Before applying any protective coating, confirming the cleanliness of a blasted surface is a step that should never be skipped. Dust particles (often invisible to the naked eye) can significantly impact coating adhesion.
This is where the PosiTest DT Dust Tape Test Kit comes into play. Designed in compliance with ISO 8502-3, the PosiTest DT provides a reliable and standardized method to detect and evaluate dust on blast-cleaned surfaces, ensuring they are clean and ready for coating.
Why Dust Testing After Blasting Is Important
After abrasive blasting, even surfaces that look clean to the naked eye may still contain fine dust particles. These particles can compromise coating adhesion, leading to premature failure or corrosion, especially on steel substrates.
To mitigate this, most industrial painting and coating specifications mandate a dust test before coating application. Dust must be within allowable limits defined by standards to ensure the coating performs as expected.
Common Sources of Dust on Prepared Surfaces
Dust can settle on the surface from several sources, including:
- Residue from abrasive blasting
- Airborne soil or particles carried by wind
- Environmental conditions on site
Dust tends to accumulate in specific areas, such as:
- Horizontal surfaces
- Structural cavities
- Inside pipes and confined spaces
Because much of this dust is invisible to the naked eye, visual inspection is not enough. That’s why a standardized tape test, like the one performed with PosiTest DT, is necessary.
What is the PosiTest DT Dust Tape Test?
DeFelsko PosiTest DTThe PosiTest DT Dust Tape Test Kit is a complete solution for conducting dust testing in accordance with ISO 8502-3. It helps assess both the quantity and size of dust particles on blast-cleaned surfaces before painting.
This method not only confirms if the surface meets the cleanliness standards but also provides a documented record of the surface condition at the time of inspection.
Where Can It Be Used?
The test is suitable for surfaces cleaned to ISO 8501-1 Grades A, B, or C, making it ideal for projects involving steel substrates and industrial coating systems.
What’s Included in the PosiTest DT Kit?
The PosiTest DT Kit typically contains:
- Dust Test Comparator Display Board (with black, white, and two-toned backgrounds)
- Transparent Display Board
- Spring-loaded roller (for uniform tape application)
- Adhesive tape roll
- 10x magnifier
- Dust Test Report Form
- Scissors
- Disposable gloves
- Pictorial reference for dust quantity and size
How to Perform the Dust Tape Test Using PosiTest DT
Step-by-Step Procedure:
1. Discard the First Few Turns of Tape
Remove and discard the first 3 turns of tape from the roll to avoid contamination.
2. Cut the Tape
Cut a piece approximately 20 cm (8 inches) long.
3. Apply the Tape to the Surface
Press 15 cm (6 inches) of the tape onto the test area using one of the following methods:
- Thumb Method: Apply firm pressure with your thumb, moving it across the tape 3 times in both directions. Each stroke should take 5–6 seconds.
- DeFelsko Tape Roller: Place the roller over the tape and move it 3 times in each direction with a consistent downward pressure between 39.2N and 49.0N.
4. Remove and Mount the Tape
Carefully peel off the tape and place it on the Transparent Display Board to preserve the dust sample.
Visual Assessment: How to Evaluate the Tape
1. Dust Size Classification
- Place the display board over the black, white, or two-toned strip — choose the one that offers the best contrast.
- Use the included 10x magnifier if needed.
- Compare the particles to the dust size classification guide and assign a size class from 0 to 5.
|
Class |
Description of Dust Particles |
|
0 |
Particles not visible under 10x magnification |
|
1 |
Particles visible under 10x magnification but not with normal or corrected vision—usually particles less than 50 µm (2 mils) in diameter |
|
2 |
Particles just visible with normal or corrected vision—usually particles between 50 µm and 100 µm (2 and 4 mils) in diameter |
|
3 |
Particles clearly visible with normal or corrected vision—particles up to 0.5 mm (20 mils) in diameter |
|
4 |
Particles between 0.5 mm and 2.5 mm (20 and 100 mils) in diameter |
|
5 |
Particles larger than 2.5 mm (100 mils) in diameter |
2. Dust Quantity Rating
- Visually compare the tape sample against the pictorial references (Ratings 1 to 5) on the Dust Comparator.
- If necessary, you can use half steps (e.g., 2.5) for more detailed results.
- Note: A fully discolored tape with fine dust is rated as Quantity 5, Size Class 1.
Recording and Reporting the Results
1. Attach the used tape onto the Dust Test Report Form.
2. Record the:
- Dust Quantity Rating
- Dust Size Class
3. Conduct a minimum of 3 tests per surface type. If the ratings vary by more than one level, perform 2 additional tests and calculate the average.
What If the Surface Fails the Dust Test?
If the dust level or particle size exceeds the specification limit:
- Use clean, dry compressed air or a suitable air blower to clean the surface.
- Repeat the dust test to ensure compliance before proceeding with coating.
Applicable Standard
All testing should be done following ISO 8502-3: Preparation of steel substrates before application of paints and related products – Tests for the assessment of surface cleanliness – Part 3: Assessment of dust on steel surfaces prepared for painting (tape method).
This standard ensures the test is repeatable, objective, and acceptable across projects.
Dust Tape Test Distributor in Singapore
LFC PTE LTD is the authorized distributor of DeFelsko PosiTest DT Dust Tape Test in Singapore. Our expert team can assist you in selecting the appropriate solutions for your needs.
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