Do I need to prime the car before puttying?
Content
Putty - a composition that has a plastic form and is designed to fill the cavities formed due to damage to the element. Due to the peculiarities of the action of primer and putty mixtures, the order of their application differs - first, large defects are eliminated, then the composition is distributed, which ensures reliable adhesion of the paint and the treated surface.
When doing body repairs on their own, some motorists do not know the correct sequence of actions, doubting whether a primer or putty is first applied to the car. We will find out in what order professionals process the car body.
Differences between primer and putty
The main purpose of the primer is to improve adhesion between applied layers of paintwork (LCP). In addition, it performs other functions:
- Removes air bubbles from small defects of the treated surface (scratches, chips, invisible to the naked eye).
- Serves as a connecting component for layers that are poorly compatible with each other and can enter into a chemical reaction, subsequently exfoliating.
- Protects from external influences - contact with water, air, sand and other substances. Due to the fact that the primer prevents external access to the metal, the formation of corrosion is excluded.
Putty - a composition that has a plastic form and is designed to fill the cavities formed due to damage to the element. Due to the peculiarities of the action of primer and putty mixtures, the order of their application differs - first, large defects are eliminated, then the composition is distributed, which ensures reliable adhesion of the paint and the treated surface.
Car body priming
Do I need to prime before puttying
The technology of processing body parts before painting does not involve priming before using putty. The troubleshooting composition is intended for application to "bare" metal, good adhesion is achieved by adding special components to it.
Priming a car before puttying is allowed only if the mixture contains epoxy. Painters do this when carrying out long-term repairs of body parts. Most often, restoration and restoration work takes a long time. When the metal is exposed to the open air, in conditions of high humidity, corrosion processes are activated.
It is allowed to prime the metal before puttying the car until it is completely dry. The components that make up both tools interact with each other and are tightly connected. To improve adhesion, the surface is lightly cleaned by removing protruding elements.
Whether it is possible to put putty on old LKP
Puttying old paint makes sense when there is concern about the appearance of corrosion a short time after treatment. To improve adhesion, it is recommended to treat the paintwork with sandpaper, giving it porosity. The putty will subsequently penetrate into these pores and stick firmly.
The procedure for applying putty on the old paintwork:
- Clean the surface to be treated in problem areas - remove swollen paint, bituminous stains, etc.
- Degrease the body element with a solvent, alcohol.
- Repair existing defects.
It is possible to apply the putty composition only on paint that is in good condition - it does not have cracks, chips, or flaking. If there are defects in large quantities, it is better to clean the old paintwork to a metal surface.
How to choose the right putty, application features
The putty composition is selected depending on the problem of the processed body element. Types of putties differ from each other in the active ingredient:
- Fiberglass. They are used to eliminate large defects, since fiberglass fibers have a rough structure, require subsequent grinding and applying a finishing layer. Such material is characterized by the formation of a rigid fixing area, which is resistant to damage even under heavy load.
- With large grains. Used for rough treatment of areas with significant damage. Differs in plasticity and well puttied hard-to-reach places. Due to the presence of large components in the composition, the primer does not shrink and is characterized by increased adhesion.
- With fine grain. Some painters call it finishing, as it is used to repair small defects. The fine-grained primer is easily processed with sandpaper, there are no scratches or other visible defects on the surface. The primer is suitable for filling not only metal, but also plastic, fiberglass elements.
- Based on acrylic. The structure does not resemble the usual putty - the acrylic composition is liquid, in appearance it resembles a primer. It is used for filling large areas, it is plastic and easy to apply. The manufacturer of the product allows painting the treated surface without subsequent priming.
The procedure for applying the putty composition:
- Clean the surface.
- Coarse-grained (fiberglass) filler is placed in large pores.
- Fine-grained or acrylic putty removes minor defects.
- Primed and painted bodywork.
How to choose and apply a primer
Before applying, you need to study the types of primer mixtures, since the scope of their application varies depending on the purpose.
How to grind primer
Soil types:
- Epoxy based. It is characterized by a liquid structure, as well as the content of chromium. Differs in resistance to influence of aggressive chemical compounds, interferes with formation of a rust. Epoxy primer does not require additional stripping before painting (except when the composition was applied inaccurately and streaks formed).
- Primary. The main purpose is anti-corrosion protection of areas subject to direct contact with water. It is allowed to apply a primer before puttying the car.
- Sealed. It eliminates contact between two layers of paint and varnish and does not allow the negative impact of one on the other (the paint may contain aggressive chemical compounds that destroy the putty).
Ground application procedure:
- Clean up visible defects on the putty by removing protruding elements.
- Degrease the treated surface with a solvent, alcohol, gasoline.
- Apply a primer in several layers, between each it is required to take a break of at least 90 minutes to dry.
You can determine whether the next layer has dried by its appearance - it will become dull and a little rough.
Which is better - priming or puttying a car
A similar question is asked by beginners in the painting business. They do not fully understand the purpose of both compositions and do not see the difference in functionality. Although some primer manufacturers allow their use on bare metal, not every product can eliminate existing paintwork defects. Filling large craters without the use of putty is impossible, therefore, when selecting a filler for processing each body element, it is necessary to approach it individually.
