I am renovating. The skirting boards / architraves have badly chipped enamel over varnish. I want to end up with Dulux Super Enamel topcoat on them. I am not clear on how to prep the varnished / painted timber. At the moment: scrap paint off with heat gun, sand the varnish, Dulux Sealer Binder, then 1Step oil, and Dulux Super Enamel. Is this the best approach?? Would Dulux Maximum Strength Adhesion (water based) bind better?