BS EN ISO 7784-1:2016 pdf free
BS EN ISO 7784-1:2016 pdf free.Paints and varnishes一Determination of resistance to abrasion
Condition the strips of abrasive paper (5.2.2) [and, if necessary, the adhesive tape (see 5.2.2, Note 1)] in accordance with 6.3 and adhere them to the circumference of the rubber wheels (5.2.1) without any gaps or overlapping. Subsequently, store the prepared abrasive wheels under the climatic conditions in accordance with 6.3 until using them during the test.
It is recommended that the strips of abrasive paper be cut at an angle of 45° and joined respectively when adhering (see Figure 3).
Weigh the test specimen to 0,1 mg using the balance (5.4) and mount it to the turntable of the apparatus.
Attach the abrasive wheels, which have been prepared in accordance with 7.2, to the arms of the apparatus and lower onto the coating.
Load the abrasive wheels, if necessary, in accordance with the agreed test load using an additional weight each (5.3).
Calibrate the counter to the agreed number of cycles (turns), turn on the suction device, and start the rotation of the turntable.
The abrasive wheels can become very smooth when taking up coating material so that they lose their abrasive effect and, consequently, stop rotating (and begin to block). In this case, the test shall be interrupted and the abrasive wheels shall be covered with new abrasive paper in accordance with 7.2.
In order to avoid blocking, it can be appropriate to agree on a lower number of cycles.
In case of wear through of the coating down to the substrate or down to a subjacent coating, a lower number of cycles shall be agreed.
For each of the three test specimens, calculate the loss in mass of the coating as difference of the masses of the test specimen in accordance with 7.5.1 and 7.5.5, in milligrams. Calculate the mean value of the losses in mass of the three test specimens.
As test result, report the mean value of the losses in mass in accordance with 8.1 and the three single values to the nearest 1 mg.BS EN ISO 7784-1 pdf free download.
