Paint

MICROLAB is involved in testing the quality of paint as well as its adhesive properties to give suppliers the confidence to move ahead with the most economical option to suit the application with high accuracy and reliability. The application industry varies from automotive to earth movers as cost reduction and corrosion resistance is the order of the day. The list of paint properties include.

VISUAL
Colorimeter & Spectrophotometer

The color of the paint can be characterized at MICROLAB with the below color space:

CIEL*a*b*C*h* ;CIEL*a*b*;CIEXYZ;

CIERGB; CIEL*u*v*; CIEL*C*h;Yellowness & Whiteness ;Color Fastness

The light source can be controlled to be D65/D50/A

Sag Measurement

Sagging tester is in compliance with ASTM D4400 and D3730. These are tested to determine the relative sag resistance of the paints in order to provide technical parameters on application

MECHANICAL
Tubular Impact

The resistance of the coating to a falling weight can be determined by this method as per ISO 6272.1

Different weights can be chosen with a maximum height of drop being 100cm

Scratch Resistance

The ability of the coating to withstand a scratch deformation is evaluated. There are 2 methods currently carried out:

  • a. Constant Load Scratch
  • b. Varying Load Scratch Resistance

As the name implies, a constant load or a varying load can be chosen along with the type of indenter ( steel, carbide etc) used to scratch the surface. A variety of test methods are followed ranging from ASTM, ISO and customer developed standards

Pencil Hardness

The hardness of the coating is also evaluated using pencil hardness. Increasing hardness of pencil tips is rubbed against the surface and the hardness at which we see the coating deform up to the substrate is noted. The standard that is followed for this method is ASTM D 3363, ISO 15184

Pendulum Hardness

The damping property the coated material is determined using a pendulum hardness tester. This is calculated by the number of oscillations. The hardness of any given coating is given by the number of oscillations made by the pendulum within the specified limits of amplitude. The primary standard that is followed for this test is ASTM D4366

CHEMICAL
ROHS in Paint

Hazardous elements in paint can be tested by a variety of test methods present at our facility.

Different elements like Lead, Cadium, Mercury, Chromium, PBB, PBDE can be evaluated using GC-MS, ED-XRF and ICP-OES up to very small levels of concentrations.

Chemical Composition/Identification

The type of paint that is used (for example, PolyUrethane, Epoxy etc.) can be identified using FTIR (link). The IR spectrum is used to study the type of paint and is a very quick method of identification.

THERMAL PROPERTY
Heat Temperature (HDT)

HDT is a relative measure of a materials ability to perform for a short time at elevated temperature while supporting a load.

It gives an indication at what temperature materials start to "soften" when exposed to a fixed load at elevated temperatures.

  • ATSM D 648-07: Standard test method for Deflection Temperature of plastics under flexural load.
Flammability

Flammability is the ability of a material to burn or ignite, causing fire.

Under certain applications Plastics may reach a point of deformation, melting or ignition due to high temperatures. To limit this failure, Flammability property is checked to give an idea about the material selection. The burning behavior of plastics is not just a material characteristic; it also helps with the designing.

  • ASTM D 5132 : Horizontal Burning Rate of Polymeric Materials Used in Occupant Compartments of Motor Vehicles.
  • ISO 3795: Determination of burning behavior of interior materials
Differential Scanning Calorimetry (DSC)

This technique is used to measure the energy changes in the paint (entropy) as a response to the temperature. This is very helpful in finding the glass transition temperature of coatings (Tg) which will then determine if the coating can be used in different environments. Curing property of paint can also be found, and other applications include determining the moulding temperature for plastics, crystallinity of plastics etc. It is important to have the temperature at sub-zero temperatures as some polymers have their Tg values in this range. At Microlab, the temperature range is between -120oC to 720oC

Thermo- Gravimetric Analysis (TGA)

TGA is useful to provide the profile of the paint that is used, the fillers and other constituents that make up the final coat. TGA is extremely useful when trying to diagnose the reason for a coating failure. Other applications include: reverse engineering, complete polymer profile, and filler content concentration

Thermal Conductivity

Thermal conductivity is an important property when trying to design materials as insulators and in heat exchanger applications. At Microlab we can also test the thermal conductivity at different temperatures ( from -50 o C to 200 o C ), on liquids, powders and solids. Application can be extended to batteries, fluids, building materials, explosives, lighting etc. Our facility is equipped with 2 types of equipment: the steady-state measurement can give precise values while the MTPS (Modified Transient Plane Source) instrument can provide values within seconds.

The standard test method for analysis follows ASTM C518, ASTM D7984 and ISO 8301

SITE TESTING FOR PAINTS
Adhesion test

This test is used to check the compatibility of the primer with a surface or even between 2 paint coats. We carry out different adhesion tests as below:

X-Cut: This test is performed as per ASTM D3359. A cut in the shape of ‘X’ is made on the coating. This test is qualitative

Cross-Hatch: In this method, a cross-hatch pattern is made instead of ‘X’, and a tape is applied to the surface, Once the tape is lifted off, the remaining cross-hatch is studied for its adhesion property. This is also a qualitative test, and is performed as per ASTM D3359

Pull-Off test: A dolly is stuck onto the coated layer with a strong adhesive. Using a portable pneumatic device, a tensile force is then applied increasingly until the dolly is pulled off. The standard procedure is as per ASTM D4541 and ISO 4624

Conical & Cylindrical Mandrel: Different diameter cones are used from minimum 3mm and 32mm are used to check the diameter at which the coating gets peeled.

Salt Contamination Test

The presence of salts on the blasted surface decreases the adhesion of the coat with the surface. The surface has to be checked for the salt content before application begins. If this is avoided, the paint system may show blisters or peeling off with time.

Determination of the concentration of soluble salts (salt contamination) on metal surfaces is carried out in accordance with ISO 8502-6, 8502-9.

Dry Film Thickness (DFT)

Dry Film Thickness can also be measured on the coated sample at your site.

Surface Roughness

Surface roughness is important to create a good bond between the paint and the substrate. If the surface is too smooth, the tendency of the paint to adhere to the substrate will drop. On the other hand, if the substrate is too rough, a large volume of paint will be required to create the same DFT needed to form a proper coat.

Holiday Test

To check if there are pinholes or defects in the coating, a holiday test is performed. Pinholes are formed if the curing of the paint is not as per specification and are hard to catch visually. These are small pockets of space which later enlarge causing corrosion to the substrate.

Coating Thickness Mesurement

Pull off Test

Refractrometer

Salt Spray Chamber

Surface Roughness Tester

Tubular Impact Test

Variable Load Scratch Tester

S.No Specific Test Performed
1 Coating Thickness
2 Accelerated Storage and Stability Test
3 Colour
4 Consistency - Flow cup
5 Drying Time
6 Residue on Sieve
7 Chromic Anhydride
8 Pigment Content
9 Xenon Exposure Accelerated Weathering
10 UV-Exposure Accelerated Weathering
11 Natural and Artificial Weathering
12 Volatile Matter
13 Volume Solids
14 Wet Opacity
15 Protection against Corrosion under condensation
16 Tubular Impact
17 Scratch Hardness (As per IS 101)
18 Fineness of Grind
19 Finish
20 Flash Point
21 Flexibility and Adhesion -Bend Test as per IS 101
22 Gloss 60 deg
23 Mass in kg/10L
24 Phtalic Anhydride Content
25 Pressure Test
25 Pressure Test
26 Resistance to Acid
27 Resistance to Alkali
28 Resstance to Chlorine
29 Resistance to Heat
30 Resistance to Petrol
31 Resistance to Lubricating Oil
32 Lead in Paint by XRF
33 Lead Restriction Test
34 Ash Content
35 Barcol Hardness