One of the big, time consuming jobs on any project vehicle (unless you are building one from scratch with raw sheet metal,) is stripping off years of old paint, primer, and anything else on the body panels. There are as many different ways to strip paint as there are types of paint to apply. Many times, especially with older projects, there may be multiple layers of primer, urethane, lacquer and enamels between the bare metal and the outside world.
Matt took an extra hood from a Chevrolet Monte Carlo that was a perfect example of this and used it to show the various mechanical, chemical and abrasive methods that Eastwood offers to take off old paints and primers. Here on the table you can see various sanding, grinding and other a mechanical methods to get the paint off the surface. Right by Matt’s elbow you can see several sizes of the Eastwood Gel Chemical Paint and Powder Remover. And on the right of the screen you can see the big blue tank of the Eastwood Abrasive Media Blaster, for spraying various grits of media at the panel that will eat the paint off.
Of course you always want to wear proper safety gear no matter what you are doing. Besides the normal dangers when you are grinding and sanding, working on old cars can expose you to lead paint and body solder, as well as rust and tetanus. You should at least have a pair of safety goggles on, and a filter over your nose and mouth to keep the dust out. A pair of sturdy leather gloves gives you something else to cut or burn before you get to your actual skin. When the particles really start flying, a clear fold down full face shield is a good idea as well.
Hand Sanding with a Block
This is the cheapest and easiest method, but that is only if you don’t value your time, or you are just looking for an upper body workout. Mister Miyagi had great luck with tricking local teenagers into doing this by promising to teach them karate.
The advantages of the paper and sanding block method are that there is very little to buy before you get started, it is gentle to the metal, and you can get into really tight, irregularly shaped areas. The main disadvantage is that it will take what seems like a year to sand off the old paint on the whole car. After 30 seconds of work, Matt barely was able to get through the top layer of black paint and down to the white.
Dual Action Sanding Disc
Next up is the same 80 grit sand paper, but this time spun by a dual action sander, sometimes called a DA or random orbital. This works very much the same as the hand sanding, only the air or electricity provides a lot of the work, instead of your arm, shoulder and back muscles.
As you can see, in the same 30 seconds the DA Sander was able to take off all the black paint, and in the one spot Matt focused on, three other layers to expose the base metal. The downsides of the DA method are you will burn through a lot of sand paper, you need a good air source, or an electric DA to keep up and do the whole car, and it’s really only suited for larger flat panels. The advantages over doing it by hand are obvious, but it’s not the best way to remove paint from a whole car.
4 1/2 in Flap Discs
The next item often used to remove old paint is the flap disc that attaches to your common angle grinder. It’s basically a flat disc with little pieces of sand paper glued to it in an overlapping pattern. All the edges of the paper give it a much more aggressive bite than just a flat disc like the one on the DA.
The problem is it’s usually too aggressive. Sure this tool will make short work of all the old paint, but if you aren’t careful it will leave a ton of gouges in the metal. Use too much pressure and it will even grind grooves in it. All this means more work after stripping with filler or high build primer to undo the damage you just caused taking off the paint. The flap disc is especially dangerous around edges and body lines as they can grind right through the metal. They do work great though for grinding and smoothing welds and surface rust.
Hook & Loop Cleaning Disc
Next up is the Eastwood Cleaning Disc, which is like a super heavy duty version of the green scrubby you use to clean pots and pans when washing the dishes. It’s available in a similar form to the flap disc, glued to a fiberglass backing for use with an angle grinder, but for big jobs it’s much easier to use the Eastwood hook and loop version. The hook and loop kit has a dedicated disc that screws onto your angle grinder, and cleaning discs that stick to it with a heavy duty version of Velcro. The discs are available in 80 grit and a 320 grit and are easy to change.
The woven material of these discs is great because it doesn’t come apart when you are using it and fling pieces everywhere. The flexible nature of the disc and backing pad make them much less dangerous to edges and body line too, and they don’t gouge if you push too hard. As you can see they make short work of blasting through all this old paint too. But if you use the disc in one place for too long it is possible to get the panel too hot and warp it, so keep moving.
Hook & Loop Stripping Disc
Next up is the less aggressive 320 grit hook and loop disc. This one does the same job it just takes more time. It’s less aggressive and more suited to taking off the clear coat and prepping a recent car with just 1 coat of paint on it.
As you can see it leaves a smoother finish, but it takes longer to cut though the paint. Eastwood sells a kit with both discs and the hook and loop attachment for your angle grinder. It’s great to start out with the more aggressive 80 disc, cut through the old layers of paint, then smooth it all out with the 320 disc.
Here’s a before and after on the same patch of hood we used the cleaning disc on originally, showing how you can use the stripping disc to finish the job and get down to smooth bare metal. Here is before.
And this is after.
3M Plastic Bristle Disc
Next is the plastic bristle disc from 3M. These bristles are very tough and come attached to a disc that screws onto a common 4 1/2 inch angle grinder. It works exactly the same as a wire wheel would, only the discs don’t fall apart as easily as wire wheels do and they are gentler on the metal.
As you can see, it’s a little more aggressive than the red stripping pad, but not as much as the hook and loop cleaning pad. And look at how smooth it leaves the metal after the paint is all gone! These bristle discs are very durable too and last a long time, so they are great for big jobs like a whole car. Be careful around edges though, because the bristles can catch an edge and get broken off, and they will hurt if they hit bare skin, so wear long sleeves and a face shield.
Roloc Quick Change Surface Conditioning Discs
These little discs are very similar to the hook and look stripping discs, only they mount differently and they are more flexible for sanding irregular surfaces. On the back on these discs is a little threaded stud that screws into a flexible rubber mandrel you can attach to any drill.
The softer, flexible nature of the mandrel allows you to use these for areas that aren’t flat. Also because these are so small, they are great for getting in tight areas like window frames and such. They are available in 2 and 3 inch sizes, and are commonly referred to as “cookies.”
That’s it for the mechanical methods of stripping old paint, but there are other ways to take off paint that don’t involve spinning discs.
Eastwood Paint & Powder Stripper
Guys often wonder about stripping paint off with chemicals. How well does it work? Is it safe for the panel? It is safe, and it works great, especially in areas that have tight curves or something that would prevent you from getting a cleaning disc or bristle disc in there.
You do need to wear rubber gloves though, because if you get this stuff on your bare skin it will burn.
Then it’s just a matter of brushing it on, use these acid brushes that are made of a plastic that won’t melt in the chemicals.
Wait 30 minutes or so and start scraping it off (Matt cheated and applied the stripper before the cameras started rolling so it would be ready now.)
As you can see the first application took off almost all the layers of paint. You could use mechanical means to strip the rest down to the metal, or apply the stripper again and you should have a totally clean bare metal surface. To make it even more effective, especially if dealing with modern clearcoat, use the DA sander to scratch through the surface first, then apply the stripper.
Finally, the last best method, and the most expensive to get set up to do, is media blasting. Media blasting sprays various small particles like ground glass, aluminum oxide, silicon carbide, and walnut shells, at the panel with high pressure air. For softer surfaces like fiberglass and urethane, soda blasting does the same thing with a softer media similar to baking soda. You do have to be careful though because media blasting can still warp a panel if you stay in one spot for too long and it gets hot. You also need to tailor the media to what you are stripping. Use too coarse of a media on a soft metal like aluminum or pot metal and you will be left with a rough surface that will take a ton of work to correct.
Eastwood offers big, pressurized media blast tanks that are great for doing entire cars, or blasting a frame and chassis if you are doing a frame off restoration.
If you don’t want to spend the money and make the commitment to a big set up like this, Eastwood also offers a Small Blast Kit that is very affordable, and great for doing just the problem areas of the body panels.
The best places to use the Small Blast Kit, or any media blasting really, are problem areas like these intricately shaped edges of the hood. There is no way you are getting a cleaning disc or wheel in there, which means you could be there for hours with a piece of sandpaper stripping the paint by hand. The media blaster will make short work of this.
Eastwood Fast Etch
Once you are down to bare metal, you need to make sure you protect it so it doesn’t rust immediately. Eastwood Fast Etch not only helps eat away minor surface rust and prep the bare metal for paint, it also leaves a protective phosphoric coating. The coating will protect it for a good long time, and can easily be wiped off with PRE painting prep with just a rag before painting.
If you do have surface rust on bare metal, you can spray the fast etch, let it work for a few minutes, then just wipe it off. Here is before.
And this is after. Obviously it could have used a few more minutes.
To use Fast Etch as a protective coating, just spray it on and leave it on. It will eat into the metal, then react to create that phosphoric protective coating.
So those are basically the most popular methods of removing paint and getting down to bare metal. Of course if you don’t want to do it all yourself you can always send the whole body out to be media blasted by a professional. There are also places with tanks of stripper so large a whole car can be submerged to eat away the paint and rust, but there is no way you are going to do something like that at home.Click Here To Read Full Post...