While electrical power (675 W), electrodes gap (0.25 mm) and total gas flow rate (40 standard liters per minute, slpm) were maintained constant throughout the experiments, gas composition and exposure times were changed. Two different gas compositions were tested: 100% He and 99% He+1% O2. The exposure time, regulated by controlling the grounded electrode velocity, was set at 20 and 30s. After the plasma treatment each sample was immediately immersed into the finishing solution with an elapsed time less than 5s, carefully imbibed and then submitted to the pad-dry-cure process.
A summary of the plasma variables is given in Table 1.