Restoring a '78 911 sc and have questions about soda blasting

[Rudycoop]

Hello all, I would like to start by saying thank you to this forum for providing me with so much insight on body/paint work. I have been reading tons about soda and decided to blast my car with it. I built a booth in my garage with an exhaust fan and intake. I am wearing a dual cartridge 3m respirator and haven't had any issues with my respiratory system. I never feel right after sanding even with respirators.

My car was originally guards red, then resprayed red again, then resprayed petrol blue i believe. I plan on respraying it guards red w Glasurit 22 if I can get it.

I have managed to get rid of all the blue which was a primer/base/clear and all the second round of red/primer. Some areas had the respray over bondo/bare metal and some areas they left the original finish. If I have no rust can I prep the original finish to paint over? Some areas have cracking all the way through and I have no choice to go all the way down, but why not leave at least the original primer where I can? Does the soda have any effect on the situation? I don't mind having to clean and sand it after. I have a few set of extra hands to help me with that side of things. I'd love opinions. I'd also love to save some time and $$ on media. So many coats of paint on this thing!


This is when I was in the process of building the tent in my garage.

[962porsche]

soda blasting is great but we would never do a steel bodied car with it .
only aluminum and composite bodied cars .

[Rudycoop]

Originally Posted by 962porsche

soda blasting is great but we would never do a steel bodied car with it .
only aluminum and composite bodied cars .

So do I have to go to bare metal or can I leave paint after soda blasting? That is really my question. I have read your reasons why you don't use it. I don't have any rust and I have 3 layers of paint. I don't mind having to sand and scrub after. I can do it all at home and wash it down the drain in my floor. I plan on being overly obsessive with the cleaning process. I appreciate any help.

[962porsche]

if it were me I would just strip every thing down to bare .
there is no real reason to leave material in the car at this point that will or could give you headaches later on .
the other reason we like to use plastic media is the clean up and prep work .
with soda it will get into the cracks and crevices like all media will but because it holds moisture more the plastic many years from now it will be places that will rust out .
many people stated the problems with adhesion after soda blasting . this is just not all that true ! they have problems because they did not clean the then sand the panels 1st . soda leaves to fine/smooth of a substrate for undercoats to stick to so you have to sand with 180 grit paper after you do your blasting . this should be done always after you blast with any media . the bad with soda is the residue left after you blast . this needs to be clean off before you do your sanding . sanding will not remove it so you have to clean it off with metal wash . you don't want a metal wash /cleaner that will protect the metal you want one that just cleans bare metal for removing the residue .

[Rudycoop]

Thanks for the awesome response. I pretty much expected that. I just never saw so many layers of paint on a car! I have it all apart and read that it's much easier to clean up that way. I plan on using all the right stuff. My booth has a drain in the floor. I wish I had access to plastic, but soda was about all I could do other than sand.

[E Sully]

While 962porsche is at the top of the field, from my research I would not use Soda. Clean up and prep would be more extensive. Paint manufacturers advise against it's use from what I've read.
http://www.crankshaftcoalition.com/wiki/Soda_blasting

[Rudycoop]

Originally Posted by E Sully

While 962porsche is at the top of the field, from my research I would not use Soda. Clean up and prep would be more extensive. Paint manufacturers advise against it's use from what I've read.
http://www.crankshaftcoalition.com/wiki/Soda_blasting

I have also done tons of research. BASF doesn't have a negative stance against it and I plan on using their products. The prep isn't that terrible. It's just an extra step. I have talked to so many people that love soda. You always find the negative side because people love to complain. The car is tiny and in a million pieces. It's going to be simple to clean and sand at the end.

I don't wish to deal with anything toxic and I couldn't get my hands on plastic. Sanding is an awful dirty process. Right or wrong I will continue to post my results and show my experience with painting after...

[962porsche]

your 100% right BASF has noting against soda blasting simply because it has to do with the way you prep the substrate . you use it on aluminum and composite and prep and paint over that with out problems if it's properly prepped .
yes many have things against soda blasting . I for one don't but also it's not my 1st pick for steel panels as again we use it but for the materials I stated .
the clean up of the soda off the steel is not all to ez in some ways because of the residue left from the soda . di not try and sand it off you only push it into the sand scratches and them that's were the adhesion problem comes into play .
the problem is not really the soda it's in people being easy with prep . again what I don't like with steel is any soda will hold moisture . never think you will get all the soda out for the little areas of the car . it will get into places like the inner rockers and you will never get it out from there . you will not have the same problems as we do with moisture in CL. as we do with it in CT. but it will not dough still hold moisture .
just be dam sure you clean the substrate real good before you start your sanding .

[Rudycoop]

Originally Posted by 962porsche

your 100% right BASF has noting against soda blasting simply because it has to do with the way you prep the substrate . you use it on aluminum and composite and prep and paint over that with out problems if it's properly prepped .
yes many have things against soda blasting . I for one don't but also it's not my 1st pick for steel panels as again we use it but for the materials I stated .
the clean up of the soda off the steel is not all to ez in some ways because of the residue left from the soda . di not try and sand it off you only push it into the sand scratches and them that's were the adhesion problem comes into play .
the problem is not really the soda it's in people being easy with prep . again what I don't like with steel is any soda will hold moisture . never think you will get all the soda out for the little areas of the car . it will get into places like the inner rockers and you will never get it out from there . you will not have the same problems as we do with moisture in CL. as we do with it in CT. but it will not dough still hold moisture .
just be dam sure you clean the substrate real good before you start your sanding .

Thanks again for the awesome advice. I meant to mention my climate as a factor earlier. It's cool and dry here. I haven't had any moisture issues.

I have a power washer and have read purple power in a tank sprayer works well. I know it also leaves a residue. What cleaning agent would you use?