Media Blasting the Body

356 Porsche-related discussions and questions.
Post Reply
Message
Author
Greg Spreeman
356 Fan
Posts: 616
Joined: Fri Mar 14, 2008 9:47 pm
Location: South Orange NJ

Media Blasting the Body

#1 Post by Greg Spreeman » Mon Jan 15, 2018 12:22 am

I think it makes sense to media blast, maybe with soda, the entire car I'm working on. Looks like there is tons of pitting and God knows what else under the black coat of paint the PO sprayed on. So, here goes. Is soda the best medium to get the body down to bare metal? How do shops protect the metal from flash rusting after they blast the car? Anybody know of shops around Newark NJ that does blasting? What other questions should I have asked?
Greg Spreeman
1965 356SC Coupe
1964 356C Sunroof Coupe

User avatar
jim nelson
356 Fan
Posts: 2005
Joined: Wed Mar 26, 2008 2:18 pm
Location: SoCal
Contact:

Re: Media Blasting the Body

#2 Post by jim nelson » Mon Jan 15, 2018 2:21 pm

When we had our '60 Cab blasted, it was with walnut shells, and we took it straight from the blaster to our painter, who put a protective coat of primer (which kind, I don't know) on it.
s-l1600.jpg
IMG_0969.jpg

User avatar
Ben Wainscott
356 Fan
Posts: 139
Joined: Sat Mar 29, 2008 12:30 pm
Location: Southern California

Re: Media Blasting the Body

#3 Post by Ben Wainscott » Tue Jan 16, 2018 9:20 pm

Greg, not sure about soda. Recall discussion from one 356 painter about how a coating was left with a soda blast that caused paint problems down the road. The only thing I know about painting comes out of a rattle can, so I'm only providing a caution that I have heard about. Others may have more experience/details.

Ben
Ben Wainscott
65 SC S/R coupe
89 911 Carrera
63 Vespa 150
80 Vespa P200e

Greg Spreeman
356 Fan
Posts: 616
Joined: Fri Mar 14, 2008 9:47 pm
Location: South Orange NJ

Re: Media Blasting the Body

#4 Post by Greg Spreeman » Wed Jan 17, 2018 12:03 am

Thanks Ben. I'm new as well. One thing I keep hearing is that soda is water soluable and therefore a bit easier to get out of everywhere. When I take a look at the pics above, I'm thinking walnut is the way to go. Problem is, here in NJ, the closest shop is some 30 miles away so I'll have to get a tow truck down and then a tow truck back. Not a huge expense but, those costs start adding up really quickly.
Greg Spreeman
1965 356SC Coupe
1964 356C Sunroof Coupe

User avatar
Greg Bryan
356Talk Moderator
Posts: 2205
Joined: Sat Oct 04, 2008 1:05 pm
Tag: Be Nice!
Location: San Pedro, CA 90732

Re: Media Blasting the Body

#5 Post by Greg Bryan » Wed Jan 17, 2018 12:27 am

I think that soda is not aggressive enough for a complete strip job. Soda will remove paint but little else, leaving rust.
As Jim says above, walnut shells won't remove metal but will effectively strip the body to its basic elements.
Greg Bryan
356Talk Moderator

Martin Benade
356 Fan
Posts: 3536
Joined: Wed Nov 23, 2011 10:52 am
Location: Cleveland, Ohio

Re: Media Blasting the Body

#6 Post by Martin Benade » Wed Jan 17, 2018 8:44 am

Does walnut remove rust, or is it also gentle?

User avatar
jim nelson
356 Fan
Posts: 2005
Joined: Wed Mar 26, 2008 2:18 pm
Location: SoCal
Contact:

Re: Media Blasting the Body

#7 Post by jim nelson » Wed Jan 17, 2018 11:50 am

Martin Benade wrote:Does walnut remove rust, or is it also gentle?
We found that walnut shells were pretty effective at rust removal, though most of what we had was surface rust after sitting for 20 years. The car pictured in my first response came out of the blaster looking like this:
IMG_0958-1.JPG
IMG_0958-1.JPG (64.63 KiB) Viewed 529 times
IMG_0959-1.JPG
IMG_0959-1.JPG (48.3 KiB) Viewed 529 times
better pictures on the "60 Cab project" thread in the projects forum...

Robert Vaughan
356 Fan
Posts: 326
Joined: Fri Dec 03, 2010 7:42 am

Re: Media Blasting the Body

#8 Post by Robert Vaughan » Wed Jan 17, 2018 6:47 pm

Greg,
If you received a body that looked like the one in Mr. Nelson's photos above, with no paint on it anywhere, and you were still in north jersey, with summer humidity, you would really have to scramble to get some sort of primer on it to prevent flash rusting. Otherwise the flash rusting would bedevil you. It is hard enough just keeping up with a 5 or 10 square feet of exposed steel surface.

User avatar
Bill Sargent
356 Fan
Posts: 879
Joined: Thu Apr 10, 2008 11:03 am
Location: Beijing, PRC

Re: Media Blasting the Body

#9 Post by Bill Sargent » Wed Jan 17, 2018 10:53 pm

I have personally had two 356s soda blasted and can confirm that soda will not remove rust. It is excellent at removing paint and even light grease buildup. Also good to strip something like an engine lid that you do not want hidden media later making its way into a carb. To remove rust you will need something more aggressive than soda. Once the soda blasting is complete it leaves a basic (positive Ph) film on the metal that must be removed/neutralized before painting. I used a pure white vinegar wash followed by a water power wash followed by more white vinegar and another water power wash. Power wash focused on seams both times. As others have noted, the bare metal flash rusts during the neutralizing process. I then used some of the commercial metal phosphating solution prior to paint prep. After all that I did see a little soda fuzz after a few months from a seam around the interior rear seats. No other problems.

To remove rust on the pan and other non outer body panels I used crushed glass. Which worked well. We did not use it on the inside of outer body panels, like fenders, out of concern for possible warping.
Regards,

Bill Sargent
#151489 59A Cab
#159176 64C Cab
60 VW Singlecab
73 911 T
904 clone in the works

User avatar
John Brooks
356 Fan
Posts: 734
Joined: Tue Jul 08, 2008 11:50 am
Location: Whidbey Island WA.
Contact:

Re: Media Blasting the Body

#10 Post by John Brooks » Thu Jan 18, 2018 12:23 am

I saw a plastic material at a aging aircraft sustainability conference last year. It was small triangular shaped grain that looked like walnut shells, but softer. Was supposed to be superior to sand, glass, and copper oxide for paint and corrosion removal. It removed paint and corrosion but would not stretch or deform the metal by media impacts. It looked like a deburring vibration machine media but tiny.

The samples looked good, I do not know the trade name or manufacture, here is a start.

http://www.kramerindustriesonline.com/b ... -media.htm
John Brooks

62 Roadster
66 912
getting pushed around in porsches since 1965

Post Reply