Epoxy and acid primers
Recently, questions have often arisen on the use of various primers for body repair. Let's try with you to figure out what soils are and in which case each of them should be applied.
After the hazy coat, the full coat should continue as usual with no run. The photo shows the panel mounted horizontally, but the fog layer helps even more with vertical panels. It is good to use a high quality pickling primer rather than thin versions. This will usually be a different color for later coats of high quality primer and will provide a margin for abrasion. highly loaded soil is rubbed, he is sure that the panel has been rubbed far enough, and rubbing will still expose bare metal.
Compatibility of PRIMERS in auto painting Acidic and acrylic. Interaction of primers, their area of \u200b\u200bapplication and their compatibility.
We distinguish three main types of soils:
- 2K acrylic filler or leveler
- 2K epoxy primer
- 2K acid soil
We will consider 1K epoxy-based etching primers as special ones.
Description and types of wax primers
The high fill primer is the next step after sonar priming. The high build primer adds a relatively thick coating of paint that is sandpaper, and is used to eliminate deficiencies in the panel. Usually two layers of high soil content are sufficient.
Care should be taken not to create excessive paint thickness on the edges of the doors, or they will be exposed to chips. A guide coat is a fine mist of color applied over a high strength primer and then damp and damp. Initial sanding will remove the high points, and only when all of the guide cover is removed so that the high points of the panel are flat with the low points, then the surface is completely smooth and ready for topcoat.
Acrylic 2K primer performs only a filling function and can sometimes be an insulator of one layer from another. As a rule, such soils are hygroscopic. (Hygroscopicity - vapor permeability). They do not saturate water like a sponge, but only accumulate evaporation and moisture, which then condenses upon cooling and accumulates in the form of microdroplets on the metal surface under the ground. And this moisture evaporates for a very long time, because of this, the corrosion process begins on the metal. Therefore, acrylic primers are used only for filling / leveling (pouring) putty or underlying paintwork layers.
The primer is applied just before the colored coating. My approach with a guide coat is to mix evenly with the primer and then add at least 75% thinners. The content of the primer helps to sand and thicken the guide layer so that it does not disappear before the panel is flat. The use of a top coat prevents paint problems over any guide coat that is not fully sanded.
Technology of using and processing acrylic primer
As a base for colored coatings, 600 grit blast paper is suitable. The sanding block is useful as it does not follow the local grooves on the panel, as far as hand sanding is concerned. The sanding direction should be changed frequently when block sanding. First along the panel, then up the panel, then 45 degrees, then 45 degrees the other way.
Epoxy primers are used primarily as an insulator. Such a soil does not allow water, evaporation or moisture to pass through. Also, 2K or 1K epoxy primer is the primary primer when working with metals such as aluminum, zinc, copper, etc., as well as with cataphoresis primers, as it has excellent adhesion and acts as a waterproofing agent. Epoxy primer is chemically resistant, but it is afraid of UV radiation, so you cannot store a car in the open sun after applying only epoxy primer to it.
It is very helpful to have a high primer first coat in a different color so you know when you are sanding through body filler and getting close to bare metal exposure. You have to be careful around the edges of the panel though - one emery cloth can remove the filler primer and all the self-etching in one stroke. If this happens, try a little more primer on the area and flat panel into panel without a guide coat. Edges are best hand-finished.
Do not use a wetting agent during wet sanding - it can be difficult to completely remove from the panel and can contaminate later coatings, and in any case it is not necessary for a primer. The area around the doorknob will be hidden by the handle itself, so it doesn't make sense to risk too much sanding around those sharp edges. The guide plate leaves a good flat surface for spraying colored coatings. Any paint degradation from here must be sorted out by sanding or polishing the colored coating without risk of returning back to the primer, and since the base is flat it will be possible to paint the colored coatings tightly to leave a completely flat mirror finish.
The third group of soils is 2K acid soils based on polyvinyl butyral. They are also called phosphating or reactive. These primers provide chemical adhesion and also contribute to the formation of a protective layer on the metal. Often we are unable to remove the rust completely. It still remains in the pores and microcracks. It is in this case that acidic soil is used. It converts the remaining corrosion, turning it into a phosphate film, which will further protect the metal from oxidation. Also, as a result of chemical reactions, lead or zinc is deposited on the repair surface, which are acidic soil in the form of chromates. These metals practically do not oxidize and, accordingly, reduce the likelihood of corrosion in the repair area.
It has always always happened that self-etching has to be poured with a primer as soon as it is dry. If the paint is left overnight, it can absorb moisture, which weakens the bond to the steel panel. The high quality primer forms a thick paint layer suitable for sanding. It is not suitable for direct application to bare metal.
Acid primer - special - - articles catalog - body repair
Red Oxide was effective in earlier times and was famous on the Forth railway bridge. The active ingredient is lead tetroxide, which together with other lead paints can lead to lead poisoning and has been discontinued.
When working with aluminum, galvanized surfaces, as well as with cataphoresis primers, in principle, we can use epoxy and acid primers, to whom which is closer.
Now let's consider the sore point of soil compatibility. Acrylic primer filler can be applied to both epoxy and acidic.
Acidic soil can be applied to any 2K cured coating in the event that it is not possible to apply it especially to metal.
The color red is just a pigment added by marketing people to leverage the public memory of real red lead primers. Soils that adhere well to bare metals nowadays contain zinc phosphate. The zinc in zinc phosphate primers does not offer any protection against galvanization - it is simply bound to a metal, which it does very effectively. Boat builders typically use it as a primer for superstructure, but not for diving.
Galvanized primer
For underwater protection, boat builders will use zinc primers. They will contain 90% zinc by weight and provide some degree of protection against cold zinc plating. They are available in epoxy or natural thinned. Natural thinned paint is considered to be more effective, but its adhesion is poor - sandblasting the bare metal surface is essential to provide a rough surface for the paint to stick to, otherwise it can be scraped off with your finger.
The epoxy primer can be applied to any cured 2K material. If old surfaces are undermined, this is a consequence of improper dilution, since we often use solvent 646 as a thinner, which is fundamentally wrong. You need to dilute it with your own special thinner. By the way, this is precisely why its incomplete drying is connected. The 646th solvent, rapidly evaporating, creates a surface crust, due to which the rest of the solvent cannot escape from the soil. As a result, we get "plasticine", which has to be removed with a spatula. If a set of epoxy primer comes in a 1 to 1 ratio with a hardener, then such primers, as a rule, do not need additional dilution.
Epoxy primer in particular can be applied to 2K acidic ones. And we will consider this issue in more detail.
So, I will say right away that it is possible to apply, but not recommended. Nothing will fall off or flake off. But epoxy primer dissolves acidic, even if you haven't diluted the epoxy with anything, in which case the properties of the reactive phosphating primer are lost. So there is no practical sense. In some systems, such a combination is still provided, but, at the same time, the acid must be kept for at least one and a half hours. In a polymerized (irreversible) state, after matting, it can be covered with almost any type of paintwork. But in our reality, we apply a thin layer of acid maker, as it is prone to strong shrinkage, therefore we do not have the opportunity to grind it, but cover it "wet-on-wet". In turn, the acrylic filler is absolutely neutral to acidic. So we can use acrylic as an insulator. It is applied on an acidic layer in two full layers, dried and matted in different ways, in accordance with what it will be covered with. If the next is epoxy primer, then gradation P240 or P320, if putty, then P150 or P180.
But then you ask, why putty? After all, it should be placed on bare metal? The putty must not be placed on the metal if it has not been completely removed from the rust. It is also prohibited to apply it on acidic soil, as its hardener, not surprisingly, also dissolves thinly applied acidic soil. If the acid is kept for more than an hour and a half, the putty can be applied, but again we must create a risk on the surface of the acidic soil, which is not possible, since we will simply erase it.
In the case of filling the problem area, first put an acid maker, then cover it with two layers of acrylic filler, dry it with three P150 or P180. At the same time, try to erase the acrylic primer along with the acid one. Then put putty on. After processing the putty, we put the epoxy on it in two incomplete layers with an interlayer for 5-7 minutes and after 20 minutes of exposure, we again apply acrylic in two full layers, which we then grind and prepare for painting. In principle, it is possible to paint on epoxy, but for this we will have to dry it (up to 16 hours of waiting) and then grind it with difficulty, since it will be very hard. If it is painted wet-on-wet, which is also foreseen, then it must be applied in an ideal way, which is often very difficult. It's easier to cover it with acrylic right away, since it is easy to process, fills in small risks and evens out a little.
The last type of primer we will look at is an epoxy-based 1K etch primer. They are available both in cylinders and in liter cans. They are mainly used as soils "from rubbing" or "cuts". It is applied to the exposed areas of metal or putty in 2 thin layers with interlayer drying for 4-7 minutes and after 20 minutes can be covered with most paintwork. They are also used as primers for multi-surfaces, when we have stains of various materials - metal, putty, primer, paint, etc. So we cover this entire economy with just such a soil. In this case, it helps to reduce the risk of the formation of such defects as delineation of the repair zone and material subsidence. In general, it is recommended to use it in every renovation, as an intermediate layer between putty and acrylic filler. Why? Because we often dilute the soil with a solvent, which is then absorbed into the putty, and, evaporating, in the future can lead not only to the above defects, such as contouring or subsidence of materials, but also to peeling of the base or varnish. So make sure you always have it close at hand.
I express my gratitude for the preparation of the material kapikander
2 years Tags: epoxy primer, acid primer, soil interaction, primers, painting
