VARNSIH ADHERENCE - GB/T18103-2000 (6.3.5) and GB/T4893.4-1985 (adapted)

1. TOOLS
1.1 Handheld multiple blade device
1.2 Medical grade tape
1.3 Pig hair brush
1.4 Observation lamp equipped with a 60 W white sandblasted light bulb
1.5 4 X magnifying lense

2. SAMPLING
1*250 mm x product width . Samples’s varnish should be completely dry and free from scratches or bubbles

3. ENVIRONMENTAL CONDITIONS
Temperature: 20 (+/-2) ° C  
Humidity: 60-70%

4. TESTING PROCEDURE
4.1 Select three testing areas covering 3 different wood structures of the sample
4.2 The centre of each testing area should be minimum 40 mm away from the sample edge
4.3 The centre of any testing area should  be minimum 65 mm away from the centre of any other testing area
4.4 Using the handheld blade instrument, effect one 35 mm horizontal and one overlapping 35 mm vertical cut on the varnish (grid)



4.5 Effect the cuts at a 45 ° angle from the main wood structure
4.6 Gently brush off any debris from the grid



4.7 Apply the tape diagonally over the grid; press the tape firmly onto the grid
4.8 In a single, strong movement, pull the tape off the grid



4.9 Place the sample under the lamp and check the flaking with the help of the magnifying glass; checking should be done at different angles from the light

5.ASSESSSING TEST RESULTS

VARNISH ADHERENCE GRID TEST Test Results Grading
Grade	Explanation	Illustration of affected area
0	Lines are clean and complete. No square is flaked off.
1	Minimum flaking at intersections. Flakes cover less than 5% of the grid.
2	Flaking at intersections and lines. Flakes cover 5-15% of the grid.
3	Major flaking at intersections, lines and squares. Flakes cover 15-35% of the grid.
4	Major flaking at intersections, lines and squares. Flakes cover 35-65% of the grid.
5	Flaking exceeds level 4.