COATING INSPECTION INSTRUMENT
A Coating Inspection Instrument is a device used to measure the thickness of coatings such as paint on metal surfaces. It helps ensure the coating meets required standards for protection and quality.
SURFACE PROFILE
SURFACE PROFILE
Refer to the measurement of maximum peak-to-valley depth.
MAIN METHODS
SURFACE PROFILE
Elcometer 122 Testex® Replica Tape
Available in 4 profile ranges.Consists of a foam with non-compressible mylar backing.
Foam side is rubbed into surface providing a permanent mould of the peak-to-valley profile.
Elcometer 124 Thickness Gauge
Measure peak-to-valley height of a surface profile moulded in the Replica Tape.Anvil pressure as required in standards.
Up to 5 mm.
Elcometer 224 Digital Surface Profile Gauge
Measures surface profile on either flat or curved surfaces up to 500 μm.SURFACE CLEANLINESS
Non Visible Contaminant
Detection & removal of soluble salts are important as they can accelerate corrosion & cause coating film to break down (through blistering & disbondment. Surfaces shall be tested for soluble salts prior to commencement of surface preparation.
Soluble Salt Testing
Simply detect if they are present
Verify if concentration is below permissible limit.
Test Method Principles:
i. Collect the Sample
ii. Test/Analyse the Sample
TESTING EQUIPMENT
A) Elcometer 135C Bresle Test Patches
Easy to peel off after test, leaving no foam on substrate, causing less damage as no need to scrape off residue
Thicker foam walls, easier to insert syringe needle
B) Elcometer 138 Conductivity Meter
Also referred to as conductivity probe
Non-salt specific test
More conductive the solution is, higher concentration of soluble salts
1μS/cm to 19.99mS/cm
C) Elcometer 138 Bresle Salt Meter
Measures conductivity of sample, then automatically converts this to show salt density
D) Elcometer 138 Bresle Salt Kit
All-in-one kit that contains Elcometer 135 Bresle Patches & Elcometer 138 Bresle Salt Meter/Conductivity Meter
CLIMATE CONDITION
When atmospheric conditions move outside of specified range for a coating, the quality of a coating cannot be assured and coating defects may occur. Continued measurement of environmental conditions is especially important when weather conditions change during the course of work/ during coating operations that take many hours to complete.
5 important environmental conditions
I) Surface Temperature
ii) Air Temperature
ii) Relative Humidity
IV) Dew Point
V) Wind Speed
TESTING EQUIPMENT
A) Elcometer 319 Dewpoint Meter
Hand-held or as remote data logging monitor
Magnetic surface temperature probe/Liquid temperature probe available
-20 to +80oC or -40 to +200oC
0 to 100% RH
B) Elcometer 212 Digital Pocket Thermometer
Stainless steel liquid or surface probe
Switchable between oC/F
-49.9 to +299.9Oc
WET & DRY FILM THICKNESS
Film Thickness
Refers to the depth or thickness of applied coating material
Can be measured at both the wet film and dry film stages
Wet film thickness (WFT)
Thickness of coating immediately after application & prior to any curing or solvent evaporation.
These are typically measured during the application process. A comb, also referred to as a notch gauge, is a tool that measures WFT. It contains a series of precisely measured notches or “teeth” along their side. Combs are available in a variety of shapes and contain different measurement ranges based on the number of notches on each comb and height interval between them.
2 main reasons to perform WFT measurements:
To verify if coating application process is on track to reach specified DFT
To verify film thickness when DFT cannot be measured after drying/curing
Dry film thickness (DFT)
Thickness of coating system once all solvents have evaporated and the coating has cured.
TESTING EQUIPMENT
A) Elcometer 112 Punched Wet Film Combs
Available in aluminium or stainless steel
25 to 3000 μm (metric) on 1 side & 1 to 118 mils (imperial) on the other side
Note: aluminium has a shorter lifespan & is not as accurate as precision formed stainless steel
B) Type II DFT Gauges
C) Elcometer 456 Coating Thickness Gauge
Available in separate or integral models (of probes)
Interchangeable probes (standard straight, anodising, mini, waterproof, soft coating, scan, right angle, telescopic, 45o, high temperature)
Separate model can measure DFT up to 31mm
Integral model can measure DFT up to 13mm
ADHESION TESTING
Importance of Adhesion Testings:
Quantify strength of bond between coating & substrate, or between coating layers or cohesive strength of some substrates. Routine adhesion testings are used as part of inspection & maintenance procedures to help detect potential coating failures (that result in additional costs of rework).
Types of Adhesion Testing
Pull-Off - Measures pull force required to remove dolly from coating
Push Off - Measure pressure required to push coating away from substrate
Cross Hatch/Cut -Fast, low cost, visual comparison for assessing adhesion of paint & powder coatings
TESTING EQUIPMENT
A) Elcometer 106 Pull-Off Adhesion Tester
Houses a spring arrangement which applied a lift force to the dolly as the tension is increased (via turning hand wheel)
Ranges available: 0.5 to 3.5/ 1 to 7/ 3 to 15/ 5 to 22/ 0.05 to 0.2 Mpa
20 & 40mm dollies available
B) Elcometer 506 Pull-Off Adhesion Tester
Measure pull-off up to 50MPa
14.2, 20 & 50mm dollies available
Small, ergonomic, lightweight – ideal even in confined spaces
C) Elcometer 108 Hydraulic Adhesion Tester
Push off adhesion tester
Up to 25MPa
Suitable for use on flat, concave & convex surfaces
Dolly size: 19.4mm OD, 3.7mm ID
D) Elcometer 107 Cross Hatch Cutter
4 sided cutter (with spacings of 1/1.5/2/3mm) allows adhesion testing on wide range of coating thicknesses up to 250 μm
Optional with ISO/ASTM adhesive tapes
ASTM D 3359 vs ISO 2409
HOLIDAY DETECTION
Importance of Holiday Detection:
A holiday refers to an exposed area or discontinuity within coating film where part of the substrate remains uncoated. These tiny voids can lead to premature coating failure as they expose substrate to atmosphere.
Examples: craters, pinholes, fisheyes & cracks.
TESTING EQUIPMENT
Low Voltage
High Voltage
TORNADO
SPRAYING EQUIPMENT
Two models: 71:1 & 43:1 - each available in three configurations:
Option 1
Trolley Mount with Product Suction Hose
Part Numbers: PSP71AL-TZ / PSP43AL-TZ
Option 2
Trolley Mount with Product Suction Hose plus 15m (49.2ft) & 1.5m Product Hose
Part Numbers: PSP71AL-T / PSP43AL-T
Option 2
Trolley Mount with Product Suction Hose, 15m (49.2ft) & 1.5m Product Hose plus Sagola PSAM 500 Airless Spray Gun with Reversible Airless Spray Tip Guard, GRACO RAC Tip Adapter & 19/40 Reversible Airless Spray Tip
Part Numbers: TN71-PS500-15 / TN43-PS500-15