Products Finishing Online


Zones Suppliers Products Articles Clinics Subscribe Contact Us

Zone Home | Previous Page

Aqueous Cleaning

Parts Cleaning articles from Products Finishing are selected and categorized by application for quick reference:

Pitting of 7075 and 2024 Alloys   10/01/08
I would like to know more about the pitting problems in 7075 and 2024 aluminum alloys. We currently make anodized parts from both alloys and on occasion we see pitting after cleaning. I have recommended RO water in the tanks and DI water in the seal tanks.

CLEANING COPPER   08/01/08
I have a question about the cleaning of copper. The copper has become yellowish, so I need to remove the stain but cannot use anything corrosive thath may have an effect on the material. What cleaning material or process I should use?

Bromine Solvent   06/01/08
I recently heard from a customer of ours that some electronics firms are forbidding the use of bromine-based solvents in cleaning their components. No specific reason was given. Have you or your cleaning experts heard of such a recent ban? I would appreciate any information you have.

UV Clear Coat Over Metal   06/01/08
Our company is coating a high polished metal with a UV clear coat. Our precleaning process includes hot alkaline cleaner at 150°F, 80-psi impingement spray, city water rinse and DI water final rinse at 100°F followed by a 120° air blow off. The parts are then sprayed with an electrostatically charged material in a bell. Our question is whether rust sometimes occurs under the UV coating. Can you explain why some may rust quicker than others in a non-humid environment when routine maintenance is performed on all tanks and not all parts rust?

Painting of Stainless Steel Pipe   04/01/08
Mr. Peterson, we need a procedure for painting of Type 304 stainless steel pipe. The pipe was installed on-site without painting. In operation, pitting has been observed, so we have to paint the pipes. Unfortunately, blasting is impossible so we must use a chemical method for preparing the surface. Can you recommend a procedure for preparing and painting the surface.?

Iron Phosphate Start-Up   12/01/07
I read an article you wrote on PFONLINE. I was hoping you could give me the short answer or a reference for what the wastewater issues may be with iron phosphating. I understand it is safe, but can't find specific information about it and would like an expert's point of view. What do you think about iron phosphatizing and wastewater issues? Any information you can offer would be greatly appreciated.

Rinse Tank Water PH   12/01/07
Some of our customer specifications call for rinsing anodized, chromate-selaed parts in cold (ambient) water, while others call for a hot water rinse. What effect, if any, will raising the temperature of RO water in a post-anodize, post-chromate rinse tank from ambient to 130°F have on the water's pH value? Is there a way to rinse in hot RO water, max 130°F, and still be able to maintain a pH level on the part between 5.5 and 8.0 or the water in the rinse tank?

Sporadic Rust   12/01/07
We have not experienced a rust issue except for the seasonal heat and humidity but now have sporadic rusted parts all year round. Any thoughts?

Black Grease in Pickling Line   10/01/07
I operate a stainless steel pickling line. I very rarely get a grease-like substance clinging to the surfaces of parts after I remove them from the pickling bath. The parts are washed down with running hot water before processing. When they come out, it looks as if some black grease has attached to the parts. This only happens maybe once a month. I suspect that the stamping house is using a non-water-based stamping lubricant. We can have baskets full of parts sitting right next to the affected parts and the other ones will have no grease on them. Any help would be appreciated.

Rust on 17-4ph   08/01/07
I have parts that are made of 17-4PH stainless steel per AMS 5643, approximately ½ inch diameter by 1 inch long. They're rusting when our customer uses them, but products we have in our inventory from the same lot show no signs of rust. We machine the parts in-house using carbide tooling and then send them to a heat treater and thermal treater-H1025 per AMS 6875. Then they're sent out for bead blasting and are passivated per ASTM A 967. Could the customer's rust be the thermal treating or just poor passivation, and to what extent can these parts be expected to rust if they are processed correctly but subjected to extreme conditions?

Zinc Removal   08/01/07
I own a powder coating shop and process large amounts of both steel and aluminum. I have a three-stage wash with a multi-metal iron phosphate single-stage cleaner. I now have a customer who wants to bring in galvanized panels from China, and I'm concerned about the zinc going into my waste stream. Where could I find a solubility versus pH chart for zinc?

Cleanliness Test   06/01/07
The application I have is a cleanliness requirement for a metal washer. Please let me know if you know of a test kit available to perform this type of analysis.

Hazy Parts   06/01/07
We have a turntable washer with two stages: cleaner coater and rinse with tap water. The parts to be cleaned and powder coated are CRS sheetmetal boxes, enclosures, etc. The cleaner we used for four years worked great until recently. After the initial few days of the new bath, the parts start to develop a haze when cleaned. When it's been long enough it's so thick you can't see the metal in areas where the sprays don't directly hit. Every time I titrate and add the chemical, it disappears for a short time.

Calculating Energy Savings   04/01/07
I want to calculate the energy savings associated with reducing washer bath temperature.

Clingier Can Be Better   04/01/07
Gel cleaners extend dwell time, provide better cleaning

FRP Parts Washer   04/01/07
I am considering the use of a 5 stage part washer constructed from FRP (Fiber Reinforced Plastic). Do you or know anyone who has any experience with a washer constructed from this material? It is intended to wash mild steel sheet metal parts.

Cleaning Copper   02/01/07
I have a copper sink. Can you tell me if there is a remedy to coat the surface to alleviate the spots/tarnish....A friend said she uses lemon oil to wipe down her stainless steel sink.

Removing Rust, Mill Scale And Oils In One Step   02/01/07
We have a small job shop that powder coats. We do parts of varying sizes all the way up to 20 ft in length, made of steel or aluminum, occasional magnesium. The parts we receive, as stated before, are constantly different sizes and shape and some of it is made of HRS steel and has rust and corrosion on it, as well as oil. I always see the typical pretreatment stages to be a cleaner, rinse, phosphate, rinse, sealer, rinse or not. Nowhere do I see anything to deal with the rust and mill scale from the HRS steel. Is there a product that removes the rust, mill scale and oils in one step? Or are there more steps required, I can honestly say most everything I ever read about seems like a perfect world where the only thing the steel has on it is oils. This is not the case in my business. We have a manual spray washing system that we use due to our varied parts, but I can absolutely see the need for a dip tank being a useful tool as well for the smaller parts.

Smut On Titanium Parts   02/01/07
I use a Nitric/HF bath to etch titanium. Afterwards I desmut in 45% by volume nitric acid solution. Recently I have been noticing smut on parts.

Thermal Cleaning   02/01/07
We currently use a phosphate/rinse/non-chrome seal on light gage sheet metal parts. Someone has suggested we consider thermal cleaning instead of chemical cleaning as I'm getting our three-stage wash line quoted for replacement next year.

Removing Oxide Coating From Titanium   12/01/06
I want to find how would you remove the bluish color from the surface of titanium products?

Pretreatment of Multiple Substrates   10/01/06
We are currently coating various substrates for aerospace products with various coatings. We are using a Mil-T-81772 thinner via a wipe method to achieve pretreatment for coating. Our coatings are Chromate primers, TT-E-489 enamel, Epoxy primer and Mil-C-22750 Epoxy topcoat. Substrates are SS 300 series steel, alodined aluminum, anodized aluminum, titanium and magnesium. We are experiencing problems passing dry and wet tape tests. And I have been tasked to get us up to a NADCAP audit ready status. Is there any one method and chemical/solvent that could be used to clean all these situations?

Alodine   08/01/06
We use alodine on 5053 aluminum and use a water based coating. We want to change to powder but we are also having to meet the RoHS requirement that does not allow hexavalent chrome in the alodine. Have you found or know of an alternative to the Alodine that would give good adhesion and good Florida exposure.

June Issue   08/01/06
I am a loyal reader of PRODUCTS FINISHING and just finished reading the June issue. You are always very thorough and descriptive. I observed your response to E.P. regarding the phosphate cleaning systems and have some other suggestions...

Pretreatment   08/01/06
I am setting up a new Batch operation and wanted to know which pretreatment to go with. A 3 stage dipping system, or is a 3 stage hot pressure cleaning solution wash, Clear Rinse and sealant? Will the Iron railings benefit from a 3 minute dipping more than a power wash manually?

Passivate Using Different Materials   04/01/06
Can I passivate assembled parts with two different materials? One is 304 stainless steel tube and the other is 303 stainless steel solid. I am using epoxy glue made by 3M #2214 regular. I want to know if the acid will create problems to the glue or harm the parts.

Passivating Brass Shell Cases after Pickling/Polishing   10/01/05
I am running a mass finishing process that requires an aqueous passivation of the brass as a final process to help prevent corrosion. Can you recommend a chemical additive we can use with our rinse water?

Aqueous Cleaning Market   08/01/05
I am trying to find out the size of the aqueous cleaning market for a presentation. Do you know an approximate figure?

Precleaning for Laser   01/31/05
We produce some small parts of CDA 798-2 Nickel-Silver that require laser stenciling. The stenciling is done by an outside vendor. The customer is complaining of dark spots on the surface next to the marking. The laser people said that it would not be from the laser operation but from the residue on the surface prior to stenciling. They said it could be a film or even dust that gets heated up by the laser. What would be the recommended method of precleaning the parts?

Cleaning Copper   11/19/04
Two problems. First one deals with the fact that we cut copper blocks that measure 3x3x3. Our customer wants us to clean the soluble oil and possibly drawing fluids. We are a machine shop with no water treatment equipment. The parts must be clean enough to braze. Second problem: Is the citric acid passivate more safe than the nitric acid? I would like to do small parts in our shop. Can you tell me what the procedure would be?

Cleaning Method   11/19/04
I had a local metal fabricator cut a shape out of a 7×10 ft ×1/2 inch thick out of cold roll steel to be used as a tabletop. I want to take the existing blackish-rust colored finish down to the silver metal color so I can use a blueing kit on the entire surface. Can you recommend a cleaning method, other than mechanical? Everyone keeps telling me to grind it down, but I really don't want to do that if I don't have to. I would rather use chemicals.

Cleaning Question   08/01/03
Our company is researching the ways to chemically clean the graphite part from the deposited aluminum oxide. Any suggestions?

The Lubricant Switch   06/01/03
I recently switched metalworking lubricants in my forming operation. I went from a regular oil to one that was recommended by a salesman from a different company. That salesman claimed that his recommended lubricant would be much easier to clean off the parts since it is diluted with water. The demonstrations he gave showed it to clean off some sample parts very easily, but now that we are in full production with their lubricant we have found it more difficult to remove and also noticed staining. We now have a new salesperson, and he has not helped us since the conversion. Can you let us know what has happened with this lubricant?

Stains on Plated Parts   06/01/02
I work for a plating company that deals with plastic plating. We have a problem with water stains on parts after they come out of our dryer. After going through the decorative chrome, the parts go through four rinse tanks. The last two are DI water, yet we still have some stains. Is there anything else that we can do to avoid these drip stains?

Cleaning Before Passivating   04/01/02
I need some advice. We have a new customer with 17-2 stainless parts requiring passivation. The parts have a heavy brown oxide on them as received. We need to remove this before the passivation treatment. What do you suggest to do this with?

Passivation of 440C Material   04/01/02
Can you explain what would cause 440C material to etch in a passivation bath of sodium dichromate/nitric operated at 120F?

Chemical Machining of Aluminum   02/01/02
We are a UK finishing equipment manufacturer and have an application where our client needs to chemically machine aluminum parts by masking and etching away selected areas with alkaline etchants. We know that this process is carried out extensively in the aircraft industry for forming wing skins, and we are sure that there are some companies in the U.S. that supply suitable proprietary processes for this application. We believe that many of these processes conform to MIL or Boeing specs. We would really appreciate any contacts that you can suggest who may be able to supply our client.

Pretreating Laser Cut Parts   01/01/02
Can you recommend a pretreatment cleaning process for laser cut parts? The laser cut edge leaves an oxide area that causes adhesion problems. Often the cured powder coating will chip off these edges when they come into contact with each other. We have a four-stage washer using alkaline cleaning and phosphatizing. Most (98%) of our parts are HRP&O steel, with the remaining 2% being CR and aluminum. We also have heard that if we cut with nitrogen on the laser it will reduce the oxidation of the material; however, nitrogen is also 60% more expensive than oxygen...

Alkalinity Loss in Cleaning Stage of Washer   12/01/01
We are experiencing significant drops in the alkalinity of our first stage cleaning bath in a seven-stage pretreatment line...

Graphite Cleaning   12/01/01
Our company produces aluminum extrusions for paint. During the extrusion process, the aluminum is carried over graphite blocks, with graphite contamination adhering to the aluminum surface...

Nozzle Selection   12/01/01
In your April 2001 column you were asked about phosphate system pressure. One area that you should take into concern when discussing operating pressure is the spray pattern that the nozzle is designed to produce...

Pretreatment Rinse Tanks   12/01/01
I have a five-stage dip process. The first tank is a cleaner (liquid acid); second tank is a rinse (city water); third tank is a chrome tank (chrome phosphate and fluoride); fourth tank is a rinse (city water); and fifth tank is a rinse (city water)...

Watertight Masking Device   12/01/01
I am working on an issue with a company regarding a pre-paint cleaning operation. We have certain areas of the axle assembly, which have complex surfaces, that allow cleaning solution to contaminate internally...

Cleaning Low Carbon Steel   10/01/01
I have constant velocity joint components from an automotive application that I believe to be a low carbon steel. In some areas they have a 58-62 HRc surface hardness with a 0.040-0.060-inch case depth up to 50 HRc. I wanted to clean them with a 20-30% phosphoric acid, 70-80% water solution warmed to 180F for 10-15 min in order to remove grease and rust. I have run this experiment and made a dimensional, hardness and surface finish comparison. Only the surface finish changed slightly. Are there other things to be concerned about such as hydrogen embrittlement?

Cleaning Magnesium   10/01/01
What is the recommended chemical cleaning process and composition prior to electroless nickel plating for magnesium?

Cleaning Rust from Cold-Rolled Steel   02/01/01
How can we clean the rust off of unpainted cold-rolled steel parts slated for electrocoating that underwent an atmospheric corrosion attack from an accidental release of muriatic acid vapors in our plant? This is a real-time nightmarish problem that I think other manufactures have faced. What are other chemicals besides muratic acid that need to be banned from our sheet metal fabricaion plant?

Powder Metal Parts Cleaning   02/01/01
I read Products Finishing, and I have come across a new opportunity for my heat treating company. We are being asked to carburize, oil quench, clean and temper a small part, 4.75 grams each. The part has a density of 7.0 ±0.05 grams/cu cm. The part is currently made and processed in Japan. While I am not aware of the environmental issues in Japan, I would think they are similar to our laws and the impact to cost of chlorinated solvents is what I am trying to avoid. Any advice on types of alternative cleaners or processes would be appreciated. I am not opposed to paying for consulting advice if you can refer someone who is knowledgeable.

Prepaint Treatments   12/01/00
We are currently plating zinc and yellow chromate for a customer. Our customer, because of shop soils and fingerprints, precleans all the zinc/yellow chromated parts we have plated prior to painting.

Technical Terms   12/01/00
We are in the process of upgrading our paint line. I was speaking with a chemical supplier about a three-stage washer. He used the terms "windage" and "drafting." I have never heard these expressions used in industry. Can you please tell me what he meant?

Anti-Tarnish Products   11/01/00
How do we prevent tarnish from forming on stamped copper lead frames? The lead frames are stamped out of oxygen-free copper and shipped to a molding company, which molds the stampings into a plastic part, which is then shipped to the assembling plant. The stamper swears parts are tarnish-free when shipped. The molder says parts come in tarnished and they have to sort them. The molder swears the parts are good when shipped. Incoming plant inspection says the parts come in tarnished and they have to sort them. The plant has to ultrasonically weld conductors to copper lead frames. How can the finger pointing be stopped? What are the proper ways to ship parts? Are there anti-tarnish products that could be placed inside the shipping carton boxes?

Fisheyes   11/01/00
We're having a problem with fisheyes and need some advice. We have a seven stage pretreatment, epoxy electrocoat and TGIC polyester powder topcoat. The fisheyes are obvious after electrocoat. We can see where the fisheyes will occur after pretreatment-there are bright silver spots, sometimes with a "comet" tail. EDS of the center of the fisheye shows aluminum and silicon, sometimes calcium. The defect does not happen on hot-rolled steel. The defect does not occur on vacuum degassed interstitial free hydrogen annealed cold-rolled steel. The defect does occur on commercial quality cold-rolled, draw quality aluminum killed cold-rolled, and INTEK nickel flash cold-rolled steel.

Pickling or Solubilizing?   11/01/00
I am in the business of cleaning metal stampings. Recently an automotive customer developed a problem of heat treating a carbon steel part and created a scale on the surface. Engineering decided to use a vibratory media process to remove the scale (expensive). They knew that "pickling" was an option to remove the scale but decided not to because of hydrogen embrittlement. I use a low concentration of inhibited HCl, which removes scale and oxide from parts every day. I've tried to convince them that I am not "pickling," simply solubilizing the surface contaminants (oxides) without going after the steel itself. Am I correct in my thinking? Do you have any research materials on hydrogen embrittlement to help clarify for me and the automotive gurus?

Plating Zinc over Heat Treating   11/01/00
I am not able to plate zinc over an area that has been heat treated. Any suggestions?

Vacuum Deposition of Selenium   11/01/00
We vacuum deposit selenium on 3003 and 6063 aluminum alloy drums for copy machines. The drums must be exceedingly clean. We have tried a number of cleaning methods to promote good coating adhesion. These include a non-silicated alkaline cleaner, various etch solutions, including potassium hydroxide, sodium hydroxide,hydrofluoric acid, followed by nitric acid, phosphoric acid and other desmutters. We have even used a sulfuric-chromic mixture to clean the parts and desmut in one step. This worked great and so does 50% nitric acid, but we have some safety concerns with these. What can you recommend that is both safe and will provide the "tooth" necessary for good adhesion of the selenium?

Plating on Aluminum   10/01/00
We plate aluminum (6061) parts with cyanide copper followed with an alkaline tin plate. We are using an acid etch to prepare the parts (10 min at 160F) prior to plating. We have a problem with blisters that appear a few days after the plating process is complete. What is causing this?

Tellurium Copper Problems   10/01/00
We are trying to plate silver over nickel on tellurium copper. We are having problems with peeling. When we plate beryllium copper parts we do not have this problem. Can you help us?

Preparation Before Ion Implantation   09/01/00
I would like to ask what preprocessing has to be done in order to prepare the steel surface before ion implantation of mould? What cleaning methods should be used? Thank you very much.

Cleaning Galvanized Steel   07/01/00
I need to clean galvanized steel mirror bases prior to painting. We can't remove the galvanization. Any suggestions?

Cleaning Molybdenum   07/01/00
Q. We have been trying to figure out how to clean molybdenum. Specifically, how to clean the brass deposits from EDM wire and how to clean off the oxide formed when it is exposed to water and air. Can you offer any advice or assistance?

Cleaning Very Small Parts   07/01/00
How are very small sheet metal parts cleaned with an aqueous solution? Because of surface tension, these parts stick to each other. Moreover, jigging them separately takes lot of man-hours. Please suggest a suitable mechanism to clean these parts.

Looking for a Product   07/01/00
I'm trying to find a spec sheet on products called Passa-Jell-107 and Passa-Jell-101. Not sure that that is the correct spelling. Is it used for cleaning and/or passivating metal?