From the job shop to the robotic assembly floor, it is vital that the product be made well and correctly coated for protection, aesthetics, and performance.
So, industries like automotive, aerospace, and those utilizing plating, anodizing, powder coating or other coatings need accurate coating thickness measurement. This is particularly important when the coatings play a critical role in preventing the corrosion or wear of metal substrates.
Properly applied coatings, with thickness measured in mils (.001 inch) or microns (.001 mm), are also essential for paint/coatings contractors and companies that coat a wide range of building and functional surfaces, including pipe. Accurate application and coating thickness measurement, in fact, are crucial to avoid coating breaches leading to corrosion of the underlying substrate. This can help to prevent leaks and other safety issues in a wide range of industries.
However, until recently conducting frequent laboratory-quality coating thickness tests throughout the manufacturing process or in the field has been difficult. Traditionally, this required meticulous sampling and preparation, as well as taking the sample to the lab for evaluation. Although portable coating thickness gauges are not new, most fail to provide the accuracy, speed, or simplicity required for anyone to conduct quick checks as needed on the production line or in the field.
Fortunately, handheld devices are now available that allow personnel to easily and quickly perform lab-quality coating thickness measurements. Some options offer instant coating thickness measurement of almost any non-magnetic coating on both ferrous (magnetic) and non-ferrous (non-magnetic) substrates. This is possible using only one hand, even on curved and complex surfaces.
By simplifying the process, industrial facilities and paint/coatings contractors and companies can increase the quality of their products and services from start to finish while optimizing cost.
The Many Benefits of Coating Thickness Readings
Coating thickness directly affects product quality, whether for automotive paint, electroplating, anodizing, or a wide range of other coating applications. For example, checking the paint coating consistency on a vehicle not only provides a product with a superior finish, but can also offer essential data about the consistency of the paint when it is wet.
Incorrect paint consistency can affect drying times or eventual flaking of the paint film. Too little paint coating and you are left with cosmetic issues in opacity, and protective issues like corrosion, wear and exposure. Checking coating thickness can also tell if auto bodywork has been done on a used car, which can help the customer or dealer make a good decision on pricing.
When specificity and adhesion matter in anodizing and electroplating, a coating thickness gauge should be able to read the thickness of the coating to the minutest measurement. This can play a major factor in preventing corrosion while optimizing the process by eliminating any excess use of the expensive plating product.
Another way a coating thickness gauge can make a significant impact is in testing anti-corrosion pipe coatings to find weak spots, where the coating is too thin and a breach of the coating could make the substrate susceptible to corrosion.
Knowing about these trouble spots can prevent a disaster well before it occurs. This might involve petrochemical pipes in a facility, water pipes in a home or office, or even the piping and tubing in an engine.
A nondestructive gauge is a perfect way to ensure that the pipe’s protective coating has not been applied too thinly or become so over time. Excessively thin coatings are more likely to be chipped or breached, which can lead to corrosion promoters like water or oxygen getting under the coating and accelerating corrosion in the substrate.
Simplifying Coating Thickness Measurement
Although traditional laboratory and online based coating thickness measurement techniques are useful in the right settings, they have lacked the simplicity and flexibility required for frequent spot checks. Often, this involves sampling, sample preparation, and taking the sample to the lab for evaluation, which requires the participation of staff adequately trained for the process.
Other conventional coating tests, such as scratch testing, have been destructive or invasive and damaged the sample. This meant that a product could not be returned to the production line, or that a coated surface had to be recoated or repaired in the field at additional expense. Also, since only a small portion of the component or facility may be tested, results may not be representative of the entire situation.
Consequently, various portable coating thickness measurement devices have been developed. However, these have not always provided the necessary accuracy or been sufficiently easy to use.
Another drawback is that in certain environments with multiple substrates, the devices typically either had difficulty determining the substrate or utilizing the correct test for the application. So, multiple measurement devices had to be used, which complicated testing and added cost.
Finally, typical coating measurement methods were usually unable to accurately measure curved or complex surfaces. This left pipe as well as convoluted component designs largely unable to be easily spot-checked for coating compliance.
In response, industry innovators have developed a number of advanced designs for handheld coating thickness test devices. For units used on the production line and in the field, these significantly improve accuracy, versatility, and ease of use.
One design example combines two of the most widely used measurement methods – magnetic inductance and eddy current – into a dual mode device that can measure the coating thickness of almost any non-magnetic coating on both ferrous (magnetic) and non-ferrous (non-magnetic) substrates.
Since this type of unit is able to automatically determine the substrate and use the appropriate measurement circuit, this enables instant, non-destructive testing on painting, plating, anodizing, and organic coatings with accuracy up to 0.1 um. Such testing takes less than a second to display the measurement.
Because the key to providing accurate, repeatable measurements is the operator’s ability to reliably make consistent contact between the instrument and the test surface, the type of unit also utilizes a spring-loaded probe to generate a consistent contact pressure with the measured surface. This integrated probe also includes built in edge guides to enable easy measurement of even curved and edged surfaces. To ensure device stability during measurement, the foot of the probe is also designed to provide a firm platform when placed onto the test piece.
A number of other design considerations in handheld coating thickness gauges can also simplify measurement and improve versatility.
In order to improve accuracy and durability on the factory floor or in the field, it is best for the unit to have no moving parts, other than the probe. Similarly, the unit should be impervious to vibration, with measurement independent of its orientation.
To save time during the testing process, he recommends utilizing a unit with a large screen that enables the quick reading of results. Those results should be able to be stored in the gauge and transferred to a computer and/or printer for documentation and averaging purposes. An instrument that stores many test measurements is best so operators can perform numerous tests before downloading the results.
Easier, more accurate coating and plating measurement with handheld units will help to improve quality checks wherever needed. So, defects can be immediately detected and corrective action undertaken to minimize scrap and faulty end products.
John Bogart is Managing Director of Kett US (kett.com), a manufacturer of a full range of SCOF and surface property analyzers for various industries.
FAQs
How thick is 1 mil coating? ›
What is a mil in relation to paint thickness? The terms “mil” and “micron” are units of measurement used by the paint industry to measure thickness. In the English system, a mil is a thousandth of an inch (i.e. 1 / 1,000th or 0.001” or 1.0 mil).
What is mils in plating? ›In the U.S., we use an Imperial unit of measure called “mil” to measure the thickness of coatings. One mil is equivalent to 1 thousandth of an inch (or 25.4 microns), but that's not the easiest thing to visualize.
What mil is standard paint thickness? ›The true wet film thickness lies between these two readings. In the U.S. the thickness of paint is expressed in mils (one mil equals 1/1000 of inch). The rest of the world expresses coating thickness in microns (1 micron = 1 millionth of a meter and 25.4 microns = . 001” inch or 1 mil).
Is 12 mil thicker than 6 mil? ›The bigger the number the thicker the plastic. Plastic sheeting comes in ranges from 1 mil to 100 mils! A "mil" A mil is a measurement that equals one-thousandth of an inch, or 0.001 inch.
How thick is 2 mils? ›This means that a 2 mil poly bag manufactured to nominal thickness would actually measure 1.8 mil, or 0.0018 inches thick.
How thick is 12 mils? ›Laminate is typically between 7mm to 12mm thick, with the 12mm option falling just short of 1/2 inch. On the other hand, the term “mil” is used to measure the thickness of sheet vinyl flooring. This unit is equivalent to 1/1000 of an inch, referred to as “thou” outside the USA.
How thick is 10 mil? ›10 MIL thickness = 0.010 inches thick. As a measuring unit of thickness, 1 mil = 1/1000 inches.
How thick is 20 mil? ›The most common term for vinyl, “mil” (not to be confused with millimeter) is a unit of measurement equal to one thousandth of an inch. Therefore, a 20 mil liner thickness is equal to 20 thousandths of an inch.
What does 12 mil thickness mean? ›Mil thickness is a common measurement in manufacturing. A "mil" is a unit of thickness equal to one thousandth of an inch (. 001 inch). To convert mil to inches, take mil and divide by 1000. Example: 2 mil/1000 = .002 inches.
What does 30 mil thickness mean? ›Mil is not short for anything – it is its own unit of measurement and stands for one-thousandth of an inch.
How thick should coating be? ›
Typically, a thickness of about 1.5 to 2.0 mils will work well. The more geometry you have on the part, the more variance you will likely have, as the part shape will affect the film uniformity. For parts that must handle harsh environments, you may need more film thickness.
How do you calculate coating thickness? ›Two measurements must be taken: one with the coating in place and the other without. The difference between the two readings, the height variation, is taken to be the coating thickness. On rough surfaces, micrometers measure coating thickness above the highest peak.
Is standard for coating thickness? ›These SRMs range in thickness from 6 μm to 2 mm and are sold directly to end users. The NIST Coating Thickness SRMs are standards that offer traceability to a National Measurement Institute (NMI) for the calibration of coating thickness gauges that employ magnetic principles.
What is the best mil thickness? ›5 MIL thickness: Best for items that require additional protection but have more chances of piercing through the bag, like things with sharp edges. 6 – 8 MIL thickness: Suitable for items that need the secured protection and need high puncture resistance.
Which is thicker 30 mil or 60 mil? ›While the thickness of 30 mil PVC is 50% less, the tensile strength at break is only 18% less than the 60 mil textured HDPE. Doubling the thickness from 30 mil to 60 mil for HDPE provides only slightly higher tensile strength than 30 mil PVC.
Which is thicker 6 mil or 20 mil? ›Fortunately, vented crawlspaces can be sealed with the proper installation of a crawlspace vapor barrier. Vapor barrier thicknesses range from 6 mil to 20 mil, with 6 mil being the bare minimum and 20 mil being the most heavy duty and puncture-resistant.
Is 4 mil thicker than 6 mil? ›The bigger the number of mils, the thicker the plastic sheeting. Here are some approximations with common items to help you understand. Four (4) mil plastic sheeting is about as thick as a piece of paper. Six (6) mil plastic sheeting is what your trashbags are made from in your kitchen.
How thick is 5 mil? ›When it comes to plastic sheeting, “mil” is not a millimeter, but a unit of measurement equivalent to one one-thousandth of an inch. A grocery store plastic bag for example is about . 5 mils thick or . 005.
What thickness is 3 mil? ›| mil | mm | inch |
|---|---|---|
| 3 | 0.07619 | 0.003 |
| 6 | 0.152399 | 0.006 |
| 10 | 0.254 | 0.01 1/64 in |
| 15 | 0.381 | 0.015 |
| Mils | mm | Inches |
|---|---|---|
| 55 | 1.397 | ~1/16th |
| 60 | 1.524 | ~1/16th |
| 75 | 1.905 | ~5/64th |
| 85 | 2.159 | ~5/64th |
Is 3 mil thicker than 5 ml? ›
A: 5 mil is . 005 inch thick for each side of the pouch. 3 mil is . 003 inch thick for each side of the pouch.
How many mils is 18 gauge? ›A gauge conversion chart can be used to determine the actual thickness of sheet metal in inches or millimeters. For example, 18 gauge steel, according to a gauge conversion chart, is 0.0478 inch or 1.214 millimeter.
What thickness is 8 mil? ›...
| Plastic Sheeting Conversions Thickness Table: Mil to Inches | |
|---|---|
| 1 Mil to Inches = 0.001 | 70 Mil to Inches = 0.07 |
| 8 Mil to Inches = 0.008 | 500 Mil to Inches = 0.5 |
The term "mil" is used to describe thickness in thousandths of an inch. In other words, "1 mil" is one thousandth of an inch, 3.5 mil is three and a half thousandths of an inch. Mil thickness can also be written numerically.
What gauge is mil? ›A “mil” is 1/1000th of an inch. This can sometimes mean a millimeter to people outside of the United States, so don't get confused! Gauge is (100) x (mils), so for example 0.3 mils = 30 gauge. To go from mils to microns, you multiply mils x 25.4.
What does 20 mils mean? ›A mil is a unit of measurement that is equal to one thousandth of an inch. Therefore, a 20 mil liner is equal to 20 thousandths of an inch and a 27 mil liner is equal to 27 thousandths of an inch.
What Gauge is 10 mil? ›Mil vs.
001 of an inch. A 20 Mil liner is . 020 of an inch thick, and a 25 Mil liner is a little thicker at . 025 of an inch thick.
When the two are compared directly, 20 mils is equal to 0.508 (nearly 1/2) mm.
How thick is 40 mils? ›| Conversions Table | |
|---|---|
| 30 Mil to Inches = 0.03 | 1,000 Mil to Inches = 1 |
| 40 Mil to Inches = 0.04 | 10,000 Mil to Inches = 10 |
| 50 Mil to Inches = 0.05 | 100,000 Mil to Inches = 100 |
| 60 Mil to Inches = 0.06 | 1,000,000 Mil to Inches = 1000 |
Which is thicker 20 mil or 20 gauge? ›
20 units - A 20 Gauge liner is 0.0185 inches thick. A 20 MIL liner is 0.0205 inches thick or approximately 11% thicker than a 20 Gauge liner.
Is lower mil thicker? ›This thickness is indicated as MIL (thousandth of an inch). 1 MIL is a measurement unit that equals 0.001 inch which is about the width of an average human hair. Generally speaking, higher MIL designation equates to a thicker and strong plastic sheathing.
What does 6 mil mean? ›A Mil is a unit of measurement used to measure the thickness of film in thousands of an inch; 1 Mil = 1/1000 inch. While simple in principle, it's very hard to visualize 1/1000 of an inch.
What mil is 80 gauge? ›| Gauge (ga) | Mil | Millimeter (mm) |
|---|---|---|
| 80 | .80 | .0203 |
| 90 | .90 | .0228 |
| 100 | 1.0 | .0254 |
| 120 | 1.2 | .0304 |
A 20 gauge liner means that the liner has a 20 mil bottom and a 20 mil sidewall. So a "Gauge" liner is typically a little bit thicker walled liner than its "Mil" counterpart.
How do you measure 25 mils? ›- 0.5 ml = ⅛ teaspoon.
- 1 ml = ¼ teaspoon.
- 2 ml = 1/3 teaspoon.
- 5 ml = 1 teaspoon.
- 15 ml = 1 tablespoon.
- 25 ml = 1 tablespoon + 2 teaspoons.
- 50 ml = 2 fluid ounces = ¼ cup.
- 75 ml = 3 fluid ounces = ⅓ cup.
The thickness varies from 1 micron to 2 microns per applied layer. How thick is a micron? To provide some perspective, 1 mil is 38 microns. For example, the thickness of clear coat on your vehicle is typically 1.5 to 2 mils or 57 to 76 microns.
Why is coating thickness important? ›Determining the thickness of a coating is important because it impacts the overall product's longevity, performance, and appearance. Exact thickness measurements are also critical for understanding the coating's capabilities and quality.
How thick is DFT coating? ›A common range of DFT is 50 – 100μm for powder coatings.
How do you calculate coating? ›WFT x VS / 100 = DFT so using the same above numbers (150 x 60 / 100) = 90 microns DFT). Dry Film Thickness / Wet Film Thickness x 100 = Volume Solid shown as a percentage (%) again using the above numbers it would be as follows; 90 DFT / 150 WFT x 100 = 60% VS. m2 per ltr = 10 x VS(%) / DFT in microns.
What is total coated thickness? ›
The Total Coated Thickness (TCT) measures the steel substrate as well as the metallic coating, resin coating and/ or paint film. If a Tata BlueScope Steel AZ150 coated product is labeled as 0.42mm BMT means that it will have TCT of 0.47mm.
How thick is coating in microns? ›Coating thickness can range from 20 to 100 microns (1 to 4 mils).
How much concentration of coating is acceptable? ›Film-coating formulations, depending on the properties of the materials used and the ultimate functionality of the coating required, commonly comprise 5%–35% (w/w) coating solids in the requisite vehicle (with the higher concentration range preferred for aqueous formulations), of which 60%–70% is polymer, 6%–7% is ...
What is a thickness standard? ›What is the purpose of Standards? Certified thickness Standards are used to verify the accuracy and operation of coating thickness gages and are an important component in fulfilling both ISO/QS-9000 and in-house quality control requirements.
What is standard plating thickness? ›Coatings are typically applied to a thickness of 0.003 to 0.010 inches (0.076 to 0.25mm), but can be up to 0.020inches (0.51mm) without detrimental impact to the coating properties.
Is 1 mil thicker than 1mm? ›A mil is a measurement that equals one-thousandth of an inch, or 0.001 inch. One mil also equals 0.0254 mm (millimeter). Thus a mil is not the same thickness as a millimeter. The term "mil" is not an abbreviation but a unit of measure.
Which is thicker 1 mil or 4 mil? ›1 MIL is a measurement unit that equals 0.001 inch which is about the width of an average human hair. Generally speaking, higher MIL designation equates to a thicker and strong plastic sheathing. The most common plastic sheeting sizes found in local hardware stores are 2, 3, 4 and 6 MIL poly sheets.
What mil is thicker 4 or 6? ›Four (4) mil plastic sheeting is about as thick as a piece of paper. Six (6) mil plastic sheeting is what your trashbags are made from in your kitchen. Ten (10) mil plastic sheeting is what your business card is often made from. Fifty (50) mil is the thickness of a dime.
What is thicker 2 mil or 4 mil? ›As their name might imply, 4 mil bags are 4 millimeters in thickness, making them a bit stronger than their 2 mil counterpart. So these resealable bags work better for storing heavier items, as well if you will be handling the bags frequently, or storing items for a longer period of time.
How thick is 10 mils? ›10 MIL thickness = 0.010 inches thick. As a measuring unit of thickness, 1 mil = 1/1000 inches.
How thick is 6 mils? ›
A mil is a measurement that equals one-thousandth of an inch, or 0.001 inch. Most human hair is One-thousandth of inch, or 0.001 inch. The most common size in the thickness rating for plastic sheeting is 6 mil. This is 6-thousandths of an inch, or 0.006 inch.
What mil plastic is best for covering windows? ›An 8'x50' roll of 4 mil clear poly sheeting will give you enough plastic to cover many windows.
What mil thickness are ziplock freezer bags? ›The standard household Ziploc® Brand sandwich bag is 1.5 Mil. The heavier freezer bags sold in stores are about 3 Mil. 2 Mil. is the standard industry thickness.
What does 7 mil thickness mean? ›A mil is a thousandth of an inch — . 001 inch. It is a typical manufacturing dimension. When we make a product we specify the thickness as a mil.
What is 6 mil poly used for? ›A: This 6 mil plastic sheeting is commonly used as a vapor barrier in between walls, under concrete slabs, etc. While this item could be cut to desired size, please keep in mind the higher the mil the thicker the film.
Is 3 mil thicker than 5 mil? ›The 5 mil is thicker than a 3 mil.
Which is stronger 4 or 6 mil plastic? ›The bigger the mil "usually" the stronger the plastic sheeting. There are exceptions to this. When you add string or scrim as it is called to the plastic a 6 mil string reinforced plastic sheeting film is stronger than a regular 6 mil plastic sheeting film.