Chemical dip vs Media Blasting

[Ryan Adkins]

Hi,

What is the best way to prep a 1978 911SC from metal? Chemical dip vs media blasting?

[962porsche]

there is no best way!
the way you would strip a cars finish depends on why the car needs to be striped.
dipping a car you will be removing every bit of primers and paint from both the inner sides of the panels as well as the outer panels. this could be a problem trying to get rust protection back on the inner sides of the panels you can't get to.

blasting you will end up with media in every nook and cranny making it a PITA to clean it all out. if you don't clean it all out it will hold moisture and like having no metal protection left from dipping will cause rusting later on down the road.

machine stripping with a DA. this could be a time consuming task.

chemical stripping with paint stripper.
this is a messy job and also time consuming.

the questions are why does the car need stripping? does the hole car need to be stripped or just a few panels.
all to often people will strip a hole car needlessly thinking it's the best thing to do.

[mepstein]

I’m chemically dipping but also getting it e-coated so everything is coated like new cars. It’s a 67 so the heater tubes are steel. Later tubes are paper and disintegrate in the chemicals. Best way is to dip, do metalwork, dip and then e-coat. It sure isn’t the least expensive way.

[Ryan Adkins]

The reason for the stripping was due to the car being in a fire as seen in the image below.

[962porsche]

in your case if we were doing that job it would be a dip.the reason why is everything was burned to a crisp also between the panels and is now rusting. you couldn't blast the areas that would need to be addressed. all the rubber and plastic has to be removed and replaced so your doing that anyways.

blasting the inside of a car isn't the best idea to do . the media gets into everything and is total hell to clean.

there is NO 1 best way to strip a cars finish. they all have good and bad about them.

it's common for a car that is dipped and e coats to still end up with debris to be left in places between the panels. like in the drawing of the rocker but this is the case also with all areas of the car like say roof structor. the down side is some areas do not have drainage to let the debris exit from and even with drainage debris still can be trapped and just be e coated back over.

[Ryan Adkins]

Thank you @962porsche, I will plan on dipping the car at this point then. Do you have any recommendations on thinks to ask when finding a place to do the dip?

[Ryan Adkins]

Once I chemical dip the car. Do I first use epoxy primer then prime and paint?

[Ryan Adkins]

I’ve found the place to chemically dip the car in Indianapolis, IN. Pro Strip Indy has experience with dipping 911’s.

[mepstein]

The problem with chemical dipping is it removes all the paint and primer from between the welds and all the spots that a paint gun won’t reach. That’s why the dip into e-coat is so important. Granted, if you live in a low humidity area, it won’t rust as quickly but bare metal isn’t the solution for long term success.

[Ryan Adkins]

@mepstein Who are you looking into to e-coat your car?

[962porsche]

Originally Posted by Ryan Adkins

Thank you @962porsche, I will plan on dipping the car at this point then. Do you have any recommendations on thinks to ask when finding a place to do the dip?

some dipping places will also do the E-coating .
others that will just do the dip stripping do not also do e-coating so it could be left up to you or they will sublet the e-coating out.
we did have a problem with a place many years ago that stripped a few of our cars for us.
what happened to one car was they went thru the 3 steps to strip the car. acid , alkaline and then rust-inhibitor. the problem is the rust inhibitor only works for a short time to prevent flash rust. the place they sublet the e-coating out to took 6 weeks to e-coat the car. by the time the car got dipped in e-coat it started to flash rust and was coated over it.
when we started working on the car and sanded thru the E-coat we saw rust under it.
this was a big problem. what we got was the stripping place and the e-coating place pointing there fingers at each other. turned out it took almost 3 weeks for the stripping CO. to get the car over to the coating place and then took the coating place another 3 plus weeks to get the job in and coat it.
part of the problem was the C0. they used to ship the cars from the stripper to the e-coating place. I was told by the coating business the load of things that came to them from the stripper Co. came on a open trailer. the stripping place said it was BS! I feel it was true????

needless to say it was a total do over and we ended up footing much of the bill again.

after that mess we would go get the car right away and get it right to the E-coating business. we would make dam sure the car would get coated right away. I hate to say it but at times I know we were a PITA making many calls to both the stripping place and the coating place to coordinate everything. then sending one of our employees with our trailer to bring the cars 150 from one place to the other.

[Ryan Adkins]

@962porsche would you then recommend that I use a shop that does both the dipping and e-coating? Is there any place that you would recommend? Also, will it be an issue with paint being able to stick to the body panels due to the fire?

[Dpmulvan]

Do not dip a 911 chassis you will ruin it. These chassis are built with folded metal, there is adhesive in several places for instance under the rear window and several others places where seams meet. Porsche also used a type of fabric or tape which kept metal on metal from rusting ( in the roof).
I guarantee your car will prematurely rust . Why do you think top Porsche shops strip cars by hand??

[962porsche]

I don't know of any places down south.
it's not a problem or shouldn't be if the place doesn't do both. the places we used don't do both so we took it upon our selves to coordinate everything making dam sure the things we needed stripped and coated was done in a timely manner.
the fire shouldn't effect anything at all. we have had a few old 911's /912's and 356's that had engine fires dipped with no problems.
on some cars the heat of the fire will buckle and warp the panel/s beyond repairing.

[Ryan Adkins]

@962porsche thank you for you help. Does the car need to be e-coated or will epoxy primer work? I have already talked to a shop and they recommended to seam weld the car after the dip.

[Dpmulvan]

E coated is epoxy coated.

[Ryan Adkins]

@Dpmulvan Thank you, I didn’t know that. I guess I should clarify, is it ok to just spray epoxy primer vs the e-coating process?

[Dpmulvan]

Originally Posted by Ryan Adkins

@Dpmulvan Thank you, I didn’t know that. I guess I should clarify, is it ok to just spray epoxy primer vs the e-coating process?

E coating process = spraying epoxy. I think your confusing e coating with electro painting or static.
When he says e coat he means epoxy paint. Yes you wanna spray epoxy over bare metal ASAP especially if you live in a humid location.

[Ryan Adkins]

@Dpmulvan I though e-coating was a dipping procedure that uses an electric charge to make it stick to the body like they do a the factory?

[Dpmulvan]

Actually now that I have read the entire thread, 962 means the process after the dip. I think they dip into tank with charged paint particles, it’s suppose to get into all the areas stripped by the acid.
Sorry about that