Paint stripping with brake fluid

It will cause some plastics, not sure which ones, to become brittle and, at one time, would not work on whatever paint Kato (I believe that is the make) used. I have had good luck stripping brass and plastic with plain old household lye...mix up a batch and soak overnight. CAUTION: Do not use lye on pot or ferrous metal such as zamac etc.

| I've read many positive comments on this method, and passed them on, | too, but I've never done it myself. I'm about to try it, as it's said to | be safe for styrene. But I have a couple of questions. | | How long does it take, typically? Does it just soften the paint, or does | it lift it off the plastic? What about clean up of the stripped part - | soap and water? |
I've used the commercial product Castrol Super Clean (known as CSC in the automotive modeling world) and after a half-hour all of the paint came off the 1:24 scale plastic auto body. It softened the paint and I "scrubbed" it off with an old toothbrush.
Norm

On 5/10/2008 6:24 AM Wolf Kirchmeir spake thus:
Since neither of the first 2 replies saw answered your question (which was "how does brake fluid work?", not "what else can I use to strip paint?"), I'll try. It takes as long as it takes. More specifically, it ain't fast; be patient. It basically softens to paint to the point where it can be physically removed, so be prepared to use something to gently scrub it off (a plastic scrubber, f'rinstance). After that, yes, it'll clean up nicely with soap and water (the brake fluid is water-soluble).

It's a technique I've used quite often. I imagine the results will depend on the brand of brake fluid, the type of paint being stripped, temperature ...
In my experience the paint surface softens for about the first 10 minutes and can be washed off with gentle application of warm water and a tooth brush. At about 15 minutes the reaction starts to change and the softened paint begins to become rubbery. The depth affected seems to increase but the outer softened layer seems to gain strength. Further, (some) plastic left in brake fluid seems to change to a more powdery surface feel, which I'm not happy with. Because of those two factors, I use different stripping techniques for diecast materal and for plastics. (or is that 'but for plastics.'? ;-) - With diecasts I will place them in a bath of brake fluid for 12-24 hours, wash and return until it is clean. - With plastics I paint on brake fluid and then wash after 10-15 minutes and reapply until all the paint is removed. 3 or 4 applications has always been enough.
Greg.P.

The time is quite variable. On a hot summer day, with fresh brake fluid, some paints run off the model and puddle in the bottom of the pan in a few minutes. Other paints, colder day, fluid which had been used a few times, and the time can be hours or sometimes, never.
Temperature certainly makes a difference. I've fetched a jug from the basement and had it work very slowly. But as the fluid warmed, the action accelerated noticably.
It varies greatly. I recall a couple silver cars with black lettering where the letters fell off in one piece while the silver paint ran off in streams. Sometimes the paint dissolves and runs off, sometimes it turns into a gummy goo which must be scrubbed off, sometimes it loosens and can be peeled off in sheets, sometimes it just sits there. I've encountered great differences between manufacturers and between different colors on the same model.
Unfortunately, I had much better luck 15 or 20 years ago than I do today. I suspect changes in paint formulae and possibly changes in brake fluid composition are the cause. These days, I'm disappointed more often than not. The same can be said for every paint removal nostrum I've tried. Lye does a very nice job on some paints, doesn''t do a thing to others. Some folks swear by Pinesol, I've never had any luck with it. Ditto for Goo Gone. Ditto for Simply Green.
Or even just hot water. I think, but am not certain, that brake fluid is high molecular weight alcohols. Whatever the substance(s), it/they mix readily with water.
Bob Netzlof

Hereyago: Peteski

A couple tips.
The active ingredient in the brake fluid is volatile, so be sure to cover the jar or pan in which you are soaking your component. I find this greatly extends the useful paint removal life of the fluid.
I prefer to soak bodies in vertical jars or cans rather than horizontal trays - they seem to take less fluid to submerge the component, and the are easier to close re. the tip above. I have an old Planters peanut glass jar that is perfect for a 40' HO boxcar body.
If you find that you don't have enough brake fluid to cover the component you are soaking, remember you can raise the level by adding fillers to the jar/tray. It happens that my wife keeps her garden and flower stuff near the deep sink where I do paint removal, and she has a supply of glass marbles she once used for some display. I find borrowing some of the marbles works well to fill a soaking container, particularly if I'm working on the occasional O scale piece, and so far has gone undetected by spouse. Geezer

Ferrous metals are iron based. Zamac is not a ferrous alloy.
Don't use lye on aluminum alloys; they disappear in the lye solution.
I've used lye to degrease steel parts (ferrous alloy) with no ill effects.

"Geezer" wrote
Good suggestion, but you *are* rinsing the purloined marbles off before returning them to their container, right?
-Pete

The impurities in many zamac castings perhaps cause it to react in lye as a ferrous metal. Had some ruined car bodies some 30 years ago that really did not like lye. Perhaps I should have added "pot metal" to my note. Never tried lye on stainless.

Also remember that regular brake fluid (the DOT-3 or DOT-4 varieties at least) are hygroscopic so they absorb water and in doing so change composition. So that's another reason to use it in a sealed space (such as an old glass fish tank with a well-fitting cover).
Yep that's a good idea.
Yeah marbles are really good since they're inert as far as brake fluid is concerned and will have effect on the job at hand.
Craig.

"Peter W." wrote
I liked the part that went, "polyethylene glycol in the concentrations found in DOT brake fluids reacts violently -producing a large fireball- with some household chemicals; notably pool care products."
Sounds like a chapter form "The Anarchist Cookbook".
-Pete

... ... That is why IMO brake fluid is more trouble that it is worth for stripping models. I also had bad experiences (softened, discolored and frosted plastic) when I tried the brake fluid in the past.
There are plenty of less cumbersome methods. I use several chemicals depending on the job at hand.
If I'm stripping a metal parts I use a strong stripper such as "Aircraft Stripper". It contains chemicals such as methylene chloride and it'll strip pretty much anything. There are few others available. But if those are used on plastic parts they'll turn them into gooey mess.
On plastic I use more delicate strippers. My arsenal includes Denatured or Isopropyl Alcohol (or a mixture of one of those with a little acetone), Polly S Easy Lift Off, Scalecoat paint remover, Castrol Super Clean (or a generic equivalent) and and couple of others which I don't recall at this point.
Some of those seem to work better with certain types of paints (lacquers, enamels). I basically experiment. If one doesn't work I dunk the part in another one until I find one that will do the job.
Peteski

Wolf;
The Canadian Tire cheap brake fluid worked for me but getting yellow paint off one Atlas/Roco ATSF GP-38 took so long the plastic was affected. The expensive Canadian Tire brake fluid destroyed shells.

Ferrous metals do NOT react with lye. Mild steel, tool steel, cast iron, stainless steel - I've boiled them all in strong lye solutions to remove oil and grease. The metals were not affected at all. After removing from the lye and rinsing, the non stainless steels will rust VERY quickly because the protective oils are gone. But the lye does not affect the metal.
Zamac and pot metals are aluminum alloys. Aluminum and aluminum alloys are destroyed by lye. You can watch the bubbling and foaming as the aluminum disappears.

On 5/13/2008 6:59 AM snipped-for-privacy@mtholyoke.edu spake thus:
Actually, zamak (note spelling) is a zinc alloy (it does contain some aluminum).
More concisely stated:
Good, cheap, quick: pick any two.

Basic chemistry. In short, don't do it. As an exercize for the student, next time you're at the stupormarket or hardware store, read the ingredient on Drano.
mark

The following page may be of interest?
Cheers, N.Fotis

i like oven cleaner for stripping paint - it seems to simply not react with hydrocarbon-based plastics...