Removing Rust and Paint By Harold Pace/autoMedia.com
Sandblasting or Chemical Dipping - Which is Better?
Before you can begin restoring an older vehicle, you’ll need to strip off all the old layers of paint and rust from the body and frame. Sure, you can grind away with wire brushes and sandpaper, but these methods take forever and make a huge mess. Better options consist of either dipping or blasting.
Sandblasting For smaller parts, sandblasting is a simpler way to go, but removing thick rust from large body panels and frame members takes a lot of time, air volume and media. So sometimes it’s better to take your big parts to a pro with the equipment to do the job, and the safety gear to keep toxic material out of the operator’s lungs.
Sandblasting looks deceptively simple, but if not done correctly, it can damage thin body panels. So before you drop off your precious metal, make sure the shop is familiar with automobile restoration work
Note that industrial sandblasting operations typically use too much pressure and can concentrate on one area for too long, leading to overheating of the metal and warping. They also need to choose an appropriate media for the metal, as special “softer” media can be used to clean aluminum and even fiberglass without damage. Too-aggressive media can also lead to a pitted surface that will require hours of filling and sanding for a neat appearance. Shops that specialize in auto bodywork won’t be reluctant to show you examples of jobs they have done, and provide references.
On the other hand, there’s chemical dipping. This approach once had a bad reputation that it does not necessarily deserve today. Early dipping operations used acids that removed paint and filler, but not always rust. Parts also had to be carefully treated to prevent acid from being trapped in body crevices, only to seep out down the road and destroy a fresh paint job. Today’s shops use environmentally friendly formulas that clean off rust and coatings, and that can be completely neutralized afterwards. These chemicals also have low toxicity and are safer to use.
So which is better? It depends on the project. Blasting tends to be less expensive, so it’s a good choice for rusty frames and heavier metal parts. Dipping is better at getting into interior panels, such as on unibody cars, and won’t warp or distort thin sheet metal panels.
Even more important than choosing between blasting and dipping is finding a shop that understands what you need done and has the experience to do the job. After all, since rust never sleeps, you need an operator that’s alert to your getting your restoration project off to the right start.
This classic T-Bird doesn’t look that bad at first glance, but under that glopped-on pink paint was a bodyperson’s nightmare. The restoration shop brought it to a metal cleaning service in Texas to have the layers of crud and rust stripped away.
After dipping, it became obvious that the nose had been wrecked and crudely patched, and a ham-fisted bodyman attacked the peaked fender tops with an angle grinder. His accomplice finished the crime by re-forming the peaks with putty. Now a restorer can see what it’s up against.
The T-Bird was just as bad inside. Rusted-out holes in the floors were covered with layers of body filler. Note the bracing added to keep the body from collapsing while being dipped.
This neglected 1927 Ford Model T wants to be a hot rod someday, but first the solid steel needed to be separated from the rusty junk panels.
The Model T’s body is dipped into two tanks, one to remove the paint and the other to remove the rust. Sometimes a second dipping is needed for extreme corrosion, and the body may remain in the dip for days.
Things are looking better for the wannabe rod. The rust is now gone (along with a lot of the body).
The body is thoroughly washed and treated with a water-based preservative to prevent flash rusting. This gives the bodyman a few weeks to work on the body before putting it in primer. (Amazingly, this rod is actually now back on the road.)
This rusty frame for a sports car is made from heavy steel. The rust is only on the surface but it would take weeks to remove it with a drill and wire brushes, so it went to a sandblast shop for quick work.
The blaster goes to work on the roll bar. A softer blasting media was chosen that would leave very slight pitting for the primer to better adhere to.
In no time the chassis is clean and ready for a trip to the paint shop.
A base coat of epoxy primer gets the chassis ready for a top coat.
The chassis looks like new and is ready to be re-installed under a restored sports car. Wasn’t that better than grinding away with a brush?
This ’27 Model T street rod was rescued from the salvage yard and is now back on the road.
This restored Devin sports car now rides on a clean, sturdy frame.