Method of replacing a windshield utilizing a knife for removing scalant

A method of preparing an auto windshield opening for receiving in seated relation therein a replacement windshield for a defective windshield, said defective windshield being of a type of a generally rectangular shape having a peripheral edge in a clearance position inwardly of a wall bounding said windshield opening defining a gap therebetween and having cured urethane bonding said defective windshield peripheral edge to said gap-bounding windshield opening wall, said auto windshield preparation method comprising a first step of inserting two blades in adjacent position to each other with a selected nominal clearance therebetween to extend in cutting relation from a blade holder, a second step of inserting said blades incident to a cutting stroke into said cured urethane with a first blade adjacent said wall bounding said opening and a second adjacent blade located inwardly thereof so as to define an opening into said clearance of said blades in facing relation to a directional cutting stroke of said blades, a third step of urging said blades through a cutting stroke causing said first blade to move along a straight path due to the effect of said adjacent position of said opening-bounding wall and simultaneously causing said second blade to move along a wavy path alternately away from and towards said first blade due to the effect of varying resistance to cutting of said cured urethane, a fourth step of engaging urethane severed by said blades entering into said clearance between said blades incident to transverse closing movement of said second blade towards said first blade so that a continued cutting stroke movement pulls free said engaged urethane, and repeating the second, third and fourth steps adjacent said defective windshield peripheral edge, whereby said urethane is removed from said gap freeing said defective windshield and facilitating the seating in said auto windshield opening of said replacement windshield.