91% Isopropyl alcohol as paint stripper

I've never had it harm plastic.  I've left Intermountain boxcar shells submerged in 91% for up to 3 weeks; zero plastic problems.  There are some paints 91% won't strip, mostly older lacquer stuff, but most modern (post 1995ish...?) acrylic paints will dissolve or lift off in sheets.  Not all pad print inks will strip, but most do.  Best news is if it fails to strip, there is no damage!  FWIW, 91% often leaves a light "blush" or haze on dark colored plastics.  Its probably there on light colored plastic too but you cant see it. I've never had a problem with this haze during later painting.   

When I was just experimenting (I am not even remotely experienced) with some paint/lettering removal a few years back, I noted even the 70% Iso I had ate into some plastic.  And it was nothing like a 24 hour submerge, I think I was applying it with a q-tip and some mild rubbing.  It didn't totally deform the plastic, but I think I noted the molded in wood grain detail was being eaten away, so it was becoming noticeably more smooth in the area I was trying to remove the lettering.

I'm pretty sure it was an MTH bobber caboose, so I don't have a specific "apples to apples" Atlas story for you.

Good luck with your project.

{edit: reading the more experienced member's descriptions above, maybe my problem was the rubbing?  I defer to their expertise on risk of any danger to the plastic}

-Dave

Think I'll stick to using Isopropyl to clean track as well as engine wheels and rubber tires to ensure good electrical conductivity.

I used to use brake fluid until I tried stripping 90's era Williams paint.  Nothing touched it and I tried alcohol and it worked great with a lot less mess.  Been using it since, it just normally works faster than this car - Atlas orange New Haven 50 ft double door boxcar.

I have a pair of Weaver E units that really nothing worked. I tried ScaleCoat stuff as I assumed it was painted with Scalecoat. I tried 91% alcohol then I tried brake fluid. It took all three and a lot of elbow grease with a tooth brush.

Dick

I just had this conversation with one of the guys at Atlas.  It boils down to the plasticizer used in the plastic resin.  Sometimes isopropanol 91 will soften certain plastics.  I guess this is where I use the expression...your mileage may vary.

Lou N

I have used it on some N scale cabooses a few years back. I let the parts soak for a day then scrubbed with a toothbrush, resoaked for another day and scrubbed again. Finished up with scouring powder/dish soap scrub with toothbrush to get the plastic prepped for new paint. Worked well and the plastic was okay.

I've used 91% alcohol and brake cleaner, prefer the alcohol. I have 4 bottles of 91% right now, got it from CVS pharmacy.

Get a length of PVC pipe that your piece will fit into and glue a cap/plug to the bottom of the pipe.  If long enough you can submerge the whole shell into the pipe.

Don't be in a hurry because the 91% is not.  An old toothbrush is good for scrubbing just watch any attached parts to make sure they don't fall off.

You'll be surprised at how much detail is on some of these mass-produced pieces.  All factory paint seems to be a bit thick IMO.

At the suggestion of a friend, I just used 91% for the first time on a vintage (1980s) Altas/Kato HO scale RS-11 painted in N&W Peslar(?) Blue. After a couple hours, not a lot happening when scrubbed with a toothbrush. I left it to soak overnight and the next day the paint came off with some scrubbing without damage to the old plastic.

My friend uses it to harmlessly strip Proto 2000 HO products and it doesn't bother the clear plastic used for windows. He's sold on it, and I'm beginning to be.

Obviously from reading the above: YMMV!

Andre

You can also try soaking in generic Lectric Shave, then rubbing with a chunk of Magic Eraser.  While this won't attack the plastic, it will discolor it if not rinsed off completely.    

Mitch 

I have stripped 2 Atlas O Alco C-630’s using 91%. The paint came right off. After a couple hours. I use a tooth brush to scrub the old paint off. It doesn’t not hurt the plastic or soften it. This is my go to method for stripping paint off models. 

I recommend if your loco has a painted metal frame. Id make sure to remove all plastic and use acetone on it. Or get it media blasted, or just paint over the existing paint. The paint they use on the frames are a lot more durable. 91% barely touches it. I did two of these and I did acetone on one and spent way to much time scraping the paint off. The 2nd one I painted I paid a local powder coating shop to blast the frame. Worth my money. 

Two day soak, checking every 24 hrs, no detrimental effect on the plastic.  99.99 % paint off with a little toothbrush work.  Currently in control purple stuff as a final strip.  Good final bath and ready for paint.