%, pH 2-3, specific gravity 1.10- 1.15. We want to know how to titrate the concentration of this solution.

shift supervisor - ABU DHABI,UAE
July 26, 2022

A. Hi, Mohd Tariq.
The pH of your alkaline cleaner is certainly not 2-3 :-)

But we appended your question to a thread which explains how to titrate the concentration (and, as importantly or more so, how to analyze the oil content). If anything is unclear, please come back with specific questions.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Closely related historical Q&A's, oldest first:

(to provide context, hopefully helping readers more quickly understand the Q&A's)

Most electroplating processes, and many other metal finishing operations, must start with an alkaline "soak cleaning" and/or "electrocleaning" step to remove soil and oil from the components.

These solutions do less reliable cleaning as they become loaded with those soils and oils, and they may become exhausted over time. So titrations to determine alkalinity and oil content are fairly routine analyses which must be performed.

Q. Simplest way to detect oil contents quantity in chemical rinsing (degreasing) prior to phosphating? Kindly help me out to resolve that problem.

Furqan Butt
- Karachi, Sindh, Pakistan


A. Dear Sir:

The best way is to extract the oil with some solvent like Methylene Chloride. Then dry the solvent and weigh the oil residue.

yehuda blau
Yehuda Blau
YB Plating Engineering and Quality - Haifa Israel

August 16, 2018

Q. How to dry the solvent and weigh the oil? Kindly help me with solutions.

deep janani
Yamuna Coaters - Rajkot, GUJARAT,INDIA

To minimize searching & thrashing, multiple threads were merged; please forgive repetition, chronology errors, or disrespect of other responses (they probably weren't there) :-)


Q. My question regards testing alkaline soak cleaners for the ratio of free to total alkalinity. We have an alkaline soak cleaner which is titrated on a regular basis for cleaner concentration, with subsequent cleaner additions made based on the analysis results. We notice a reduction in cleaner performance over time. It has been suggested to us that measuring the free/total alkalinity ratio would give us more information as to the effectiveness of the cleaner, and allow us to decide when the cleaner should be dumped vs. further additions. I would like recommendations of a specific method to measure the ratio, as well as any insight as to interpreting test results. Thanks for your help!

Thomas Kemp
Metal Finishing employee - Erie, Pennsylvania, USA


A. I think you need to check the oil content and the sludge at the bottom of the tank. Usually 3000-3500 ppm of oil if found the cleaner then the bath should be discarded. Do regular filtration and oil skimming depending on how many hours you run your plant.

I hope this helps you.

Best Regards,

Anurag Kanaujia
- New Delhi, India


Q. I am also looking for that test. We have a skimmer on our tank but I do feel that a total alkalinity test is a very good idea, especially on our passivation system where clean parts are so very important.
Can anyone help?


Micheline Forth
metal works - Savannah, Georgia, USA


A. This is the basic test we sometimes use;

10 mls of cleaner to 100 mls of DI water.

Add 4-5 drops of phenolthalien.

Titrate with 1N NaOH ^ HCl until clear. Record amount=mls#1 (this is normally the same titration as given by the supply house.)

Add 4-5 drops of Methyl Orange.

Continue titration until color change. Record amount =mLs#2.

(mLs#1 X 133)/(mLs#2)=Cleaner Activity

-- a Cleaner Activity below 75 probably needs changed or bumped. When the cleaner is old you will get a good number when you titrate using phenol but with methyl orange it will "pop" you on the activity rating.

Hope this helps.

J. Ott
plating shop - Harrisburg, Pennsylvania


? J Ott, take a look at your procedure. It is an alkaline bath, so you can not titrate it with NaOH. You probably meant 1N HCl.

James Watts
- Navarre, Florida


thumbs up sign Yup, that's what I meant sorry for the typo.

J. Ott
Plating Shop - Hbg, Pennsylvania


A. I think total or free alkalinity will help to some extent, but for finding effectiveness of degreasing chemicals to check oil content of the cleaner bath will help more.

Milind Padwal
- Pune, India


Q. I am interested in this, I am familiar with acid titration for determining cleaner concentration, but how does one go about analysing the oil content of the cleaner?

John Reid
- Brisbane, Qld, Australia


A. The basic titration test for Alkalinity is as follows:

- 10 mls of cleaner bath solution.
- Add 4-5 drops of phenolthalien.
- Titrate with N/10 HCl until clear. The reading you get thru the burette is the total alkalinity.

To check Oil content in the Degreasing Solution following is the test:

- 50 ml of bath solution is heated with 50% H2SO4 in 100 ml measuring flask or cylinder in a water bath. The separated out oil layer volume is noted.
- % of Oil Content = Volume of Oil Layer x 2
- Oil content is permissible up to 4-5%; above this level the bath needs to be discarded. The experiment is carried out once in two weeks or depending upon the production load.


- New Delhi, India

July 22, 2010

Q. Thanks for all people that have been contribute to this topic.Actually by now, I try to find out the simple method to analyse oil content of degreaser solution. I have tried to analyse oil content by extraction solvent - water - oil. I use n-hexane. But, the result is disappointing (not valid).

Ok, by the way I just tried this method above (using H2SO4) but, after boiling, the solution became a jelly, not separated oil-water. I will very much thank you if somebody can explain to me why this is happen?

Thank you

Made Antana
chemical supplier - Jakarta, Indonesia

January 19, 2012

A. Perform the Free Alkalinity and Total Alkalinity titrations as instructed in the other posts.
The total to free ratio starts out at 1.7-2.0:1.0.
Once this is approaching double the initial ratio of 3.4-4.0:1.0, you should consider dumping the bath. If a total dump is not an option, then drain off at least 1/3 of the bath and refill, add chemical.
You can make your cleaner bath last longer and save money, if you take the overflow from the following rinse and add to the cleaner tank as it needs water.
For the acid-split, follow the instructions in the other posts, except do not heat the cleaner. It will heat up on its own (exothermic) when you add the 50 mls of acid to the 50 mls of cleaner. As the oil that floats to the top of the cylinder approaches 3 mls, consider dumping the bath.

David Yopp
Sr. Chemical Sales Consultant - Louisville, Kentucky, USA

May 30, 2013

Q. I have a little confusion in the method of measuring oil contents. Please guide whether 50% of sulfuric acid means 50 ml or 50 % its strength? The exact quantity for 50 ml degreaser bath sample?



asim altaf
- lahore, Pakistan

May , 2013

A. Hi Asim. I believe it's both. The procedure requires 50 ml of 50% strength H2SO4.


Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

September 23, 2018

Q. Would you like to explain the steps how to determine oil content in alkaline degreaser and its range value as standard to makeup new bath? Please help from this forum. Thanks.

Anis anis
Chemical supply - Jakarta, Indonesia

September 2018

A. Hi Anis. We added your question to a thread where the test method is explained. Anurag suggests that at about 4-5% oil content the solution should be discarded, and David has suggested about 3%.

If anything remains unclear after reviewing this page, please re-post in terms of what you don't understand. Thanks.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

September 26, 2018

Q. Thanks Mr.Mooney. I see. How about with extraction methods use n-hexane as solvent in separator funnel and get the result of oil content in ppm value. Any information/explain about step by step to determine oil content with that methods (extraction methods)? And I saw from this forum that standard of oil content in degreaser about 3000 - 5000 ppm.

Anis anis [returning]
Chemical supply - Jakarta, Indonesia

sidebar January 2, 2019

Q. I am interested in this topic, and I want to know how to detect oil content if the solution bath is acid?
Can anyone help me?

Renaldi Morgan
- Jakarta, Indonesia

January 2019

A. Hi Renaldi. Acid isn't often used as a degreaser because it generally doesn't work. Are you talking about a degreasing bath in a electroplating line or something else? What is supposed to be in this acid bath and what is not supposed to be? I'm confident that titration reagents and indicators are going to depend upon what acids are involved. Plus, if there are organics in the composition of the bath, they probably need to be considered. Please introduce yourself and your situation. Thanks!


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Galvanizing Degreaser Testing

November 8, 2019

Q. It's common to use a degreaser in the pretreatment of hot dip galvanizing. Many plants use an alkaline one, mainly NaOH with some surfactants and chelates mixed in an aqueous solution.
Over time the liquor gets loaded with dirt (filterable or able to be settled out) and oils from the emulsion of oil and NaOH.
Do you know of any test to determine when this brew should be changed out? In the past we've cleaned a tank by decanting the settled liquor, dig out the dirt, pump back the decanted clean liquid and make up the difference with new brew. But is there a stage when such a practice isn't possible any more? And if so how do you test for it? We could measure the oil content, but what value indicates "spent"?

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK
crithwood logo

November 11, 2019

A. Hi Geoff,

I can't think of a specific test to determine whether a solution is "spent". I guess you do a waterbreak test after the alkaline cleaning/degreasing operation. I would suggest that, after you have "reconditioned" your solution, if you cannot get a consistent pass for the waterbreak test, the solution is now "spent".

Brian Terry
Aerospace - Yeovil, Somerset, UK

Determination of percent Oil in soak/electro-cleaner

January 3, 2020

Q. Hello everyone. My name is Chris Pease. I work as Senior Lab Technician and Technical Operations Assistant at AMZ Manufacturing in York PA. USA.

Some background on me: My previous job was as an analytical chemist for a lab in Harrisburg PA. Prior to that I was chemist and laboratory manager for a Caterpillar Dealer oil lab in Harrisburg PA. I originally was a chemist for an electroplating shop in Harrisburg PA right out of college.

I've got a situation here that I am asking help with, as I could not find a published method.

I am hoping someone out there has a method to determine percent oil in a soak and electro-cleaner.

We use a brown multipurpose cleaner that is a combination soak and electro-cleaner. We have belt oil skimmers on our tanks. The skimmers are very efficient and remove "liquid" from the cleaner baths which is questionable whether or not is 100% oil. I am afraid that we may be "skimming" off some of the cleaner chemistry as well as oil.

Because the cleaner is brown in color, it is difficult to determine whether or not the liquid that we are removing is oil or cleaner chemistry.

Most of our oily parts are degreased with N-Propyl Bromide before even being submersed in the cleaner bath, so I find it difficult to believe that the quantity of liquid we are removing from the cleaner baths is all oil.

I found a similar post in this forum that had a method for determining oil in degreaser, but I'm not certain that would work for a cleaner as the matrices are quite different.

Another way would be to have the waste that we are removing from the cleaner analyzed, but I want a method that we can use in-house routinely to monitor the percent oil in our cleaners.

Any help would be greatly appreciated!

Chris Pease
- York, Pennsylvania, USA

January 6, 2020

A. Hi Chris,

First problem you have is that alkaline cleaner/degreasers are designed to emulsify the oil, so they do not simply sit on the top of the tank, otherwise you'd be re-contaminating your parts as they leave the tank.

If you are using NPB prior to alkaline cleaning, I can't imagine there is very much oil left on the parts at all, assuming the degreaser is set up correctly.

A suggestion, with no promise that it will work...

Take a sample of the process bath at the surface and place in a clear beaker/container. Leave it sit undisturbed for 24 hours and look to see if you have any oil separation. If there is free oil it will sit on top of the bulk fluid as a separate layer.

Best of luck.

Brian Terry
Aerospace - Yeovil, Somerset, UK

January 7, 2020

Q. Thanks for your reply Brian.

The problem is that when the cleaners are in use and fully heated to operating temperature (190 degrees F), we can sometimes see what looks like an oil slick floating on top of the bath.

The skimmers catch this substance and we send it out as a waste product thinking that we have captured oil. We are now thinking that what we see and capture may be part of the cleaner chemistry itself.

The combination soak/electrocleaner is dark brown in color which makes it difficult to differentiate what exactly the substance is.

I am looking for an analytical method to determine if it is oil or not.

I'm not sure if the method listed previously in this thread for a degreaser, using sulfuric acid, would work the same for an alkaline cleaner.

I do remember some method back in the early 80's that we used to use with sulfuric acid for oil determination in an alkaline cleaner, but I do not remember the specifics.

I'll try your suggestion and see what I get, but if it is indeed cleaner chemistry that we are seeing "oil out" (no pun intended), I don't know that I'll gain any knowledge of what exactly is happening.

Thanks for the help.

Chris Pease [returning]
- York, Pennsylvania, USA

April 16, 2020

A. We use a very simple test to determine if the layer on a surface is oil or surfactant.
Take some of the layer in a flask, add some water and mix it well.
Surfactant will be soluble in water, oil not.

Daisy De Koning
Mavom Chemie bv - Zele, Belgium

May 4, 2020

thumbs up sign Thank you Daisy. That makes a lot of sense and is a very simple test to perform.

Chris Pease [returning]
Electroplating - York Pennsylvania USA

May 7, 2020

A. Hi, Chris,
1. The purpose of aqueous degreaser is to remove the oil from the part surface. If your parts are "water break free" after cleaner/degreaser, your solution works well.
2. Generally speaking, there are two groups of aqueous cleaners/degreasers - emulsion cleaners and alkaline cleaners. Emulsion cleaners convert the oil to emulsion and you will not see the oil film on the surface of the solution until it become saturated and should be replaced. No skimmers used in these solutions because no oil film is expected. These solutions are mild to slight alkaline and could be used to clean aluminium parts.
Alkaline cleaners are much more alkaline and will dissolve aluminium. They are formulated to "strip" the oil from the part surface and not to emulsify it. In these solutions you will see the oil film on the surface and use of skimmers is necessary.
3. The following method can be used to determine the oil content in the emulsion cleaner:
a) Fill the Cassia flask to the 100 ml mark with the cleaner bath to be tested.
b) Add 2 g of sodium chloride and swirl to dissolve.
c) Slowly and carefully (while swirling) add the concentrated hydrochloric acid to the 110 ml mark. Allow to stand for about 5 minutes.
d) Mix by inverting 3 times. Vent after each up-ending. Always point the flask away from the face.
e) Allow the mixture to stand undisturbed for 2-3 hours and read percent of oil.
Explanation: The purpose of sodium chloride and HCl addition is to break the emulsion and to free the oil.
We used this method many years ago, but finally decided that control by "water break test" is much better and practical.

Good luck!

Alex Sirota
- Lod, Israel

May 9, 2020

A. It is quite possible that you are trying to solve the wrong problem.
What looks like oil floating on an alkaline cleaner is frequently caused by excess detergent separating out. This is known as "Salting Out".
The root cause is often over-enthusiastic addition of cleaning salts on the premise that more is better and will improve cleaning. It doesn't.
Easy to test. Shake a sample of "oil" with a large excess of plain water. If it dissolves, it is not oil.
The treatment is simple. Dilute the cleaner to the manufacturer's recommended concentration and reduce the additions. You will save money and probably have no need for a scimmer which is just throwing away expensive detergent.

geoff smith
Geoff Smith
Hampshire, England

May 11, 2020

thumbs up sign Thank you Alex and Geoff for your most valuable input.

The product we are using is called Enprep 576E. It is a MacDermid/Enthone product.

The TDS states that is is a non-cyanide, phosphate free cleaner that is effective in removing rust, oils, silicated drawing compounds and lubricants. It uses a blend of deflocculants in addition to alkalies and detergents.

I think what we are seeing, AND CAPTURING, with our oil skimmers is not 100% oil. I feel that part of the cleaner chemistry is being captured by the skimmers.

The product is dark brown in color which makes it very difficult to tell what is floating on the surface.

Our lab technician performs a titration on the cleaner baths once a week. Additions are based on titration results. We keep the concentration in the middle of the TDS recommended range, so hopefully there is no cleaner addition overload.

Quality technical support is very difficult to get from the chemical suppliers and manufacturers these days.

Chris Pease [returning]
Electroplating - York Pennsylvania USA

<- Ed. note: No abstract
    questions please!
    Please tell us YOUR
    situation.   What? Huh?

September 1, 2021

Q. Hi,
Can you please tell me the titration steps?

maryam torabi

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