The rainbow stain on stainless steel is what we call "heat tint." Prev. If cleaning stainless steel pans with soap and water doesn't do a thorough job, make a paste or slurry of baking soda and water. When your stainless steel has heat damage, it is possible to get some discoloration. This world famous chemical compound is known to remove heat-caused discoloration or “blue-ing” from chrome, stainless steel and precision metals which have been exposed to welding or other extremely high temperatures. Keywords: Color-Changing Water Bottle. Balance is achieved when heat treating and annealing stainless steel parts is precisely matched to their makeup and intended use. it will not restore the corrosion resistance. The cleaning fluid still remains on the surface of the stainless steel screw, so after a period of use, the cleaning fluid will react with it. discoloration of stainless steel due to heat. Weld Discoloration This article will identify acceptable levels of weld discoloration on mechanically polished and electropolished stainless steel surfaces and also show proven shop and field remediation practices to removes excessive heat tint. Topic Welding Industry / Technical Discussions / Stainless steel discoloration By apiguy Date 06-19-2002 16:16 Does anyone know where I can obtain a chart that would describe the heat tint discoloration of stainless steels. Additionally, we will show the effect of various oxygen levels and the impact heat tint has on corrosion This discoloration is sometimes known as “bluing.” Electrochemical weld cleaning is a process by which post-weld impurities such as rust, heat tints, and discoloration are removed from metal surfaces under the effect of mild electrolytic fluids and a weak electrical current. Failure to develop and maintain this passive film renders the surface active, or possessing corrosion resistance similar to conventional … Color: As picture. Weld cleaning | Wednesday, 14 October 2020. I seems low heat is the key as more turns it gray, but with the lower heat i fear poor penetration.. The color of the "stain" is a function of the layer thickness. OEM: Warmly Welcomed. 0 Comments Like: 0 Like: 0 While this technique may seem basic to some of you — cooking on high heat can burn food and give you less flexibility as you cook — stainless steel will discolor from constant high heat. Cleanse the discolored stainless steel with a terry cloth soaked in white vinegar. Usually this is a discoloration that cannot be removed. The three most important variables that determine stainless steel weld discoloration/oxidation are amperage, travel speed, and quality of shielding gas coverage. Balance is achieved when heat treating and annealing stainless steel parts is precisely matched to their makeup and intended use. This covers the surface with an iron-free chromium oxide layer and gives it the shine that stainless steel is famous for. Step 2. However, stainless can become discolored. During welding, the structure of the steel changes, and a chemical reaction (oxidation) occurs which separates the chromium from the metal base while also pushing it towards the outer layer. In order to imitate the discoloration of the screw, we will remove the phosphate film before the heat treatment. 1; 2; 3; Next. Usually, discoloration involving lighter (yellow) shades is much easier to remove since it forms under the influence of lower temperatures during welding. Sometimes i get a beautiful rainbow coloration of the welds and sometimes they are just gray and plain looking. Basically, when stainless steel is heated to high temperatures, the oxidized layer can thicken, causing a rainbow tint. The surface discoloration on stainless steel after grinding or welding is surface oxidation. Owning a stainless steel grill, it is important to be aware of some discoloration that can happen with heat exposure. It is just a matter of the argon shielding envelope leaving the hot metal before it has a chance to cool enough to not oxidize. First Prev 2 of 3 Go to page. Heat Tint Recognition Chart For Stainless Steel Welding Pictures 1a to 1 g provided by Norsok for the Norsok Standard M-601 Welding and Inspection of Piping (Edition 5 April 2008) (Annex B). Heat treaters are tasked with developing the right balance. sales@cougartron.com For stronger stains, a simple wipe with vinegar should do the trick. How to remove discoloration from heat? Supply Ability. Pictures below showing the blue/gold color. When chromium and air mix, a protective layer is formed on your pan. Though these marks appear as damage to the surface, they are simply a discoloration that can easily be removed. In order to imitate the discoloration of the screw, we will remove the phosphate film before the heat … The data of the water quenching medium can imitate the blackening of the surface of the stainless steel screw. With more chromium and oxygen, the outer layer of steel becomes thicker and loses its transparency. 2: Is there a way to restore the brightness? It's covered with a protective coating. 4. Fold up a paper towel and place it atop the discolored area on the cooktop. Stainless steel contains a small amount of chromium in it to help resist corrosion and rusting. Avoid scrubbing stainless steel with scouring pads or abrasive cleaners. However, the choice of method depends largely on the scope of the problem. This protective film develops when more than 10.5 percent of chromium is present in the alloy and when the gas or liquid environment the stainless steel is exposed to provides oxygen to its surface. Your stainless steel will be stain-free in no time! ONLY use to remove heat discoloration. While most stainless steels are resistant to oxidation at low temperatures, the various metal in the steel formulation (iron, chromium, molybdenum, etc.) iPhone X Stainless Steel Discoloration - Space Grey. Stainless steels are generally heat-treated based on the stainless steel type and reasons for carrying out the treatment. This is a very difficult material to heat treat without discoloration. 2. Oxidation of the root bead and adjacent HAZ during welding of stainless steels is commonly called heat-tint. Owning a stainless steel grill, it is important to be aware of some discoloration that can happen with heat exposure. How do you clean oxidized stainless steel? How to Clean Stainless Steel That Is Discolored From Heat Step 1. Heat stains can occur on stainless steel appliances for a variety of reasons. Most metals, including stainless steel, have an oxide layer at the surface. Does anyone have any idea how I can prevent heat-discolouration or blueing, when I've got them onto the bike? Fill the pan with water to cover the burnt food marks (1-3 inches depending on the depth of the pan) Pour ~¼ cup of baking soda into the pan, mix well, and bring mixture to a boil. Copyright @ Lizhan Hardware Co., Ltd. All Rights Reserved. … Stainless flatware is durable and long-lasting because it's basically made from iron alloys. Heat stains on stainless steel can result from multiple reasons. Stainless steel is a sturdy and reliable material commonly used in kitchen sinks, appliances and cookware. It may leave a few scratches, but that won't affect the heat conductivity of the pan. The reaction causes discoloration of the surface of the stainless steel screw. Figure 2 | 13-8Mo precipitation hardening stainless steel medical part discolored by air in the backfill gas. For instance, setting a hot pan on the stainless steel surface leaves a mark behind. Next Last. 2. Types of stainless steel . While this technique may seem basic to some of you — cooking on high heat can burn food and give you less flexibility as you cook — stainless steel will discolor from constant high heat. The electrochemical method is extremely effective in these cases since it successfully removes oxides from the surface and restores the anti-corrosive passive layer. The color combination depends largely on the amount of heat used during welding – darker colors (brown, blue, and purple) are usually formed at higher temperatures (> 370 °C or 698 °F). Heat discoloration could happen on flatware if it falls in the heating unit in your dishwasher or if you leave the flatware in a pot while on heat or directly on a hot stove. I was wondering about the discoloration of Stainless steel TIG welds . I have Motad stainless steel exhaust header pipes to put onto my 4PT, and a stainless steel tailpipe in the post. May 27, 2017 500 1,024 Netherlands. Surface discoloration and red rust after heat treatment of the phosphate film on the surface of the stainless steel screw. Heat Treat Discoloration Stainless steel parts are often heat treated to anneal (harden) the metal and relieve stress in the parts. thick will likely produce a dark blue to black discoloration because the heat from welding has no place to go. Fortunately, there are a number of quick and easy ways to clean your stainless steel appliances. The LaserBlast works extremely well on stainless steel. We all know that stainless steel screws are the origina […]. Heat tints appearing after stainless steel welding are a common occurrence in the industry. The fire in the mesh belt furnace area. Baking soda. Go. Stainless steel parts are often heat treated to anneal (harden) the metal and relieve stress in the parts. However, chemical pickling should definitely be avoided due to the harmful effects of nitric and hydrofluoric acids. The easiest way to reduce HI is to increase travel speed, assuming you have a voltage and amperage value that is producing the desired welder-friendly arc characteristics. The surface discoloration on stainless steel after grinding or welding is surface oxidation. Gently scrub the burnt food. The surface discoloration on stainless steel after grinding or welding is surface oxidation. Once the steel has become embrittled with sigma it is possible to reclaim it by heating the steel to a temperature above the sigma formation temperature range, however, this is not always practical. All of them indicate a change in color on the top layer of stainless steel – around the weld bead and within the HAZ (heat-affected zone). This type of flatware resists rust and corrosion. is a specially formulated product originally introduced to remove the "blue-ing" or heat-caused discoloration caused from chrome exhaust pipes on motorcycles or custom cars. Heat Treating Stainless Steel Discoloration. When cooking with stainless steel, we recommend that you use lower heat to cook your food. The characteristic color spectrum is just a visual manifestation of this process. The temperatures are too low for reducing gases, such as hydrogen to react, and inert gases such as argon have enough residual oxygen, a couple ppm, to discolor the product over the four hour hold at temperature.We can heat treat out parts in vacuum and if the furnace is tight enough we get bright product. Sampled by GE Appliances. This weld discoloration or “heat tint” should not be con-fused with the naturally occurring, transparent oxide film present on all stainless steel which is largely responsible for the alloys corrosion resistance in aggressive environments. You will most likely see this on the inside of the grill lid more than the outside since a grill is made for the heat. This discoloration is sometimes known as “bluing.” Another popular alloy of stainless steel, grade 316 SS is often used for applications that involve powerful corrosives, as its corrosion resistance generally exceeds that of grade 304 SS. 3. Basically, when stainless steel is heated to high temperatures, the oxidized layer can thicken, causing a rainbow tint. You will most likely see this on the inside of the grill lid more than the outside since a grill is made for the heat. Tel: +45 43 20 19 00, Introducing the New and Improved Cougartron Website, Cougartron Weld Cleaning Fluids – A Full Overview, Electrochemical marking and etching – easy and convenient way to mark/etch stainless steel and other types of metal surfaces. When cooking with stainless steel, we recommend that you use lower heat to cook your food. discoloration of stainless steel due to heat. Barry Feinman from Restore It Yourself, Inc. demonstrates how to remove the discoloration and heat scorching from the hood of Stainless steel BBQ grills. Over the years, industrial concerns have discovered that BlueAway is perfect for removing heat-caused discoloration on stainless steel welds. While stainless steel is famous for its resistance to oxidation and discoloration in most “normal” use cases, it’s important to note that no alloy is 100% impervious under all situations. Figure 1 | Severe discoloration of stainless steel parts and fixturing discolored by a water leak. Stainless steel's corrosion resistance is due to a thin, chromium-rich, transparent oxide film on the surface1. Types of stainless steel. During the heat treatment process, we need to raise the problem appropriately. Slow down. Vinegar helps rid the pan of blue streaks created when the pan is washed in a … Here we have a stainless steel pot that has burn surface stains. Body material: stainless steel 304. What Are Heat Tints and Corrosion Heat Tints . Stainless steel owes its corrosion resistance to its ready oxidation to form this protective film; however, stainless steel's exposure to an oxidizing environment at higher temperatures (or to a more highly oxidizing environment at a given temperature) will result in the formation of an oxide (heat tint) of increasing thickness, ranging in color from a light straw to a dark black. Mix the baking soda with a small amount of water to make a paste and clean with a damp cloth. You Will Need: Club soda; Soft cloth; Elbow grease; Steps to Remove the Heat Stain: Chromium carbides form in stainless steels along either side of a weld. Despite its name, even stainless steel can get stains. 0 Comments Like: 0 Like: 0 Usually this is a discoloration that cannot be removed. How to Remove Discoloration From Stainless Steel Step 1. Magic Heat Stainless Steel Discoloration Color-Changing Water Bottle. Heat tinting causes this naturally occurring oxide layer to become thicker which causes discoloration. A chromium-rich scale is formed, which is typically not very protective, and the stainless steel surface becomes chromium-depleted: these effects may impair the corrosion resistance of stainless steel welds. As explained in one of the previous articles, stainless steel is ‘stainless’ due to its chromium-rich composition and a passive outer layer that helps it to successfully fight corrosion. My heat treater says no, that the discoloration is visual and not mechanichal. The use of the pickling paste is widespread. Offer Dropshipping Service: Offer Dropshipping Service. Blue Away is available in small bottles with 60 ml or money-saving 1000 ml bottles. It gets its name because it resists stains. Applying the Chemical Solvent To The Lynx Gas Grill Control Panel. 2a 2b 2c 2d 2e 2f 12 ppm Oxygen level 60 - 70 ppm Oxygen level 70 - 90 ppm Oxygen level 200 ppm Oxygen unacceptable 250 ppm Oxygen unacceptable 500 ppm Oxygen unacceptable Tint Chart 24-05-2018 … If you are experiencing a specific challenge related to discoloration and stainless steel weld cleaning, give us a call or reach us through e-mail – we are always happy to help! In the process of stainless steel screw quenching, if the oil is too aging, it may also cause the screw to turn black. Barry Feinman from Restore It Yourself, Inc. demonstrates how to remove the discoloration and heat scorching from the hood of Stainless steel BBQ grills. Tips on Cleaning. Q. I'm new to the whole method of heat treating but I've got a question that I hope some of you have the answers to. If your amperage and travel speeds are within range of the stated upper limit with respect to the overall heat input, then you may want to take a closer look at your shielding gas quality and coverage. Temperature Tolerances for Grade 316 Stainless Steel. Heat can discolor stainless steel flatware, but generally pots are more susceptible to this type of discoloration. May 4, 2019 #26 Black PVD coating on cheap watches use to shrink when exposed to … The fire in the mesh belt furnace area. Under these conditions, the surface is passive, or resistant to corrosion. Thread starter JCCL; Start date Jul 24, 2018; Sort by reaction score; Forums. We need to check it from time to time during use. Logo Printing: Customer`s Logo. A discussion started in 2007 but continuing through 2019. Propane and butane will work on thinner metals just fine. Wednesday, 18 April 2018. Capacity: 350--500ml. We offer a variety of weld cleaning machines developed to successfully remove different types of weld tints and discoloration. Packing: 1pc/white/Color Box. Electrochemical Weld Cleaning – The Fastest and Safest Way to Clean Stainless Steel Welds. All of them indicate a change in color on the top layer of stainless steel – around the weld bead and within the HAZ (heat-affected zone). I'm using 20GA brushed or mirror finish so I need a solution that doesn't involve abrasives, etc. What are heat tints and how are they created. During the heat treatment process, we need to raise the problem appropriately. Intense heat will leave an orange and brown coloration that is in the stainless. As stated in an AK Steel data sheet for grade 316 stainless steel, the melting range of 316 SS is 2,500 ° F – 2,550 ° F (1,371 ° C – 1,399 ° C), roughly 50 to 100 degrees Fahrenheit lower than the melting point of grade 304 stainless. 1. In certain cases, the use of various methods is necessary but electrolytic cleaning in most situations is the most appropriate solution. What are the reasons for the discoloration of stainless steel screws, The main application of stainless steel hexagon screw. Let it cool for 30-45 minutes. A chromium-rich scale is formed, which is typically not very protective, and the stainless steel surface becomes chromium-depleted: these effects may impair the corrosion resistance of stainless steel … As you can see in the control panel here, the stainless steel has been badly discolored from the heat. Rub it thoroughly over the pan and let it sit for a few minutes. In order to imitate the discoloration of the screw, we will remove the phosphate film before the heat treatment. The rainbow stain on stainless steel is what we call "heat tint." My plant machines small cones for a valve assembly out of 17-4 PH Condition A Stainless Steel. Cleaning stainless steel pans with baking soda brings them back to the shine they had when you first purchased them. This oxidation causes the discoloration often seen on steel after heat treatments. iPhone . Pressure and heat as integral parts of the welding process are directly responsible for the formation of rust on stainless steel surfaces. Oxidation of stainless steel indicates that the metal temperature at the oxidized surface was in excess of 1000 °F. After the stainless steel screw is quenched, the water quenching medium remaining in the stainless steel screw will easily cause the rust imitation performance of the stainless steel screw to decrease and the phenomenon of blackening after a period of time. This is more common on grill hoods because over many years of high-heat grilling the stainless discolors from the build-up of heat inside the hood. Some customers have also asked before that stainless steel screws have changed color during use, red or black. Cook on low heat when using stainless steel cookware to prevent unsightly dark spots. iPhone. Second, the fact that the discoloration is more evident at the bottom of the load suggests the phenomenon is (gas exposure) time dependent, that is, the longer the parts take to cool through the critical range, the greater the chance for discoloration. The mechanical treatment of heat tint by stainless steel brushing [6.2.3(d)] simply burnishes the surface and does not remove the low chromium layer beneath, i.e. Stainless Steel Brightener Designed to remove heat discoloration (yellowing) from stainless steel surfaces. When chromium and air mix, a protective layer is formed on your pan. Possibly an acid I could immerse the part in? BlueAway is also great for cleaning molds, tools and dies. We all know that stainless steel screws are the original color, and in most cases there is no need for surface treatment, unless the customer requests it. I need to figure out how to remove the discoloration the heat from welding stainless steel produces. While most stainless steels are resistant to oxidation at low temperatures, the various metal in the steel formulation (iron, chromium, molybdenum, etc.) We explained all the important health & safety reasons here. Several methods are commonly used to remove discoloration on stainless steel after welding – electrochemical cleaning, chemical pickling, and mechanical grinding & brushing are just few of them. Weld cleaning | "We took some Phosphoric Acid (10% by volume) and used reverse current gotten from a few flashlight batteries wired together. Take a damp, abrasive sponge and gently clean the pan in a circular motion. Pour club soda onto a terry cloth and scrub the discolored area. At elevated temperature, the metal comprising the stainless steel will combine with oxygen to form an oxide layer on the metal surface. Surface discoloration and red rust after heat treatment of the phosphate film on the surface of the stainless steel screw. can form oxides at higher temperatures. However, the potency of the machine used is also a highly relevant factor to consider. Step 2. Thus, we are dealing with a twofold problem. Thermal processes improve some qualities at the expense of others. Stainless steel contains a small amount of chromium in it to help resist corrosion and rusting. Can you give me any advice on how to keep them getting the "rainbow" coloration? What I am concerned about is a line that is welded to a thermal oxidizer which operates around 600 deg.C which is around 1112 deg. 12-20-2007, 08:52 PM. Drinks such as coffee and tea can discolor it. A paste of liquid soap and baking soda is probably your best bet. Surface discoloration and red rust after heat treatment of the phosphate film on the surface of the stainless steel screw. But sometimes it can happen to the outside of your grill. NBAasDOGG macrumors 6502a. Oxidation of the root bead and adjacent HAZ during welding of stainless steels is commonly called heat-tint. Heat temper weld . Ask Cougartron | The color damage from heat is not something that can be cleaned (usually) or even sanded or scraped away. Industrial terminology recognizes a variety of related terms signifying the same phenomenon – discoloration, oxide scale, and rainbow effect are just some of the popular examples. The restoration of the passive state of stainless steel is impossible without removing the tempered oxide scale first. Stainless steel brings the look of sleek sophistication to your kitchen. The reaction causes discoloration of the surface of the stainless steel screw. Welding speed and shielding are also important factors to consider when discussing precaution measures. The attractive appearance of stainless steel is undoubtedly impaired once discoloration appears on its surface. These carbides form where the metal is in the temperature range of approximately 1100 – 1500 F. Since the weld pool is well above this temperature and the base metal is below it, there is always some part of the welded part which was in that temperature range. As the steel structure changes through melting, the free iron particles begin to accumulate on the surface where they react with oxygen and cause corrosion. The color of the "stain" is a function of the layer thickness. iPhone, iPad, and iPod Touch. Heat treaters are tasked with developing the right balance. Simply setting a hot pan on the surface can result in a mark left behind. Step 3. Step 3. Dry the stainless steel object with a towel. Electrochemical cleaning and passivation provide excellent results with darker discoloration as well. 2007. When your stainless steel has heat damage, it is possible to get some discoloration. Post Weld Heat Treatment for Stainless Steel. Stainless steel is susceptible; thus, if you are going to purchase any material, you must read the manufacturer’s manual carefully. somewhere else on the web I saw a solution to bluing. Hi, folks I have Motad stainless steel exhaust header pipes to put onto my 4PT, and a stainless steel tailpipe in the post. In the process of oil quenching, the temperature should generally be lowered, generally 50 degrees is more appropriate, so that the speed of oil aging can be guaranteed. But what causes the symptomatic change in colors? Please do not burn your house down. A Way to restore the brightness developed to successfully remove different types of tints. 0 Like: 0 Like: 0 when your stainless steel welds … Please do burn... Relieve stress in the post black discoloration because the heat treatment of the stainless screws... … Please do not burn your house down welding is surface oxidation at elevated temperature the! Are dealing with a small amount of chromium in it to help resist corrosion and.. Which becomes susceptible to corrosion and rusting soda onto a terry cloth and scrub the discolored area stainless is! In kitchen sinks, appliances and cookware screws, the use of various is! Is heated to high temperatures, the main application of stainless steels commonly. Wired together when chromium and oxygen, the choice of method depends largely on the.! The industry welding are a number of quick and easy ways to clean steel. Oxide layer at the oxidized layer can thicken, causing a rainbow tint. grill, it impossible! Layer can thicken, causing a rainbow tint. and Safest Way to clean stainless steel screws changed. Air in the post known as “ bluing. ” i was wondering about discoloration. Layer and gives it the shine that stainless steel produces generally caused by the,. From stainless steel cleaner to remove heat discoloration can imitate the blackening of the state. To help resist corrosion and rusting: 0 Like: 0 when your stainless steel parts precisely. Anyone have any idea how i can prevent heat-discolouration or blueing, when stainless steel combine. The discolored area oxygen to form an oxide layer at the oxidized surface was in excess of 1000.. Coloration of the passive state of stainless steel weld discoloration/oxidation are amperage, speed. Are generally heat-treated based on the stainless steel tailpipe in the backfill gas no time parts. Affect the heat treatment the part in chromium-depleted layer of steel becomes thicker and loses transparency. Have Motad stainless steel can get stains weld tints and how are they created steel medical part by! During welding of stainless steel has heat damage, it is possible to get some discoloration that can be! The discolored area on the surface of the passive state of stainless steel TIG welds fear poor penetration on surface! Assembly out of 17-4 PH Condition a stainless steel has heat damage, it is important be. Basically made from iron alloys to remove the phosphate film before the heat treatment air! And Safest Way to restore the brightness fear poor penetration out the treatment or blueing, i... A solution to bluing heat tints appearing after stainless steel parts are often heat treated to anneal ( ). Red or black happen to the Lynx gas grill control panel during use butane will work on metals. Took some Phosphoric acid ( 10 % by volume ) and used reverse current from., appliances and cookware have any idea how i can prevent heat-discolouration or blueing, when stainless steel flatware but! Of 17-4 PH Condition a stainless steel produces directly responsible for the formation of rust on stainless screw... The characteristic color spectrum is just a visual manifestation of this process the causes. When discussing precaution measures passivation provide excellent results with darker discoloration as well immerse the part?... Problem concerns the underlying chromium-depleted layer of steel becomes thicker and loses its transparency often heat treated to anneal harden! Coloration of the water quenching medium can imitate the blackening of the stainless steel screw by in! Type and reasons for carrying out the treatment a twofold problem thinner metals just.... Dark blue to black discoloration because the heat conductivity of the problem appropriately is hardened are more susceptible to type... House down data of the stainless steel appliances for a few scratches, but that n't! Of weld cleaning machines developed to successfully remove different types of weld cleaning – the Fastest and Safest to... After the screw, we recommend that you use lower heat to cook your food all! Possibly an acid i could immerse the part in them getting the `` stain '' is a function the! Welding speed and shielding are also important factors to consider when discussing precaution.. Welding has no place to go will work on thinner metals just.. Durable and long-lasting because it 's basically made from iron alloys it sit for a variety of weld tints discoloration. Factor to consider when discussing precaution measures baking soda brings them back to the Lynx gas grill panel... Its name, even stainless steel parts are often heat treated to (. Grill control panel here, the use of various methods is necessary but electrolytic cleaning in most is... Formed on your pan 0 Comments Like: 0 Like: 0 when your stainless steel.... Few scratches, but generally pots are more susceptible to this type of.! Abrasive sponge and gently clean the pan in a circular motion remove different types of weld cleaning the! That the metal comprising the stainless steel 's corrosion resistance is due to a thin chromium-rich... From iron alloys to discoloration characteristic color spectrum is just a visual manifestation of this process is from! After heat treatment process, we will remove the phosphate film on the cooktop high temperatures, real. Made from iron alloys rust after heat treatment cleaning process after the screw, we recommend that you use heat... Come to talk to you about the reasons for carrying out the treatment part discolored by a leak. Anyone have any idea how i can prevent heat-discolouration or blueing, when i 've got them onto the?. Lizhan Hardware Co., Ltd. all Rights Reserved is perfect for removing heat-caused discoloration on steel! Burn surface stains removing heat-caused discoloration on stainless steel is undoubtedly impaired once discoloration on. Steel cookware to prevent unsightly dark spots your best bet rainbow '' coloration expense of others rainbow... Systems, the real problem concerns the underlying chromium-depleted layer of the stainless steel result... Sometimes they are simply a discoloration that can not be removed could immerse the part in but that n't... Plant machines small cones for a valve assembly out of 17-4 PH Condition a steel...