In this Short video, I discuss how to remove old undercoating from your Vintage VW.
We are in the middle of doing this procedure on a bug right now. If you are making a show car, no one likes the site of undercoating. Plus removing the old undercoating will expose rust areas you normally would not see since it is covered by the rubberized stuff.
If you are making a daily driver, you might not be so concerned about removing the undercoating. Whenever I am restoring a car, daily driver or not, I like to remove the old undercoating to see what lingers underneath. Because you never know how long that undercoating has been there. That stuff traps moisture, so it is good to make the repairs before painting.
I also found this video recently using a “Needle Scaler”