Using a more rigid sanding block does not equal better results. As a matter of fact, it's not very often at all a very rigid sanding block is needed. How do you decide what to use though?
There isn't an exact way to figure out which sanding block to use, and I'm sure it might vary from person to person. A general idea though, is that the sanding block should help you make the shape you are trying to make correct. Imagine a bowling ball, and you had to body work it. You could grab a solid sanding block, and start trying to block it and get it round. I'm sure it's possible, but it would be a nightmare. It would be completely up to how you're moving the sanding block to create the right shape. Or, you could grab a flexible sanding block; one that forms to the shape of the bowling ball with a slight amount of pressure. Using this block would be far easier to sanding the round shape back into it. Of course, you need to sand it correctly, but the sanding block will also help you tremendously by flexing to a round shape.
The above idea, of body working a bowling ball, can be translated into any car. The sanding block should be able to flex to conform to your desired shape. Sometimes, there is hardly any shape, and a rigid block might be necessary. Most times, there is some shape and the block will need to flex.
- It should take a small amount of pressure for the sanding block to take the right shape.
- Too rigid and it will only sand in the center, and be mostly useless.
- Too flexible isn't good either, doing body work with a noodle won't do much.
- It should feel right. Part of the magic of True Blox is just the simple nature of the material. It can flex, and always wants to return to it's original shape; straight. This means when it bends, it bends in natural arch. Let the help you.
- Up and Down. A sanding block should always be able to flex, even if it is slightly. Even a vehicle that is completely flat more than likely has some shape to it vertically. (yes there are exceptions) The block flexing just slightly will help make sure the panels are 'straight' up and down too. This part of body work is very important and often over looked.
- Do not confuse a hard sanding surface, like acrylic, with flexibility. The hard backing surface is essential to great body work. That doesn't mean the blocks can't bend and create and shape that is needed.
Look at your sandpaper!! It will tell you a lot! For the most part, the sanding dust should cover the entire length of the block. If it is concentrated in the center of the block, it is too rigid, use something more flexible.
Notice all the cars below have very different shapes. Even the flattest of them required slightly flexible blocks. Let the blocks help you do better work!