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MG MGA - Cleaning Up Silicone Fluid

What's the best clean-up liquid for silicone brake fluid?

thanks, Tyler
tyler

Hi Tyler. I found that lacquer thinner did a pretty good job, although it can eat through paint if excessive quantities are used. I found that just dampening a rag with thinner, and quickly working the area of the spill removed the brake fluid quite well. Cheers! Glenn
Glenn

Cyclohexane, if you can find it. Toluene from a paint or hardware store will also work and is a bit less aggressive on paint than lacquer thinner. Non-polar solvents are best...

Steve
Steve Brandt

Depends what you're trying to clean. If your brakes or clutch systems have leaked or you spilled the fluid somehow, just wipe it down with a rag. It will shine your suspension like new! Common show trick. Griots Garage even sells it as "Undercarrage Spray"...pure silicone.
Paul Hanley

Tyler

I wonder if you have done what I did a few years ago? I was using a bleeding kit, attached to the master cylinder and pressurised by air from the front tyre. Having completed the bleeding process I disconnected the kit from the master cylinder before first disconnecting the connector from the tyre. The result was about 30psi of air blowing directly onto the MC and scattering silicone fluid all over the engine bay.

Seemed to wipe up ok. One bonus is that the external surface of the MC has never rusted, unlike those that are filled with traditional fluid!

Steve
Steve Gyles

Steve - If you ever have the car repainted, be sure to tell the painter about this incident, it will make a world of difference in how he handles the job, and result in a much better final result if he knows he is dealing with old paint that had a bath in silicon. Cheers - Dave
David DuBois

Dave

Well I know! I have previously had experience of this sort of thing to my cost. Even old silicone-based car polishes can cause problems.

The next respray of the old girl will be back down to the bare metal again. I do all the painting myself. The last time I painted her I signed up for evening classes at the local college so that I could have full use of their professional spray equipment and ovens.

Steve
Steve Gyles

You might try Simple Green if all you need to do is remove a film of silicone off of the surface. I am not sure why it seems to have worked so well for me, maybe it is the non-polar aspect of its chemistry? I do know that it is supposedly a cleaner that "rinses free", leaving virtually nothing behind. Perhaps Steve Brandt might be able to expand on his understanding of chemistry for us ~ speaking for myself, I know it couldn't hurt to know better what and why.
Bob Muenchausen

Gents,
Dupont Prep-Sol solvent is used to wipe down surfaces prior to coating. Removes waxes, silicone, grease, etc.

Safety Fast

Jim Haskins
J. M. Haskins

Bob M:

Simple Green is a water-based formulation that is designed to remove grease by surfactant action. That means that the active ingredient(s) molecules have both polar and non-polar functional end groups to sequester the grease with the hydrophobic end and render the resulting micells (molecules of grease surrounded by surfactant molecules) soluble with the hydrophilic end groups. That is a general description of how household and commercial water-based formulations work. (This approach is becoming increasing popular due to environmental and health concerns.) I would have to obtain a bottle of Simple Green to be more specific.

The mechanism of dissolving grease using surfactant technology is quite different than that of using solvents. With solvents, the rule is "like dissolves like," so for greases, which are non-polar and hydrophobic, use a similar solvent. For fingernail polishes and lacquer paints, use solvents with polar groups, like acetone.

It is also possible to use bases to remove hydrocarbon greases and fats (Ammonia and oven cleaners are a couple of examples.) These work by reacting with double bonds (sites of unsaturation) in hydrocarbon greases to form water-soluble compounds. It's called saponification (or soap making).

The use of cyclohexane and toluene as solvents to remove silicone greases and oils is something we've done in the lab for decades. Some of the other solvents we've used work better, but are relatively hazardous and not generally available to the public and are more toxic and paint-aggressive. Part of my work involves the use of ultra high vacuum (UHV) equipment and surface analysis of a variety of materials. When silicone contaminates such a system, it is a MAJOR problem, since it has such a low surface energy that it "creeps" over everything. The other postings about paint preparation to remove silicone oils and greases are dead on. Nothing sticks to the stuff and if it is painted over, the paint will eventually flake off. The up side is, there will be no rust underneath.

Hope this is what you were after. If not, email me since this chemistry lesson really is a stretch for the MGA BBS.

Steve
Steve Brandt

Steve,
I thank you. I had just two semesters of College Chemistry 35 yrs ago. Not much beyond the basics is still with me at this point, but I do like to compare what appears to make sense with what is KNOWN to make sense. ;-) I just always like to know the chemistry/physics/etc behind what I have read or been told is true, or at least as much as I can understand.

I appreciate having some solid info and a better understanding of just what the phrase, "rinses free" actually means and how it works. I have only just known that this was the active cleaning principle of the product (from reading), and that it seemed to do a decent job of flushing contaminants off of surfaces for me (empirical experience).
Bob Muenchausen

Dow Corning, OS-2 is an Ozone Safe, no VOC fluid made to clean up silicone products like brake fluid and both cured, and uncured RTV silicone rubber.
OS-2 is a very thin silicone fluid which is often used as a reducer for RTVs to make them paintable or sprayable.
You can get it from bearing houses like Motion Industries, Applied Industrial Technologies, Kaman Industrial Technologies and many regional distributors.
S.R. Barrow

This thread was discussed between 09/01/2005 and 18/01/2005

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