After speaking with Michael Nahm at TMT Services Corp. (manufacturers and distributors of GreaseMaster, Rusteco, and RNB), I discovered a new product on the market that they distributed as well, EFS-2500.
EFS-2500 is an environmentally friendly paint stripper, or more accurately paint lifter. Besides holding the innocuous title of "environmentally friendly" there are quite a few attributes that separate EFS-2500 from traditional paint strippers. First and most obvious upon first exposure is its low odor. While you still need adequate ventilation (and you should still wear a respirator, goggles, chemical resistant gloves, and other protective clothing when using EFS-2500), its smell is very mild compared to regular strippers. Molecular-Tech says EFS-2500's low odor comes from the fact that it contains no Methylene Chloride, Formic Acid, Carbonic Acid, or N-MP (N methyl Pyrolidone). Basically, no chlorinated chemicals or carcinogens (which means minimal to no air pollution potential) and it complies with U.S. EPA emission rules.
Second, as stated in the paragraph above, it is a paint lifter. So, what exactly is a paint lifter and how does it work? Molecular-Tech says it works by osmosis, working its way through the pinholes in paints and primers, breaking the bond between the substrate and coating. When it breaks the bond, the paint lifts off the substrate as a film (including primer and top coat). It doesn't melt the paint (and there is no leeching) so once it is lifted, it can be removed by rubber squeegee or pressure washer in single sheets.
Third, it passed the requirements for disposal into waste water systems under the BC Waste Management Act (Canada) and causes no hydrogen embrittlement (passing Boeing specifications).
Fourth, it's non-acidic, nontoxic and nonflammable as well as biodegradable.
While all that information is interesting (if not amazing), how useful is it? Molecular-Tech says it can be used in a number of applications. It can be brushed-on, rolled-on, used in airless spray systems, immersion tanks, or it can be used as a dip and then hung to allow the gel-like substance to work. They claim it does a great job clinging to vertical and overhead surfaces (and from what I've seen in use, I'd have to agree). They claim it takes 1-6 hours in most circumstances to work (77° F temperatures) but that it can work for an extended period of time (up to three or four days in low temperature applications around 41° F). They also say it evaporates slowly once it has lifted the paint and keeps it moist and pliable for well over 24 hours. They also claim paint lifting time can be accelerated by elevating surface temperature to 85° F.
Molecular-Tech also says it's effective on a number of different surfaces and with a number of different coatings (including clear coat and moss on wood). Although I haven't tested many of the applications and surfaces, it is supposedly effective for all metals (including aluminum, carbon steel, stainless steel, cadmium plate, magnesium, and titanium), wood, fiberglass, paint film, gel coat, concrete, brick, ceramic, plaster, stone (although you may have to apply it extra thick on porous materials like brick, you should also watch its progress carefully on fiberglass and other composites). They also claim it's effective for removing graffiti and prevents the localized breakdown of passivating oxide film.
All those claims make for a pretty tall order to fill, and I've done my best to test it on what I can. Take a look below to see the results.
Part 1: Adhesive Removal
I decided to start with the adhesive removal test, because it was the easiest to execute. The tools I used for this test were an old tooth brush (for application and secondary removal), a small body filler spreader (for primary removal), a bottle or rifle brush (for secondary removal), a wet rag (for rinsing residue and neutralization), a dry rag (for drying), Mechanix Wear solvent gloves (for hand protection), and a respirator (for respiratory protection).
Timing Chain Cover
I applied the EFS-2500 to some gasket adhesive on an old, cracked timing chain cover that I now use for engine masking. The application thickness recommended by Molecular-Tech is twice the thickness of the material you are removing, so I daubed the EFS-2500 on with the toothbrush. Click image to enlarge.
Before Adhesive Removal
Although Molecular-Tech recommends leaving it for 1-6 hours, I left it over night because I got to it late and I didn't want to wait an hour or more to remove it. I finally got back to it 12 hours later and (as you can see in the photo) the sealant appears lifted and the stripper is in the process of drying. Click image to enlarge.
After Adhesive Removal
After 12 hours the gasket adhesive came off easily with the body filler spreader, and even easily removed the spare gasket material the adhesive was holding to the cover. The only thing I wasn't able to remove with the spreader was the adhesive that was down in the bolt holes. For those, I used the bottle brush. Click image to enlarge.
Another Adhesive Test
After my first successful test of EFS-2500, I decided to try a test with some slightly different parameters. The over-the-counter gasket removal chemicals I've found state a 15-20 minute working time to remove gasket material, and I wanted to find out how EFS-2500 compared. Click image to enlarge.
Another Adhesive Removal
After 10 minutes the EFS-2500 was still as wet as when I applied it, and I couldn't tell if it had lifted the adhesive. I started scraping with the plastic body spreader anyway. Low and behold, the adhesive came right off except for one very tiny spot that I scrubbed free with the toothbrush I used to apply the stripper. Again, I used the bottle brush to remove the adhesive from the bolt holes. How did it compare to the chemical gasket removers that I've used in the past? Considerably better. It usually requires several messy and smelly applications of the gasket remover (by spray can) before the gasket and adhesive finally cleans off completely. Click image to enlarge.
Part 2: Powder Coating Removal
Next up is powder coating, which I was sure was going to be the single most difficult challenge for EFS-2500.
The tools I used for this test were a bristled paint brush (for application), a medium-sized body filler spreader (for removal), a bucket of soapy water (for cleaning and neutralizing), a bucket of clean water (for rinsing), a paper towel (for drying), Mechanix Wear solvent gloves (for hand protection), and a respirator (for respiratory protection).
This is a pulley I got off of my old '89 Mustang. It's a no-name part that was put on with two other unmatched pulleys. Since it was powder coated and I had no use for it, I decided it would make the ideal test candidate (especially since I could see how well the stripper worked on a vertical surface). Click image to enlarge.
Application on Powder Coating
Here the EFS-2500 is freshly applied and it clung to the vertical surfaces of the pulley with what I thought was pretty amazing tenacity, even with a thick coating applied. Click image to enlarge.
Before Powder Coating Removal
After only an hour, the powder coating had already lifted pretty well. I wasn't going to have time to get to it until the next evening, so I left it to pickle in its own juices over night. Click image to enlarge.
After Powder Coating Removal
Not only was it extremely effective (in fact, it was flawlessly effective) it was easy to remove with a body filler spreader. It was equally as easy to neutralize. I just dunked it in a bucket of soapy water and washed it clean, then rinsed it with fresh water before drying it with a towel. Click image to enlarge.
Part 3: Paint Removal
Last but certainly not least we come to paint removal. This exercise was an interesting learning experience. This test added only two other items to the list of tools used for the powder coating test (plastic bags for collecting stripped off paint, paper towels, and a terry cloth towel for drying the panel stripped in this test after it was cleaned up). The only other change was the use of more paper towels.
'66 Mustang Rear Valance
For this test, I pulled out a panel I had purchased for a past project that I had no plan on using for anything else. I expected this test to be nowhere near as hard as the powder coating test (since my experience stripping powder coating with chemical strippers has been...trying to say the least). Boy was I wrong. I've read that the use of chemical strippers isn't as easy as it sounds, and that often a sander is employed to remove stuck on residue. After stripping this panel, I can see why. I will say this much though, this stripper did strip the panel completely using only a body filler spreader. I'd just like to take a moment to send a special thanks to Patty for all her help with this article. Click image to enlarge.
Application One on Paint
This was the first time I applied EFS-2500 to paint and learned shortly thereafter that to get the most expedient results, the correct amount to apply would best be described as "thick." I didn't apply it thick enough this first time and my experience with it has lead me to conclude that had I applied it thick enough this first time I could have saved myself an extra application and removal step. Click image to enlarge.
Before First Paint Removal
Six hours after I applied my first coat of EFS-2500 I was rewarded with wrinkly paint. The paint had actually started to take on this appearance about an hour after I applied the stripper, but I wanted to be sure to give it enough time to work through as many layers as possible. I did, however, decide to see how well it worked after a six hour interval rather than wait more than 24 hours (which was the next time I could get back to this project) and risk it drying out. Click image to enlarge.
After First Paint Removal
This was when I discovered this panel had...experience. Not only did it have dings, it also had two coats of paint. One coat of what looked like a high build primer and one coat of what looked like a base coat primer of some kind. This is when I knew I had my work cut out for me. I was hoping that EFS-2500 would miraculously work its way completely through every layer of coating and lift it all off, requiring a minimal amount of effort on my part to wipe it off with a spreader. So reality didn't exactly agree with my fantasy, but what was lifted came off with a minimal amount of effort by simply squeegeeing it off with the spreader – after which I washed it off and applied a second "thick" coating of the stripper. Click image to enlarge.
Before Second Paint Removal
Okay, I didn't follow the established format above by starting over again with a photo of the second application of EFS-2500 that would illustrate what I've found to be the most effective application volume, but I have a good reason for that: I don't have a picture of that step. Instead we jump ahead to the paint and primer lifted by the second application. From what I've seen of the product applied correctly, it is far more impressive than what this photo shows. However, to be fair, the stripper had to work with that high build primer that fought to stay on like nobody's business. I think, due to my understanding of how EFS-2500 works, the "red" primer you see may actually be a primer sealer as well (but I have no proof to back up that supposition). Click image to enlarge.
After Second Paint Removal
This was the same condition of the part after a proper first application of EFS-2500. In this case, of course, it was after a second application. This time I left the stripper on for 24 hours before removing it. Again, I just squeegeed off the paint and primer that was lifted by the product. As you can see, the red primer fought a lot harder than the paint, even the exposed primer. Click image to enlarge.
Application Three on Paint
Here is an illustration of what I found to be the most effective application of EFS-2500 to use. You might find a thicker application to be more effective, but with a brush I found it difficult to get it any thicker and even at this thickness I was daubing it on extra thick and then spreading it around like icing on a cake. Click image to enlarge.
After Third Paint Removal
I think it's obvious now that I wasn't able to get all the photos for this format, but the "before" condition of the primer was similar to the previous "before" photos. My then-girlfriend Patty did 90% of the work in this photo, which was more aggressive than in previous paint removal steps. I was running out of time to get this test done and we decided to start scraping at the un-lifted primer with the body filler spreaders. For the most part, the un-lifted primer did come free, especially if it was left to allow the stripper to work, even if only for a few minutes. Click image to enlarge.
After Final Paint Removal
After another 24 hour working time, I was able to remove the final layer of primer by scraping with the body filler spreader. The panel came completely clean and it left the galvanized coating underneath untouched. Oddly enough, while the red primer was tough to remove, the base primer was even more difficult. I'm not sure if it was a standard, self-etching, catalyzed or anticorrosion (zinc based) primer but it was trying to stay on for good. Click image to enlarge.
Another Paint Test
After discovering that my first application on this thick paint wasn't thick enough I applied it a second time over untouched paint to see how quickly and effectively it would work. The result of one application and removal step were as effective as the first thin coating and second thick coating as illustrated above. I've included all three steps above (application, before, and after removal photos) to show what kinds of results EFS-2500 can produce with a thicker application.
As you can see in the middle photo, the paint lifting is far more impressive.
Since I was able to get all the way to the substrate in quite a few areas with this application, it leads me to think that it's possible that a proper application of EFS-2500 would be able to lift all the paint in one application. Click image to enlarge.
Stir to uniform consistency
Apply a very thick wet film to 30-40 mil
Store unused material in tightly closed containers
Clean application equipment with water
Airless paint sprayer
Apply at twice the thickness of the coating to be removed
Scrape the paint film off with plastic scraper or pressure wash then rinse and neutralizes with soapy water. Separate the solid paint and residue from the liquid. Then contain the solid in a drum for disposal.
To be used by professionally trained personnel using proper safety equipment
Use only with adequate ventilation
Please refer to Material Safety Data Sheets (MSDS) provided by the manufacturer
First and foremost, the odor is much less atrocious than regular paint stripper, although I still wore protective gear to keep me safe and healthy as per the EFS-2500 MSDS recommendations.
Second, the lifted material comes off with ease and if you need to speed removal time un-lifted material can be scrubbed (although all un-lifted material probably won't always come off).
Third, it's easy to neutralize and wash off with soap and water.
Fourth, disposal is simple and safe.
All in all, I was impressed with the effectiveness and user-friendly nature of EFS-2500. It was completely effective in every test I conducted (although repeated applications were necessary on some coatings). The way it lifted coatings made them simple to remove. Basically, it was superior to traditional strippers I've used in every way.
Time and technology march on and it's nice to see that so do the safer and healthier alternatives to traditional methods.