The primary ( ) or bottom layers are preparative layers attached to the material before drawing. Priming ensures better paint adhesion to the surface, enhances paint resistance, and provides added protection for the painted material.
Video Primer (paint)
Composition
Primer consists of 20% -30% synthetic resin, 60% -80% solvent and 2% -5% additive. Some primers contain polyethylene (plastic), for better durability.
Maps Primer (paint)
Use
Primary is a paint product that allows the final paint to comply much better than if used alone. For this purpose, the primers are designed to adhere to the surface and form a better bonding layer prepared to receive the paint. Since primers do not need to be engineered to form a long-lasting surface, they can be engineered to improve the properties of binding and binding to the underlying material. Sometimes this is achieved by chemistry, as in the case of primary aluminum, but more often it is achieved through controlling of primary physical properties, such as porosity, adhesiveness, and hygroscopic.
In practice, primers are often used when painting various types of porous materials, such as concrete and especially wood (see detailed description below). Priming is mandatory if the material is not water-resistant and will be exposed to elements. Priming gypsum board (drywall) is also a standard practice with new construction due to wall seal and helps prevent mold. Primers can also be used for dirty surfaces that can not be cleaned, or before painting light colors over existing dark colors.
Primer can usually be colored with a color near the final paint. If paint finishing is a deep color, primary dyeing can reduce the number of final paint layers required for good uniformity throughout the painted surface. Primers are also used to hide connections and stitches to give the final look.
There may be a maximum time frame in which the topcoat should be applied on top of the primer after the primer dries, to achieve maximum performance. Depending on the primer, the next layer of paint should be applied as fast as 24 hours or for two weeks. Painting after the suggested time frame can cause performance problems depending on the specific situation. Painters often apply a final coat of paint before the cure completely cures to improve the adhesion of the top layer to the primer. If the top layer is applied after the suggested time frame, consider using the top layer "self priming". For a definitive answer on the recommended redemption time frame, check the primary label/website, or contact the manufacturer directly. Time-frame recoats are most likely a more important factor in exterior applications due to more extreme climatic exposure.
On wood
Using primers on wood before painting is important for several reasons. First, the wood is very porous and will absorb the solvent from the paint, dry the paint prematurely. Since most paints undergo chemical reactions during the curing process (for example, latex-based paints and alkyds actually polymerize during the curing process), they depend on water or solvent being evaporated slowly rather than being absorbed rapidly by the underlying ingredients. The primary layer will help the paint to undergo the proper curing cycle right.
Secondly, without primer, several layers of paint can be needed to blur the wood grain and ensure color.
And lastly, if the wood is exposed to moisture, a thin coat of paint will remain a permeable water. The end result is a curved part, a fungus, and a dry rot. Primer adds waterproofing effect to the paint.
Excellent quality is often worth the price to complete the paint, their cost is influenced by the quality of the binder they use. Some special primers are actually quite expensive.
Primers are not used for wood stain treatments designed to show wood fibers. In softwood, the wood conditioner (shelled or varnish thin) allows even more uniform staining. Sealer is designed to promote a uniform end result. They are designed with a quality that promotes quick drying and they have high isocynate content that can not be sanded,
On metal
Some metals, such as unprocessed aluminum, require primers; others may not. Primers designed for metals are still highly recommended if parts must be exposed to moisture. Once water seeps into the bare metal, oxidation will begin (plain steel will only rust). Primary metals may contain additional ingredients to protect against corrosion, such as zinc casualties.
Hydroxides/metal oxides do not provide a solid surface for paint to stick, and the paint will come out in large pieces. Using a primary will provide additional insurance against such a scenario. An additional reason to use primers on metal can be a bad surface condition. Parts of steel can be corroded, for example. Of course, the best solution is to clean the metal thoroughly (blasting), but when this is not a viable option, special primer types can be used that chemically convert the rust into solid metal salt. And although the surface is still less compared to the shiny clean metals, it's still much better than weak, porous crust.
Painting and gluing of aluminum is essential in the aircraft industry, which uses toxic zinc chromate and chromate primers to add the required adhesion properties.
On plastic
Using primers on surfaces made of plastic is only necessary when making drastic color changes (going from dark to white brown, for example), since most household plastics are not very porous and are not easily damaged by moisture; or when a durable coat of paint is desired. Primer will reduce the amount of paint layer needed to completely cover the previous color, and will help the paint create a thorough bond with the painted surface. Since most paints and primers designed to be used for non-water-based plastic painting, an important point for choosing primers for plastics is to make sure the primary propellant or solvent will not dissolve or melt the plastic parts themselves (eg the most common household spray paint will damage the foam polystyrene). Both the base and paint paint should be tested at a small hidden point of the painted part.
Alternative
Alternative surface treatments, such as plasma activation, can replace primers in cases when the latter is used to enhance adhesive bonds between substrate and paint or varnish. The quality of adhesive bonds, such as varnishing and painting, is highly dependent on the adhesive ability to cover the efficiency (wet) of the substrate area. This occurs when the substrate surface energy is greater than the adhesive surface energy. However, high-strength adhesives - lacquers and paints - have high surface energy. Thus, their applications are problematic for low surface energy materials such as polymers or oxidized metals.
To overcome this problem, plasma activation is used as a preparatory step before adhesive bonding. It removes polymer surfaces from organic contaminants, removes weak border layers, reinforces surfaces with crosslinked molecules and chemically binds to a strong substrate layer with high surface energy and chemical affinity on the adhesive. In addition, plasma processing can also reduce or remove hard oxides from metal surfaces, allowing the painting and gluing of metals such as copper and aluminum. Importantly, plasma activation can be performed at atmospheric pressures in the air at rapid processing speeds. It does not use wet chemistry, which positively affects cost, safety and environmental impact.
See also
- Paint
- Aerosol paint
- Gesso
- Primary stain-blocking
References
Source of the article : Wikipedia
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