Altro W165 ‘tape primer’ is used in conjunction with double-sided tape and should be applied in three locations to the substrate with a 50mm paint brush. The primer ‘lines’ should correspond to the double sided tapes which will subsequently be fitted on the reverse side of the sheet - at the top, the middle (normally just below datum height) and at the bottom of the sheet. The double sided tapes hold the sheet firmly to the substrate whilst the AltroFix adhesive cures. Allow the ‘tape primer’ to dry to a tacky finish, (approximately 10 minutes). Note: The tape primer remains permanently tacky and never dries out totally.