Priming is more than simply preserving the material; it is also about establishing a sturdy exterior for your paint. In this situation, your substrate is clay, and it should be primed with gesso (preferably). The purpose of priming is to give the piece a solid foundation to build upon. Sealing the piece is also important in preventing moisture from penetrating the paint job.
Clay can be painted over other materials such as wood or metal. However, since these substrates are porous, they will absorb some of the paint causing it to come off later. To prevent this from happening, you should prime any exposed surfaces of the piece with gesso.
Air-dry clays require special handling because they are very fragile. If you are working with dry clay, wear plastic gloves when handling it so you do not damage its surface. Also, put your clay on a sheet of paper or cardboard to keep it from drying out while you are working on other elements of your project.
Clay needs to be cured in order to use it for projects. Curing clay allows all of the water to evaporate out of it which hardens it up slightly. There are two ways to cure your clay: either heat it or expose it to air conditions. If you plan to paint or mold your clay soon after making it, heating it is the best option.
It is advised to prime the texture before painting to achieve better results. The look of the surface worsens when it is not primed. If in doubt, follow the texture manufacturer's directions, since some instructions do not need priming.
As a primer, paint should not be used. Primers are designed particularly for adhesion and sealing. Self-priming and paint-and-primer in one product is nonsense. Years ago, applying primer to paint for colors that didn't cover was referred to as a "split coat," which functioned as our first layer but did nothing for priming. Today this practice is not recommended because it is thought to weaken the paint film.
The best way to ensure good adhesion is to choose a primer that matches the paint you are applying it to. This means white or very light colored paint will require a different type of primer than an oil-based color. It is also important to allow enough time for the primer to dry before applying another layer of paint.
There are two types of primers: organic and inorganic. Inorganic primers such as zinc or titanium produce a hard finish that can look good on its own but will not seal well against water damage. Organic primers such as those containing polymers or latex reduce the reflectivity of the surface being painted and help seal the paint job from weather factors and contaminants.
Latex paints contain additives to make them more durable and flexible. These include rubber chemicals, plasticizers, and extenders. Latex paints tend to be less toxic than other types and are considered green because they're environmentally friendly. They do not evaporate into the atmosphere, so they leave no residue.
A stain-blocking primer covers over mold spots and other blemishes, preventing them from appearing through the final layers of paint. A primer applied to stone, metal, and many wood surfaces is required for optimal paint bonding. The primer also helps to protect against corrosion of metals such as iron and steel.
Organic primers are based on natural products such as linseed oil or soybean oil. These organic primers provide excellent protection for wood surfaces but can be difficult to apply effectively due to their viscosity. In addition, they may require additional treatments under high humidity conditions. Inorganic primers are made from minerals such as silicon dioxide or zinc oxide. They tend to be less expensive than organic primers and don't require any additional treatments after application.
Organic primers can be classified by type. Nail polish remover is one type of organic primer. It's easy to apply and removes most surface contaminants including old stains. However, it doesn't cover very well so you'll need multiple applications. Acetone is another type of organic primer. It provides better coverage because it's thinner and will dissolve older stains. It's best used as a final step after sanding and wiping away all dust with a clean, dry cloth.
Inorganic primers can be classed by brand.
A: All naked wood should be sealed. The finest primers are oil-based or shellac-based. A quality exterior primer has a thicker build, so if your paint job will be subjected to harsh weather wear and tear, applying an excellent primer over paint will assist hide tiny defects or cracks. If your house is older and may not have an internal wiring system, have a licensed electrician inspect the area before you begin work. He or she can advise on whether any parts of the house are electrified and point out any hazards relating to electricity.
You can also prime painted wood if there is enough time between applications. This is called a "wet" prime. Apply two coats of primer, allowing each coat to dry completely in between applications. It's important not to skimp on the primer when painting wood; if anything, it needs more coverage for protection.
If you plan to use an oil-based product as your final finish, then you should only wet-prime with an oil-based product. Water-based products are used as a surface treatment rather than as a final finish.
Wet-priming is done by covering the entire surface with a thin layer of paint. The primer is allowed to dry for several hours or overnight. When it is time to apply the second coat, water is applied to the surface until it begins to bead up. The object is to get a consistent thickness of primer throughout the project.
Prior to painting, outdoor wood surfaces should have no more than 15-20% moisture present, while interior surfaces should have 12-15% moisture present. If you decide to paint raw wood, you should first use a shellac-based primer to seal any knots (spot prime). Primers based on shellac are excellent for sealing wood knots and sap streaks. They will also help raw wood retain its color. When painting raw wood, it is best to use two coats of paint, with at least an hour in between coats.
If you want to get the most out of your paint job, then you should consider using a semi-gloss or gloss finish. These types of primers allow for more shine than a flat or dull coat, which is perfect if you plan to wax or polish your painted surface later on.
It is important to remember that wood is made up of many different types of materials that affect how it reacts to products used to finish it. The type of wood you are working with will determine what type of primer you should use. For example, if you were to paint raw cedar siding, you would need to use an amino resin primer instead of standard oil-based primer. The cedar is too acidic for normal oil-based products to work well on it. With this understanding, you can see that choosing the right primer is very important when finishing wood projects.