The crack test is the way that you test the canvas print thickness.
You can take an uncoated canvas and fold it and notice how it cracks.
The structure of the inkjet canvas is made of grid which is created by the warp and weft weaving method.
The surface of the canvas is coated with white layer of prime coating formula which absorbs the ink and gives it the right color.
That canvas structure and the prime coating are the cause for the cracks when folding the canvas.
While varnishing the canvas and coating it with Star-Lac varnish you give your canvas print the durability to eliminate the cracks and also to be protected against abrasion.
The varnish liquid is absorbed into the canvas and also makes a Flexible layer on the canvas surface, thanks to these features we can fold the canvas print and also do the gallery wrap without seen any cracks.