Green Grab refers to an adhesive's initial bond strength and when combined with faster curing, reduces timber flooring movement during installation to minimise hollow spots without the need to fix or weigh flooring down. Faster curing also means the floor can be put into use sooner.

To gain factual insight into the difference in Green Grab performance and curing time of various adhesives we recently set up and conducted comparison tests to assess green grab, early tensile strength and the relative curing performance between Bona silane flooring adhesives and other leading competitor adhesive brands available in the Australian market.

For testing purposes, Blackbutt overlay blocks 64 x 260 x 14mm were used. The blocks were laid into the surface, twisted slightly, straightened and pushed down again to ensure the best contact with the adhesive. Each block was fixed so that 1/3rd of its length was left ‘hanging’ over the edge of the plywood substrate, unsupported, with 2/3rds of its length being adhered to the substrate.

All adhesive application was done using the same 1000g trowel size to ensure identical application rates.

30 minutes curing time was allowed after the placement of blocks before testing. Tests to ‘lift’ the blocks were then conducted at 15 minute intervals under the same conditions. To facilitate this, 5 individual blocks for each adhesive were laid, and each marked with the elapsed time in minutes for lifting: 30 / 45 / 60 / 75 / 90

Testing was carried out using a crane scale with measurements in Kg. The crane scale was set in place and slowly lifted upwards until the pulling rope contacted the underside of the block, and then the Tare set. Slow consistent vertical movement was then applied and pressure increased until the point of failure where the block ‘lifted’ and lost adhesion to the substrate. The highest recorded figure at the point of failure was recorded for each wood block and noted in relation to the time that had passed since the placement of the block. The time elapsed was consistent across all samples.

All results were recorded and compiled into a chart allowing comparisons to be made. Results showed that Bona Silane Adhesives cured faster and displayed up to 150% greater green grab and early tensile strength than competitor brands. For full test results please contact Bona Australia Head office on 03 9543 4399.

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