What is Coating: Definition and 94 Discussions

A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both. The coating itself may be an all-over coating, completely covering the substrate, or it may only cover parts of the substrate. An example of all of these types of coating is a product label on many drinks bottles — one side has an all-over functional coating (the adhesive) and the other side has one or more decorative coatings in an appropriate pattern (the printing) to form the words and images.
Paints and lacquers are coatings that mostly have dual uses of protecting the substrate and being decorative, although some artists paints are only for decoration, and the paint on large industrial pipes is presumably only for the function of preventing corrosion.
Functional coatings may be applied to change the surface properties of the substrate, such as adhesion, wettability, corrosion resistance, or wear resistance. In other cases, e.g. semiconductor device fabrication (where the substrate is a wafer), the coating adds a completely new property, such as a magnetic response or electrical conductivity, and forms an essential part of the finished product.
A major consideration for most coating processes is that the coating is to be applied at a controlled thickness, and a number of different processes are in use to achieve this control, ranging from a simple brush for painting a wall, to some very expensive machinery applying coatings in the electronics industry. A further consideration for 'non-all-over' coatings is that control is needed as to where the coating is to be applied. A number of these non-all-over coating processes are printing processes.
Many industrial coating processes involve the application of a thin film of functional material to a substrate, such as paper, fabric, film, foil, or sheet stock. If the substrate starts and ends the process wound up in a roll, the process may be termed "roll-to-roll" or "web-based" coating. A roll of substrate, when wound through the coating machine, is typically called a web.
Coatings may be applied as liquids, gases or solids.

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  1. M

    How to include an ITO layer for Anti-Reflection Coating in Silvaco?

    hello i use silvaco tcad 2016 for solar cell simulation i want to define ITO as an anti reflective coated layer on the menu of go atlas thanks
  2. S

    Powder coating: way to add more positive charge?

    I am thinking of powder coating at home. I know the part to be coated is negatively charged because it is grounded. I assume the powder is positively charged by the gun. I wonder if there is a way to add more positive charge cheaply to an inexpensive gun like the one at harbor freight? I think...
  3. B

    I Flow rate calculation of coating application

    Dear all, I'm currently working on a basic coating application and I'm struggling to get the flow rate stable. I'm trying to figure out how to calculate the theoretical flow rate in the application. The coating is stored in a pressure tank, which we put on an overpressure of 15psi. From the...
  4. DiveshAggarwal

    Help with depositing a Nano coating on a glass-like substrate please

    Can someone help me with the method for performing nano-coating on glass like substrate
  5. Steven Bolgiano

    I Thermodynamic Pros/Cons coating light metal tanks with rubber

    Hi Folks, I promise there is an actual question at the end of this note. I couldn't see where to attach images on this forum page, so here is a link to a rough illustration and a photo of the project site in progress (the cabinet for the digester is partially built)...
  6. J

    Mirror coating and BSDF measurement costs?

    I need an epoxy/polycarbonate substrate diffuser film similar to this one https://www.luminitco.com/products/light-shaping-diffusers mirror and hard coated. I have two films sized 100x100mm each (3.93x3.93 inches or 5.57'' diagonal ). I have no idea what this will cost. What's the expected...
  7. R

    Trivalent conversion coating on aluminum

    Hi! Is anyone familiar with trivalent conversion coating on aluminum? I'm struggling with unrepeatable and too high values of contact electrical resistance of coating. I would really appreciate any advice how to deal with that coating. Thanks a lot!
  8. A

    Hydrophobic coating on acrylic/plexiglass, PTFE or other solution?

    I need to make the surface of a milled acryl/plexiglass surface to have as low of a friction as possible, I am looking online and the only real and also cheap solution I see is the spray aerosol teflon/ptfe, the question I would have is is this the best solution and will it be effective? I read...
  9. ContagiousKnowledge

    Electromagnetic waves incident on an anti-reflective coating

    We're trying to prove this: There exists 3 distinct regions: Region 1 has index of refraction 1 and lies before light hits the coating. For simplicity, define the position of the interface between the air and the coating z=0. The second region is the coating, which has index of refraction √n. At...
  10. S

    I I Want to Remove a KTP Crystal's Coating

    I want to make an optical parametric amplifier and am considering using a KTP crystal from a laser pointer. The problem is the KTP seems to have a coating that filters 1064nm light which I want the OPA to produce. I've tried to remove the coating using nail polish remover (acetone), but that...
  11. T

    I How can I go about making a "Space Proof" coating?

    So I am planning on launching a Satellite to promote the Dogecoin cryptocurrency. One of the main points is printing/painting (Or whatever) the logo on the side of a metal panel. How can I make it so it doesn't melt off or turn white from radiation so quickly?
  12. T

    Heat Transfer II -- What is the purpose of a silvered coating?

    Homework Statement (a) What is the purpose of a silvered coating, usually of a good conductor, on the outside of most insulation? The Attempt at a Solution [/B] The silver coating on the outside of most industrial pipes and lagging (Insulation) is primarily to reduce the surface’s...
  13. A

    Electroless nickel coating of confined spaces

    Hi, I am conducting some experiments with the electroless nickel (EN) coating of the free machining brass (high lead contain material, which is not good for coating but I must use this material). After surface cleaning and etching procedure, once the brass is submerged in the EN coating...
  14. K

    How do interference and AR coatings work?

    How does AR coating works on cameras? How do they decrease reflection? And how does it improve the quality?
  15. J

    Which Materials would be best for IR Ceramic Coating

    Which materials would be best for an IR reflective/opaque coating to improve the efficiency of ceramic insulation materials for use in kilns and furnaces, meant for continuous use at up to 2500 deg F? I understand that materials might be useful for different wavelengths of IR, so details...
  16. N

    Why the diamond-like-carbon coating works well with water?

    Hi everyone. I have a question with a DLC (Diamond-like-carbon) coating. In many papers, the DLC coating without hydrogen (a-C or ta-C) shows very good frictional properties and wear resistance with water lubrication. I'm studying on eco-friendly engineering, so I surprised that water can be...
  17. J

    Coating Eyeglass Lenses(destructive interference)

    Homework Statement Eyeglass lenses can be coated on the inner surfaces to reduce the reflection of stray light to the eye. If the lenses are medium flint glass of refractive index 1.62 and the coating is fluorite of refractive index 1.432, (a) what minimum thickness of film is needed on the...
  18. S

    Effect of IR blocking nano coating atop solar reflectors....

    I'm needing to reflect additional solar into a greenhouse to increase plant beneficial PAR light (400-700nm) while restricting and minimizing excessive IR heat also building up inside, too. I'll be using 400 sq ft of flat plate reflectors (40'X10') at ground level horizontally positioned along...
  19. T

    Nonreflective Coating and Emission Relation?

    Hi all, I've been able to find the answers to most of my questions in these forums, but this time I was not able to. So here goes my first post: I've been learning about thin film interference, and it all makes sense to me except for the correlation between destructive interference caused by...
  20. R

    A Conductivity change of a tank (glass coating on steel)

    Suppose I have a tank which is made of steel coated with a thin layer of glass on the inside to protect the steel from corrosion (the material stored inside the tank is corrossive; say for arguments sake Water with 10% Hydochloric Acid). In theory, till the glass is intact there is an...
  21. S

    Why is dielectric material used for anti-reflective coating?

    Why is dielectric material used for anti-reflective coating? / Why not use a material this is NOT a dielectric material? Is it because dielectric materials are highly transparent?
  22. Titan97

    Covering half of lens with an opaque coating

    Homework Statement hat happens to the image of an object kept before a lens if the upper half of lens is covered by an opaque coating? (The object is kept at a distance $1.25f$ before the lens. Half the object is above the principle axis. $f$ is the focal length of lens). Homework...
  23. Khoa

    Measure thickness of coating film on Zinc Plating Steel

    Hi All, I'm searching for the possible method to determine organic coating thickness cover on steel tole was plated by thin zinc layer. Additionally, I also want to measure thickness zinc plating layer in between these layers (coating on top & steel on bottom) without destructing them. Please...
  24. Shadow-Shocker

    Can PEG waterproof wood without altering its appearance?

    Hello I found a recipe for making a type of waterproof wax using beeswax and paraffin wax, and I plan to coat this type of wax with a piece of wood. Does anyone know with this type of wax, after coating the piece of wood, will the wax still prevent the wood from expanding in water?
  25. spareine

    In low-e glass, is infrared able to reach the low-e coating?

    A low-e coating in double glazing should reflect long wavelength infrared rays (LWIR, 8-15 µm). However, glass absorbs LWIR. (For example, thermal imaging camera's cannot see through glass.) Are long wave infrared rays able to reach the low-e coating?
  26. genxium

    Is there any screen of cellphone equipped with DLC coating?

    It's kind of strange to me that when reading topics like "components of cellphone screen", people often mention an outermost anti-reflecting coating which takes advantage of destructive interference. There're few mentions for using DLC-coating as a cellphone screen outermost coating but...
  27. Mat B

    Help with electrically non-conductive fabric? (500V)

    Hi all, My first post, so kind of excited! I'm looking for an electrically non-conductive fabric, or material that can be spun into a fabric. I'm looking to hold back 400-500V. Ideally thin, and highly pliable. A fabric coating may also work. Any and all thoughts and insights are sincerely...
  28. Ornit

    Ion Assisted Deposition (coating technology)

    Hi all, When talking to some of our optics vendors, I got the impression that Ion Assisted Deposition (IAD) is standard. We use our optics at high power densities and we care about laser damage as well as adhesion and density of the coating (aka porosity, helps reduces sensitivity to humidity)...
  29. I

    Possible webpage title: Coal Dust for Snow Removal: Effective or Hazardous?

    Hi I have a project where I am trying to make a coating or paint that will give off heat when an electrical current is passed through it. I got graphite powder and made it into a paste and allowed it to dry on a substrate. The problem is that it is highly resistive (a small section has a...
  30. 1

    Deriving the Point Image Equation for a Spherical Interface

    Homework Statement A biconvex lens of refractive index ##n## and radius of curvature ##r## and focal length ##f## floats horizontally on liquid mercury such that its lower surface is effectively a spherical mirror. A point object on the optical axis a distance ##u## away is then found to...
  31. N

    Circuit to detect conductive coating.

    Basically to detect whether a lens has EMI coating or not.
  32. kelvin490

    Coating Hollow Shapes w/ Vacuum Evap: Atom vs Ion?

    Is it possible to use vacuum evaporation, sputtering and ion plating processes to coat the inside walls of holes and other hollow shapes of substrates? I wonder whether the source materials are ejected in the form of atoms or ions? Many books say atom but how can they travel to the substrate if...
  33. A

    Coating that is both reflective and thermally conductive

    I have an electrical enclosure that sits in direct sunlight and must use passive cooling. Does anyone know of or have ideas on where to find information about a finish for aluminum (380A) that is both reflective of sun radiation while allowing thermal energy generated within the enclosure to...
  34. M

    Thin film interference and anti-reflective coating

    Hi, I actually have two questions that are somewhat related so I am including them in one post. I add much more detail about the system then probably necessary because I'd like to see if I have a correct understanding of how the system works in addition to the question itself. Please bear with...
  35. caters

    How is coating with an oxide oxidation

    I looked up the word oxidize and one of the definitions is to make it an oxide which is what happens when iron gets rusty(even though there is also iron hydroxide in rust). Another was to coat with an oxide. Now how is coating with an oxide oxidation? Does it catalyze the oxidation by...
  36. S

    Enhance Visibility with Metal Spray Coating for X-Ray Applications

    Hello fellows, i would like to ask if you might know any spray with metal elements which can be visible in X-rays. I want to use it as coating in objects. Does any common gold or plat spray be used? Thank you!
  37. Solarmew

    Anti-reflective coating confusion

    My professor confused me today :( I'm trying to figure out the thickness of an anti reflection coating and it looks like from the equation 2ndcos(Θ) = mλ that for a given λ the thickness of the film should increase for incidence slightly away from normal. But he said that intuitively it...
  38. P

    Pressure Coating Issues: Even Layer Not Achieved

    I have assembled a simple roller transfer mechanism for applying thread sealant ( toothpaste consistency ) to external threads. Since I did not get uniform coating, I placed the unevenly coated component in a small pressure vessel at 3 kg/cm2, hoping that the pressure would even out the uneven...
  39. A

    Characterization of coating layer

    Hi everyone, can anybody suggest a characterization technique for a coating layer. i have a polymer substrate, then coated with polymer binder, than coated with metal. if i using FTIR i only obtain spectra for organic which is polymer. can i use XRD, XPS ...? any suggestion with...
  40. A

    Thin-Film Interference and Antireflective coating

    Homework Statement A pair of eyeglasses has an index of refraction n-glass = 1.52. It is covered with an antireflection layer that has a thickness of 120 nm and an index of refraction that is less than n-glass. If the antireflection layer is designed to minimize reflection in the middle of...
  41. R

    Coating a Stainless Steel Lab Reactor

    We have a small lab reactor (~2 Litres) made of stainless steel that we use to test reactions. Unfortunately, we now have one test which has a hot acidic environment (dil. HCl approx. 20%) that would corrode the native stainless steel. Is there any way to work around this? Maybe a...
  42. B

    What are the two requirements for an anti-reflection coating?

    Homework Statement What are the two requirements for an anti-reflection coating? Homework Equations Not sure there are any. The Attempt at a Solution I googled the term anti-reflection coating and I found a wikipedia article on it here...
  43. W

    Contact angle and anti reflective coating.

    Hi all, just want to ask is there any correlation between the contact angle of a anti reflective coating? i.e the bigger the angle, the better the anti reflective coating? Thanks in advance.
  44. C

    Designing a polymer coating process

    Hi everybody. My goal is to design a process that, with no automated machinery (I'm using a mechanical pipette), would allow for extremely uniform coverage (that is, with minimal area of multilayers or empty spaces) of a hydrophilic surface with a thin film of polymer solution. I would...
  45. S

    Thickness of AntiReflection Coating for destructive interference

    Homework Statement Glass, despite being transparent, still reflects a little bit of light. When making lenses and such, you'd rather not waste any light with stray reflections. Fortunately, you can use destructive interference to suppress those reflections. The picture below shows a piece of...
  46. T

    Problem with light manganese phosphate coating (parkerizing)

    Hello all, We have a manganese phosphating process for gun parts and I am having trouble with some parts coming out with a lighter coating than normal. Our orginal steps which, for years, have produced repeatable high quality results are; Sand blast with aluminum oxide, phospahte bath at...
  47. R

    Need high-temp rubber coating

    Need high-temp "rubber" coating Hey I'm looking to coat some 0.5" aluminum rods with some sort of coating to increase the friction coefficient ("tackiness" I believe it's called). It will be used in high temperature environments of up to 200C. Does anyone know of such product? I tried...
  48. D

    High Temperature Dielectric Coating

    I'm looking for some sort of dielectric coating that can be used at high temperatures. I'm working on trying to create a voltage point charge in a high temperature steam environment using a coated accupuncture needle. The goal is to be able to coat the needle thinly and uniformly, leaving only...
  49. F

    Anti-reflection coating and FULL reflection coatings

    Hello Forum, to obtain good anti-reflection at one specific wavelength, a layer of the right index of refraction is deposited on a certain surface. The layer thickness must be d=lambda/4... This achieves better transmission. If we used multiple layers we would get even better transmission...