[jr_ss]

A rigid sanding block does not flex. I should've specified what I used as to protect people from themselves. A block of steel machined flat with sandpaper adhered to it doesn't flex.
However, I've never had a headgasket issue with my method. Everything should be done in moderation. I don't expect one(atleast one with common sense) to go out with a flimsy knock down splatter sanding block.