Repair with their own hands: how to paint to avoid rust after the first winter?
This question is often asked in different forms by the owners of used cars, do-it-yourself repainting their cars “at knee”, and entrusted this business to garage or esthetician professionals. What is there, not without sin: in olden days, when I was not engaged in complete restoration of “squatters” and did not delve into the nature of corrosion, I often wondered about this question. Why do cars, like everything made of metal, rust? Why after the painting this plague often appears again and again, no matter what you do with it? Popular wisdom on the subject says: “Rust is a cancer of metal, if it appeared – it will spread, even if you burst” (“O’key Google!”).
At my time, not having found a ready answer on the Internet and from my fellow car painters, I had to start from theoretical basics. Having carried out a number of experiments on corrosion preservation with subsequent observation of “patients”, I can give an accessible explanation of this process and methods of combating it.
“Corrosion, rust, rust is the spontaneous destruction of metals as a result of chemical or physical-chemical interaction with the environment.
It is schematically depicted as follows:
Humanly speaking, iron molecules interacting with oxygen and water molecules yields iron hydroxide Fe(OH)3 (rust).
Well, everything is clear with the question “who is to blame?”, now it remains to understand “what to do?”.
The answer: the only way to protect yourself from rust in the long term – is to carry out a set of measures aimed at the removal of the actual corrosion (rust), followed by preservation of the affected area from the effects of oxygen and water.
1. It is necessary to remove the rust by mechanical method.
a) Sandblasting.
From myself I will say that for local scraping of small “bugs” quite fit household compressor for 220 V with sandblasting “pistols” for 400.000-500.000 Belarusian rubles.
I note that a full-fledged sandblasting to build in a garage without the presence of 380 V almost unrealistic.
b) Mechanical method. Vinyl nozzles like 3M Scotch-Brite Clean’n’Strip™ and their budget analogs are ideal for this.
The nozzles are available in options for attaching to the “grinder” and to the drill (with a simple adapter, which is popularly replaced by a bolt, nut and a couple of washers) and literally “chews out” the corrosion from the whole metal. Use metal “brushes” and “cups” for such work is categorically impossible! Despite the beautiful shiny metal left after their work, in fact there is “licking” of corrosion by the whole metal. It is enough to rub the treated place with a “brush” with an “emery cloth” to make sure that my words are true – red spots will appear from under the shiny metal.
Regardless of the cleaning method you choose, the affected area must be treated with the chemical method (rust converter) with (attention. ) obligatory washing out of the converter with a solution of water and soda. Only in this way you can neutralize the acid contained in the converter. If you don’t do this, the remaining acid will start to “eat” the whole metal if you continue to get water on the spot.
Personally, I prefer to remove rust using the electrochemical method rather than the physical method.
c) “Okay Google, show me again “how the electrochemical method of rust removal works”.
Briefly: a small amount of soda ash (sold in hardware stores) is poured into water, the part to be cleaned and the electrode (an unwanted piece of metal) is put down. After 12 volts minus is given to the cleaned item, 12 volts plus is given to the electrode, and depending on current strength (it is convenient to take an old power supply from computer as a power source) and the area of the item and electrode after 1-12 hours all the rust practically magically goes to the electrode. All that remains is to wash the part to be cleaned and clean it of traces of former rust at least with an iron brush.
The application of this method is, in fact, limited by the volume of the vessel used to lower the part and the availability of space to install this vessel.
And if, say, a brake caliper can be cleaned in a plastic bucket installed on the balcony of an apartment, then for cleaning of a door or a hood you will need a container like “Eurocube”.
Alas, even so, complete bodywork will remain only in dreams. Though I know cases when improvised “bathtub” was made at summer house from crates and banner fabric and made full-fledged stripping of dismantled frame of SUV.
2. If there are several pockets of corrosion you need to remove all the coating from the element. Yes, yes, how is unfortunate, but if you want to protect your 10-15-year-old car from corrosion or to prolong the life of the repair coating, you need to clean up at least some of the body element, and then make conclusions.
Under the paint is often already “live” a lot of nascent “bugs” that in a season or two will declare their existence.
3. Further, all work on the surface (after the initial wash or wash after the electrochemical method) should be carried out without water. This is done to avoid moisture contact with the cleaned metal or (what is the most dangerous) retention of some moisture in the applied layers of the material. Because we know from the school course that moisture expands when it freezes, the water that remains under the ground or in the thickness of the filler can not only cause corrosion, but also, freezing to form a microcrack in the coating with the following direct access of water and oxygen to the precious surface that we protect.
And the most important point – how to protect the metal after stripping from rusting again, or at least slow down the process, stretching it for years. There is a special anticorrosive epoxy primer for this purpose.
Remember: only epoxy is impervious to molecular water. All other types of coatings (acrylic primer, which, in fact, is only a filler, designed to level the surface and does not play any anti-corrosion role, acrylic paint, base paint, varnish, etc.) allow water molecules to pass through to varying degrees.
In fact, all waterborne paints and coatings are analogous to mosquito netting, only the pore cells of all types of coatings are different in size. Epoxy has the smallest mesh size.
If to summarize the above 4 points, you can understand the technology to protect the car body as a whole and from local “bugs”, which may in different variations suit the average car owner, thinking how to remove the “bug” from the arch, as well as car paint shop, wishing to give a guarantee on their work not for the standard 6 months, but 3-4 years or more!
Technology for car services (for 10 years old cars and older): bare metal, cleaned according to technology – acrylic primer – filler – puttying – acrylic primer and primer development – correction of puttying flaws – epoxy primer and acrylic primer (technology “wet on wet”) – prepainted trowel (if we paint not “wet on wet”) – painting.
Technology for the average car owner: grind the “bug” vinyl wheel on a drill, process the converter rust, rinse the converter with water with the addition of soda – dry – grind “sandpaper” – apply a layer of epoxy – painted in color cars at least with a brush.
Variations between these two options everyone can do on the basis of their technical capabilities.
With all simplicity of suggested method, I almost forgot to share with you a small but. You know, it’s like in the joke about how a Chinese copy differs from the original: in fact, a copy looks and looks exactly the same as the original, and is designed like him, but the Chinese copy does not work like the original.
So it is here: any more or less deep corrosion, destroying the metal, forms micro-pores in its thickness, which can “feed” oxygen and moisture from the reverse side of the body metal, so treating one side of the “bug”, do not forget about the other side! Unfortunately, it is not always possible to access it, but at least antiquing the repair spots on the back side is necessary, but that’s another story!
If you think the question is answered in details, speak up in the comments, and tell how you personally struggled with corrosion and how it ended.
P.S. I hope, now you understand the reason, why on the painted pieces in the first winter of rust from under paint creeps, why most of the painting services prefer to give a 6-month warranty on their work? I can add that made by this technology, even the “old” Soviet cars 3-4 years or more after the painting maintains the appearance with the complete absence of corrosion (with the timely elimination of chips coating), in fact my “Volga” live example.
Sergey ZHILTSOV Photos from the author’s archive and open sources
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Car body rust removal with your own hands.
The bodies of all cars are subject to corrosion, but it is possible and necessary to fight with it. In this article I will tell you how to get rid of rust on the body of your favorite car on your own, and, thereby, prolong its life and improve its appearance. I will tell and show you everything by the example of my own repair. Did it all for the first time and it turned out very well. So, I think, any motorist can repeat this and save a lot of money on body repair. So, let’s begin…
For repair you will need:
– Sandpaper large (120) and small (400 and 600); – Brushes on metal, but it is better a grinder or an electric drill with a special nozzle; – Degreaser; – Rust converter (Cincar) – Putty with fiberglass; – Putty ordinary; – Primer anticorrosive in a can; – Paint in a can; – Painting tape and more newspapers; – Clean rags for degreasing;
This is what my car looked like before the repair:
Before you start, you need to give the car a good wash so you can see all the damaged areas. Once you have washed the car and have everything you need ready, you can begin.
1. clean the surface well from rust and old paint. It is desirable to use for this purpose a grinder or an electric drill with a special attachment, this will save you a lot of time and effort, and the repair will be of higher quality.
If you are a pauper and don’t have a grinder or a drill, you should clean everything by hand (I had to do this because the grinder burned out almost immediately) using a coarse sandpaper and a metal brush. Be careful when sanding the surface with coarse sandpaper. It’s better to use no coarser than 120 grit sandpaper. I used 40 at first and made scratches which are visible even after painting.
2. 2. Wipe and degrease the cleaned surface.
Apply a rust converter to the cleaned surface. This is needed to eliminate rust at the chemical level and remove it completely. 4.
4. degrease.
5. Apply a fiberglass filler to fill large dents or holes from corrosion. After it has dried, smooth it out with coarse sandpaper. It is not completely level because it is used to fill in large irregularities, as a base for normal putty. Important! Try not to scratch the body while working with coarse sandpaper!
6. Degrease
7. Apply ordinary putty. After it dries, sand it to an even surface with an emery.
8. Degrease .
9. Places that will not be painted over with masking tape and newspapers.
10. Apply anti-corrosion primer I applied it from a spray can in three layers. The 1st coat is the thinnest, the 2nd thickest and the 3rd final coat is the greasiest. Between coats you need to wait 10-15 min. so the primer has time to dry. To apply the primer well it is necessary to hold the can at a distance of 20-25 cm from the surface and move it horizontally. If there is not much rust on the body, you can not putty, and immediately apply the primer and paint.
11. mat the primer with a wet 600 sandpaper. It is better to soak the sandpaper in water for about 5 minutes. Next we wait when the surface dries.
12. degrease.
13. Painting. To paint well and without a trickle it must be applied from a distance of 20-30 cm and move horizontally. I painted in 4 layers, each subsequent layer is more greasy than the previous one. Between coats I paused for 15-20 minutes to dry the paint. Do not forget to shake the can with paint periodically during the painting process.
