I am in the process of blocking out the '72 E.C. and, as I am sure everyone is aware of, there are hardly any FLAT areas on these cars... most are concave and convex.. I am guide coating and doing everything by the book but my question is...what is the best way to sand areas that are semi-flat...like the doors and the center rear quarter panels..etc.
Is it best to sand on a criss-cross pattern? Or straight back and forth and up and down?
I am using a ridged long board and also a flexible long board. On the inside curves I use a rolled up magazine that is taped up all along the length...
Thanks,
7T2SS

Look at the side of the car and picture a big X, the two lines that make up the x are basically the directions you should move the block. Moving the block or sanding board in a parallel motion with the length of the car will create flat spots on convex areas and sanding grooves from the block's edges in the concave areas. Use as long of strokes as possible and carry the block over panel openings if the panel alignment is good. I usually start with 180 to get the correct shape and then move to finer grits. You can also apply guide coat again after each grit to make sure all the sandscratches from the previous step are removed. Hope I made sense. I wouldn't use a magazine if you're looking for really good results, plastic or pvc tubing works well, just use the x pattern within the concave areas. My final grit is 600 wet followed by a good rubdown with three stacked grey scotchbrite pads, let the paint flow!

Use black laquer as a guide coat. a real light coat. This is to tell you where the high and lows are. The key is knowing when to start building up the lows. This will happen several times. Get several sizes of sanding blocks, boards, paint sticks, radiator/heater hoses, plastic drinking cups, anything, but no bare hands. Use nice long strokes, criss-crossing. I usually sand from the center to the edge of the panel. Get a quality natural sponge for water control. When you get at the final stages. wet the whole car to simulate a shiny finish. Take your time, it will be worth it. Besides it a warm up for color sanding.

Thanks guys..for the info.
I will drop the magazine sanding block and take up the advice of the pvc pipe on the concave areas.