[T3] Undervoat question

[David Sanderson]

Hi All
I have been working on my fenders, repairing where necessary and   
getting them ready for paint.

http://www.thesamba.com/vw/forum/viewtopic.php?p=5648228#5648228

One of the fenders has some undercoat. What is curious is that some of  
the undercoat obviously did not stick well because I was able to  
simply scrape it away and it came off in flat sections. On other  
spots, however, it was stuck firmly and I had to use a heat gun to  
soften it before I could scrape it off. I am wondering what the  
consensus is on spraying undercoat on these cars. I live in the  
Pacific Northwest where we have lots of rain. Also, I wondered why the  
stuff did not stick so well in some spots. Was undercoat something the  
factory sprayed on or would it have been done by the dealer?

Thanks in advance.

Dave
1977 911S
1965 Sunroof Notch
http://www.sandersonmotorsports.com/
Notch build here: http://www.thesamba.com/vw/forum/viewtopic.php?p=5600139&highlight=#5600139