I polished my car about 2 monthes ago and washed it about 4-5x again. Now in the sun I can already see scratches again which seem to be coming from washing. But the scratches are only on the front/back bumper and not on the whole car. Why is it like this? Does it come from the softer material?

 

It may be as simple as more 'grit' being on those two surfaces than the rest of your vehicle.

Both surfaces are closest to the ground, along with the sides between your wheels, but unlike the sides, the front is being smacked all the time head on by road grit and the rear is getting it through the updraft.

If you don't want to wax the entire car again, you can always do touch up waxing on these two surfaces between full vehicle waxes.

Just a thought....

 

i think you're just dragging sand while you wipe, especially the rear.

you have to use a lot of detailer spray, make one swipe on the terry,
turn over and dry. don't use the first side of the terry and fold.

 

The bumpers seem to be a lot easier to scratch for me too. Probably a combination of more dirt and softer material

 

I've noticed the same thing on my rear bumper. Now when I was it gets lots of rinsing & suds. That seems to have taken care of the dirt magnet, I mean bumper.