keeping oxidation from coming back - PeachParts Mercedes-Benz Forum

otto huber · #1 04-26-2010, 07:02 PM

I just finished removing a lot of oxidation from the top of my '78 240D with rubbing compound. How can I protect the paint from further oxidation in the future? Thanks

JohnM. · #2 04-26-2010, 07:54 PM

Once paint has oxidized, it will forever want to re-oxidize. Applying some cleaner wax and then a top coat of something shiny will help after rubbing compound. Also, keeping the car out of direct sunlight helps the most. At this point you are maintaining whats left of the paint, and taking care of oxidation as it reappears.

Strife · #3 04-27-2010, 12:05 AM

I swear, that claying a car, and doing a serious polishing afterwards with rubbing compound, will re-melt and flow the surface of the paint on a microscopic scale and leave less surface area to re-oxidize.

TheDon · #4 04-27-2010, 12:12 AM

a proper polishing with a polishing DA can really help.. followed by a wax and then sealer.

If you want to warm the paint while doing it use a rotary but you need to know what you are doing

JohnM. · #5 04-27-2010, 12:12 AM

Quote:

Originally Posted by Strife

I swear, that claying a car, and doing a serious polishing afterwards with rubbing compound, will re-melt and flow the surface of the paint on a microscopic scale and leave less surface area to re-oxidize.

If we are talking a real polisher here (rotary), then yes, I agree.

cjbrown · #6 06-18-2010, 05:23 PM

A synthetic polymer wax or sealant will hold up best to weather. Reapply every 2-3 months.
3M has good product as does Mothers and McGuires.
An old favorite of mine woth trying is TR3 Resin Glaze. I use it for all types of hand work, cars boats and bikes.

For auto pain restoring there's nothing like a wool wheel with polishing compound, followed by a sealer/glaze/swirl remover and a fine wool wheel, and then a topcoat of wax or sealant. The modern iteration of this is the foam polishing wheels. I have never taken the step up to these techniques, but the pros and body shops use them exclusively. I still use carnuba was as a topcoat on the cars, but it washes off and dries out within a few weeks.

You might review Griott's Garage, and topoftheline.com for a good source of detailing supplies. The latter has a product called TERMINATOR, a polymer paint sealant - very happy with results on the fiberglass sides of my motorhome.

My favorite detailing and polishing products has always been 3M, but the competitors products seem to be just as good. In the marine world they swear by COLONITE waxes and polishes.

jmk · #7 06-19-2010, 02:46 PM

JohnM. is correct. Coatings will forever oxidize.

There is only one way of reducing visible oxidation: use a base/clear system. Now the clearcoat will oxidize. We live in an oxidizing atmosphere, and no amount of wax, sealant, etc. will stop it. (Every one I or other associates tested actually accelerated the oxidation process, not retarded it.) You will have oxidation of the clear coat, but it takes many years for that to be visible. Also there are UV absorbers and hindered amine light stabilizers that are added to clearcoats to protect the coatings and pigments from UV damage.

Clearcoat is the only relatively pernament sealer of a car's color layer.

Remelt and reflow the coating with a DA orbiter? Not likely. What is probably happening is you are removing more of the oxidized surface and have more previously unexposed paint visible. More unweathered paint is visible; it is then a longer period of time before oxidation is noticeable. Rubbing and polishing compounds work by removing the damaged surface layer, not by melting in a coating. Rubbing compounds and the numerous waxes, polishes and other materials used in detailing are not designed to dissolve the coating. I have seen when that has happened when a wax unintentionally melted the coating--you would not like the result. Toyota did not also, and they were hoppin' mad about that problem.

With an old fashioned lacquer, you may be able to melt in and reflow since the polymer does not chemically change upon curing. Since I rarely worked with lacquers, I do not really know even if those could be remelted.

I actually doubt it with the type of materials in used in automotive lacquer, but it may be possible. The material is very different from shellac used in French polishing. Shellac has much lower molecular weight, which makes it easier to redisolve. French polishing also uses alcohol, which is an excellent solvent for shellac. That is the only painting technique that I know of that uses a remelt application method.

Even wet sanding of phenolic varnishes of brightwork on wooden boats has no amount of reconstitution of the top surface layer: you are just sanding it smooth and reapplying until the top layer is nearly perfect in smoothness.

Modern OEM coatings (since the 1960's) are reactive and would be too large and interconnected for a remelt of the surface. As I said earlier, you do not want that to happen.

cjbrown · #8 06-19-2010, 03:19 PM

All well and good JMK. However I doubt an overall clearcoat over old paint is the solution the OP was looking for.

jmk · #9 06-19-2010, 05:35 PM

Probably not, though it is the only effective solution that I know of other than keeping your car out of the elements and keeping it clean. And clearcoating the monocoat is not a good solution, don't misread what I am trying to say.

I do think that most of the durability benefits people are perciving from waxing are from simply washing the car with a mild soap solution, rinsing, and drying the car before spotting can occur.

I'm just trying to inform people the reality of how paint is made, how it works, and how to best keep your paint protected for a long time. Some issues like this one aren't as critical as the safety issues (See my posts on stripping cars to bare metal, and one guy wanting to use a airless sprayer to paint a car--downright dangerous.), but I would like people to really understand these topics.

I do know a lot of these wax (and I use wax, sealer, protectorant interchangeably) solutions are really hard on paints and tend to lower exterior durability. From reading the posts on this subject and doing some thinking, I do think the waterborne formulations of wax are better because you are less likely to have a solvent (or at least enough of a solvent) in the formulation that attacts the coating. The more I have thought about it, the more I think the mechanism that damages the paint the most are the solvents in these products. Now I haven't done any testing to prove this hypothesis, so I do not really know the reason. Though I think the mechanism is similar to the way gasahol attacks car finishes much more than gasoline w/o alcohol.

With my experience in dealing with issues that have come up from customers using (end customers) and testing (auto manufacturers) different waxes over the years, I would like to dispell some of the myths of the industry. This also applies to wax or other "protectorant" solutions. Most of them do not work to protect the coating. When I was in the industry, I never found one that improved exterior exposure. They do make the coating look better, but that is not the same as protecting the coating.

As I have stated before, now there may be one or more of these products that actually provides some durability benefit. I would want the manufacturer of the product to expose this material in the real world (not some accelerated test, and for heaven's sake no water beading tests--water beading is an useless method to show improved durability) with unwaxed controls. Both sets of test panels would have to be washed with mild soap and water to eliminate the benefit of washing a coating when the wax on the waxed panels would need to be reapplied. i would require more controls, but I won't bore you with more details.

The car wash formulations really did drive me crazy. A lot of them use sulfuric acid to break down the wax to allow it to be sprayed on the car in the car wash. There are very few things worse for a car than a hot sulfuric acid bath applied under pressure. When I run my car through a car wash, I always tell them not to apply the wax even if they do not charge for it.

otto huber · #10 06-19-2010, 06:17 PM

Thanks for the input guys. A couple of months ago, before I started the thread, I used the TR3 resin glaze to restore the finish. I then applied some Meguiers NXT, and the car looked good. After 2 months the finish was fading just a little so I applied Meguiers wax cleaner, buffed it out, then applied the NXT. The car looks great right now. The good news is that I didn't pick up much paint this time like I did with the TR3. I'll keep hand washing it every couple of weeks and see how she does.