Blue Demon Triple Play

This very thin layer of aluminum oxide is what must be removed. When you puncture this layer it breaks up into a fine powder and floats to the surface of the puddle. You can actually see it appear on the surface. Draw the abrading tool through the puddle several times to remove oxides and promote fusion with the base metal. A few strokes are usually enough-.004 to .005 deep gives maximum strength. Get rid of the oxides' barrier by going down through the molten coating and abrading the oxides away. A thin layer of insoluble oxide begins to form on the surface even before you lay the brush down.

As the base metal is heated, oxides form even more quickly but become stretched under tension. The oxide must be removed or penetration will not occur. Localizing of heat techniques can also be utilized to improve the shape of the fillets.