Article - Paint stripping using brake fluid Written by: Stevo309

The article explains how to use brake fluid to strip paint from hard (ABS) shells. Please be warned that this technique does not apply to polycarbonate (lexan) shells!

Sometimes if you want to re-paint a model it's acceptable to simply wet sand the existing paint and apply a new top coat, but in many cases this is not the best way as the thickness of paint can make the shell lose detail. The existing paint may also not be good enough even as a foundation or might react with your lovely new paint. For these reasons it's generally best when you can to strip shells of all their paint giving you an effectively new shell to work with. This article explains how to do this using car brake fluid.

The equipment
For this job I recommend the following equipment:

  • Large crate/tub with lid
  • Dot 4 brake fluid (8 litres or more)
  • Toothbrush
  • Wooden toothpick or wooden scewer
  • 1000 grit wet and dry paper
  • Rubber gloves

For most shells you will need around 8 litres of fluid to allow a shell to be completely submerged. A suitable plastic container is also required. Stacking storage crates are pretty good for this, a lid is a good idea to avoid splashes or anything dropping into the fluid. If you can find a slightly larger crate this can work as a good lid.

The brake fluid itself needs to be as cheap and nasty as possible. Modern higher grade semi-synthetic brake fluids of higher than Dot 4 are not as good as they contain chemical corrosion inhibiters to prevent damage to the brake components on the car. We are actually looking for the corrosive properties so go for the cheap Dot 4 fluid it'll work fine.

Please remember to always wear rubber gloves when you're handling this stuff, it's pretty nasty and should be washed immediately from your skin if it comes into contact with it. Seriously, do it in the garage or shed and nobody needs to see you wearing those pink or yellow Marigolds!

To get started simply strip your shell of all it's ancillary components and decals and submerge in the fluid. We're starting here with a Blazer shell that needs some TLC. The first time you do this is quite scary, especially if it's a valuable and vintage shell, but don't worry the brake fluid is not corrosive enough to damage plastic. If it was it would have come through the container it came in or the crate you are using remember?

Bear in mind that the rate of reaction here is dependent on the temperature, if your crate is in a cold shed or garage it will take longer for the magic to happen. The warmer the place you can do this the better. It may take some time though so find somewhere that is out of the way.

The wait…
All you have to do now is wait and keep an eye on things. I've had paint come off in under 24 hours but that's unusual. Expect to wait a few days before you see the paint starting to blister up. Once this is happening it's worth working the brake fluid into the paint with a toothbrush. This will remove loose blistered paint and work the fluid into the remaining paint. If the paint is in multiple layers you may need to repeat this process a number of times until you are seeing bare plastic. If the shell is not completely submerged it's best to "baste" the shell with fluid using a pouring jug as often as possible. Of course you can always turn it over in the fluid from time to time.

If you check progress after a few days and nothing appears to be happening leave it a while as I have had some take up to a month before a reaction is taking place. It just depends on the brake fluid and the paint that's been used, some react more than others. Some of course don't react at all which is where more drastic action can be taken (watch out for future articles). This method is a model safe way of doing things and in my experience has worked with probably 80% of shells I have tried it on.

Of course you can use this technique on other things that have been painted such as wheels, drivers and other body parts. I haven't tried it on anything chrome that's been painted so i can't be sure it wouldn't affect the chrome plating.

What next?
Well it's just a job of removing all the paint. On smooth a simple shells such as a Sand Rover you can expect most of the paint to come off in the brake fluid but it most cases the paint will cling in the details lines and corners of the shell. To remove these I use a toothbrush and/or a wooden scewer. This can take some time but it's worth doing it properly, if you leave paint in the details of the shell it will show when you paint it and I'm sure you don't want to have to strip it again?

The cleanup
Finally it's time to clean the shell ready for paint. To do this scrub the shell in hot water with washing detergent in it, at this stage you might wish to key the shell with fine wet and dry paper giving it a rough finish for paint to stick to, and remove any last traces of paint on the shell again using a wooden screw or toothpick. You may find that the shell is stained from the paint used, this is quite normal and there is not much that can be done, you can wet sand some of it out but this isn't necessary as you'll be re-painting anyway.

Finally just rinse the shell in clean water and leave to dry ready for new paint!

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