Pros and Cons of the Paint Stripping Processes

[stevep516]

I've started the process of restoring my 1940 Packard Conv. Sedan and I wanted to get some input regarding the process of stripping the metal in prep for painting. I've read through a lot of the old posts regarding the subject matter and there seems to  be pros and cons to all types, from sand blasting to metal stripping. I am interested to hear if the latest technology of "dustless blasting" has any merit.

 

I'd be interested to hear what process most folks are utilizing these days......... Chemical Stripping , soda blasting, Dry Ice, etc. What are the drawbacks to each process.

 

Thanks for the input!  

[Taylormade]

Chemical stripping - does a great job but make sure the chemicals are completely removed from the body after stripping.  They can hid in recesses and leech out after a period of time and ruin your new paint job.  Expensive and hard to find a shopthat does it nearby.

 

Blasting - also does a good job, but find someone who knows what they are doing.  Too aggressive with the blaster and your sheet metal will warp or distort.  Also must be thoroughly cleaned after blasting.  Sand blowing out of recesses during the painting process can be a nightmare.  Easier to find a shop that does it.  Still quite expensive.  I'm no expert on soda,dry ice and walnut blasting.  I've heard they take off paint, but not rust.  Others with experience will chime in, I'm sure.

 

I've had friends that have had good luck with aircraft paint stripper in a DIY situation.  Messy and a rough on the skin, but it works.  Other just got out their DAs and went to work sanding off the paint.  Also messy, but it works if you don't get over aggressive and start removing too much metal.  In any situation, if you do it yourself, it won't be a lot of fun.

[Bhigdog]

What he says regards blasting. Also chem dip removes everything including the factory seams sealant. I've used paint remover and find it tedious and messy and you still have to go back over it with abrasive paper. I just bite the bullet and use my DA in non orbital mode with 36 grit paper and just go at it. It's as fast, if not faster than the other methods. Best to do it outdoors. For the rusty pitted spots I VERY CAREFULLY sand blast at an oblique angle with reduced air pressure. Never had a warping problem. If you take your body to a sand blast guy that's used to working on farm equipment and steel girders he will likely ruin your sheet metal......................Bob

[F&J]

I do some crash work on 35-45 year old "collector" cars that have had several thick acrylic enamel repaints piled on, as well as some body filler under the paint layers.

 

On these, the layers are too thick for blasting unless you have a huge compressor, large nozzle, and sharp quartz sand....and skills needed as to lower pressures and attack angle of sand.

 

...  Because of the fillers and multiple layers, chemical stripping would take too long.

 

DA or air grinder takes too long on multiple thick layers with fillers, grinding can also gouge the surface, and either makes too much dust.

 

I'm doing one fender today with a propane torch and 1" scraper, then I use DA to finish strip the residue.

 

Each car is different, as if it were a single thin layer of OEM paint, and very thin OEM primer, I would be using just the DA.

 

.

[edinmass]

We use aircraft paint stripper, nasty stuff, works good, then we dust it with a sandblaster. You must be careful with any media blasting. Dipping is ok if it's close by and affordable. Neat car. Enjoy!

[Larry Schramm]

I second the comment on chemical dip stripping.  It can get in the seams and leak out over times.  You would need to power wash all seams extremely well to be sure the stripping agent is out of the seams.  The chemical strip takes out ever bit of rust, bondo, etc..

 

Here in Detroit the chemical stripper runs the parts through an oven to back out all of the grease, etc before dipping the parts.

 

A friend of mine just had his doors run through the oven and then media blasted.  He (and I  agree) that he got the best of both worlds.

[stevep516]

Thanks guys, for the input.........I think the best option for me is going to be the chemical strip. There is a co in PA. called MEC Chemical that has been recommended to me. I spoke with them and after the final process, the parts  are sprayed with a water base rust inhibitor that will need be  washed off. Other than the long distance drive, it sounds like the direction that I want to go.

Also, I'm not going to pull the body off the frame, so I'm looking  into the option of blasting the underside with dry ice. 

 

Thanks again for  the sage advice..............

 

 

[Restorer32]

In our shop we will not paint parts that have been chemically stripped by dipping. Too great a chance of chemical residue coming out of a seam or hidden area somewhere down the road and causing problems. We guarantee our work but are not really interested in guaranteeing the work of the stripper also. We strip everything by hand followed by a rotary sander. For highly formed areas like door jambs or raised fender edges we sandblast using very fine sand. I doubt it ends up costing the customer any more, possibly less, than dipping.

[R Walling]

 I prefer paint striper, I do one panel at a time.

 I have found that most people do not use enough stripper the first time and take it off too soon.

 Apply a thick layer, do not brush it it, cover it with plastic film and let it work.

 Use a plastic scraper and a SS scrubbing pad to loosen any tough spots and let it sit again if necessary.

 

 Sometimes it may take a second coat.

 Thoroughly wash it off with hot water and blow it off with an air hose and a towel.

Finish it up with a DA and a sandblaster for the hard to get spots. (For fiberglass be very carefull with the sandblaster and use sparingly, hand sanding is prefered)

 

Using thin layers will only cause you to use more stripper than a thick layer. Buy it by the gallon, remember, the object is to remove paint, not to see how little you can use. 

[28 Chrysler]

When I use paint stripper I tape over body gaps and trim holes, then DA what is left.

[Restorer32]

Had a customer years ago who sent his '33 Packard Conv body (minus the wood of course) out to be dipped. He did not realize that the very complicated windshield posts were die cast. They basically dissolved in the tank. We had to fabricate new pieces. That is when we decided to stay away from dipping. The chemicals used are strong bases, basically lye and water. Lye and aluminum or die cast just aren't very friendly toward each other.

[joe_padavano]

23 minutes ago, Restorer32 said:

Had a customer years ago who sent his '33 Packard Conv body (minus the wood of course) out to be dipped. He did not realize that the very complicated windshield posts were die cast. They basically dissolved in the tank. We had to fabricate new pieces. That is when we decided to stay away from dipping. The chemicals used are strong bases, basically lye and water. Lye and aluminum or die cast just aren't very friendly toward each other.

 

This is no different than putting an aluminum engine block in a hot tank.  Improper use of a process is not a reason to condemn the process for all uses.  Yes, improper post-dip removal of the stripping agent can bleed through paint.  Yes, it requires diligent cleaning with the proper neutralizing agents.  Same thing with soda blasting.  Many people condemn soda due to trapped blast soda bleeding through paint, but proper cleaning with the right materials solves this problem.  I'm not suggesting that any one method is "the best", but having an arsenal of methods available for different situations is always preferred. One just needs to follow through on proper techniques and methods.

[Willie Wurke]

A 4 inch grinder with a stripper wheel from Walmart does pretty good.