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Stain-blocking primers are used to cover stains such as watermarks, nicotine (actually tar), markers, smoke, and prevent them bleeding through newly applied layers of paint. They also provide adhesion over problematic surfaces, giving better film leveling, and durability. Commonly used stain-blocking paints include acrylic and alkyd.
Low volatile organic compounds (VOCs) formulations partially or completely eliminates odor, making them safer for the environment.[ citation needed ]
However, in the United States, solvent-based products with high VOC levels still represent approximately 25% of the total market volume for interior stain-blocking primers. They continue to maintain this significant market share even though many national, regional or local legislations and initiatives concerning the reduction of VOCs have been recently established. [1]
Since their introduction to the US market in 1997, low VOC, odorless stain-blocking primers have become known for their unique combination of highly effective stain blocking technologies. These properties are traditionally associated with solvent-based products. They also display comfortable application and low odor – characteristics commonly associated with water-based products. A good primer has to be compatible with a wide variety of substrates that may be encountered in an interior situation such as: drywall, cement, concrete, plaster and spackling, wood, paneling, old paint, metals, fiberboard, etc. Very frequently, particularly in renovation work, the surfaces encountered will be covered with a variety of stains such as water-soluble types from water leaks, smoke, nicotine, inks, etc., as well as solvent soluble stains such as tar, tannin, and others.
Recently[ when? ], many states decreased the VOC limit from 450 g/L to 350 g/L limit for the specialty primers, sealers and undercoats category. As state regulatory agencies continue to introduce stricter legislation concerning VOCs, this will pose an even tougher challenge to manufacturers of solvent-based stain-blocking primers. In order to decrease the VOC of a coating, it is necessary to remove solvent from the formulation. This has the effect of increasing relative solids content (both pigment + binder) in the formulation, which has a negative effect on viscosity. Increasing resin content primarily increases high-shear viscosity and that is important for sprayability. Increasing pigment content primarily affects low and medium shear viscosities, which are important for flow, leveling, and sag resistance. When formulating a low odor, low VOC primer, if the plan is to increase the binder, then resins with lower viscosity profiles and solubility in low-odor, isoparaffinic solvents are needed.
Low-odor, isoparaffinic solvent, in addition to being lower in odor than solvents typically used in solvent-based systems, also has a higher margin of safety versus stronger solvents. The following discussion on Air Change Index (ACI) illustrates that less air turnover is needed when using low-odor, isoparaffinic solvent in comparison to other solvent-based systems such as alkyds.
The indoor use of solvent-based primer results in increased solvent exposure due to build-up of fumes in the air. One way to reduce the amount of solvent in the air is to use fans to renew the air. The Air Change Index (ACI) of a solvent is an indication of the margin of safety of a solvent. The lower the ACI, the less air turnover needed. [2] [3]
The ACI is calculated based on the amount of solvent in the primer, the volume of the room to be primed, the volatility of the solvent and the amount of primer to be applied. The calculations were made based on a 3,500 square feet (330 m2) room and primer with coverage of 375 ft2/gallon. The below calculated ACIs were done on solvent-based primer containing 350 g/L of solvents and the water-based primer containing 50 g/L of butyl glycol.
The values on this chart indicate that the use of mineral spirits based primers would need 6 to 7 air changes per hour requiring significant ventilation. The use of low-odor, isoparaffinic solvent-based primers would only need 1 to 2 air changes per hour. Finally, the use of water-based primers would need less than 1 air change per hour. Another way to interpret this information is that the margin of safety is 3 to 4 times higher with low-odor, isoparaffinic solvent than with mineral spirits, and 5 to 6 times higher than with toluene. However, proper ventilation is still good practice with any type of primer.
Stain-blocking primers with low-odor, isoparaffinic solvent are considered to have less of a negative impact on the health of paint contractors and building residents. Despite the lower levels of VOCs, application, coverage and overall performance are comparable to their high VOC counterparts.
Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many colors—and in many different types. Paint is typically stored, sold, and applied as a liquid, but most types dry into a solid. Most paints are either oil-based or water-based and each has distinct characteristics. For one, it is illegal in most municipalities to discard oil-based paint down household drains or sewers. Clean-up solvents are also different for water-based paint than they are for oil-based paint. Water-based paints and oil-based paints will cure differently based on the outside ambient temperature of the object being painted Usually, the object being painted must be over 10 °C (50 °F), although some manufacturers of external paints/primers claim they can be applied when temperatures are as low as 2 °C (35 °F).
A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar molecules and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within the cell.
Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give low viscosity liquids. Waxes are insoluble in water but soluble in organic, nonpolar solvents. Natural waxes of different types are produced by plants and animals and occur in petroleum.
Dry cleaning is any cleaning process for clothing and textiles using a solvent other than water.
Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in various shades.
In metallurgy, a flux is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time. They are used in both extractive metallurgy and metal joining.
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula (CH3)2SO. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and is miscible in a wide range of organic solvents as well as water. It has a relatively high boiling point. DMSO has the unusual property that many individuals perceive a garlic-like taste in the mouth after DMSO makes contact with their skin.
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula (C
2H
5)
2O, sometimes abbreviated as Et
2O. It is a colourless, highly volatile, sweet-smelling, extremely flammable liquid. It is commonly used as a solvent in laboratories and as a starting fluid for some engines. It was formerly used as a general anesthetic, until non-flammable drugs were developed, such as halothane. It has been used as a recreational drug to cause intoxication.
A topical medication is a medication that is applied to a particular place on or in the body. Most often topical administration means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes including creams, foams, gels, lotions, and ointments. Many topical medications are epicutaneous, meaning that they are applied directly to the skin. Topical medications may also be inhalational, such as asthma medications, or applied to the surface of tissues other than the skin, such as eye drops applied to the conjunctiva, or ear drops placed in the ear, or medications applied to the surface of a tooth. The word topical derives from Greek τοπικόςtopikos, "of a place".
White spirit or mineral spirits, also known as mineral turpentine (AU/NZ), turpentine substitute, and petroleum spirits, is a petroleum-derived clear liquid used as a common organic solvent in painting. There are also terms for specific kinds of mineral spirits, including Stoddard solvent and solvent naphtha (petroleum). Mineral spirits are often used as a paint thinner, or as a component thereof, though paint thinner is a broader category of solvent. Odorless mineral spirits (OMS) have been refined to remove the more toxic aromatic compounds, and are recommended for applications such as oil painting.
A primer or undercoat is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.
A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. Edible thickeners are commonly used to thicken sauces, soups, and puddings without altering their taste; thickeners are also used in paints, inks, explosives, and cosmetics.
Hot-melt adhesive (HMA), also known as hot glue, is a form of thermoplastic adhesive that is commonly sold as solid cylindrical sticks of various diameters designed to be applied using a hot glue gun. The gun uses a continuous-duty heating element to melt the plastic glue, which the user pushes through the gun either with a mechanical trigger mechanism on the gun, or with direct finger pressure. The glue squeezed out of the heated nozzle is initially hot enough to burn and even blister skin. The glue is sticky when hot, and solidifies in a few seconds to one minute. Hot-melt adhesives can also be applied by dipping or spraying, and are popular with hobbyists and crafters both for affixing and as an inexpensive alternative to resin casting.
An alkyd is a polyester resin modified by the addition of fatty acids and other components. Alkyds are derived from polyols and organic acids including dicarboxylic acids or carboxylic acid anhydride and triglyceride oils. The term alkyd is a modification of the original name "alcid", reflecting the fact that they are derived from alcohol and organic acids. The inclusion of a fatty acid confers a tendency to form flexible coatings. Alkyds are used in paints, varnishes and in moulds for casting. They are the dominant resin or binder in most commercial oil-based coatings. Approximately 200,000 tons of alkyd resins are produced each year. The original alkyds were compounds of glycerol and phthalic acid sold under the name Glyptal. These were sold as substitutes for the darker-colored copal resins, thus creating alkyd varnishes that were much paler in colour. From these, the alkyds that are known today were developed.
Pressure-sensitive adhesive is a type of nonreactive adhesive which forms a bond when pressure is applied to bond the adhesive with a surface. No solvent, water, or heat is needed to activate the adhesive. It is used in pressure-sensitive tapes, labels, glue dots, stickers, sticky note pads, automobile trim, and a wide variety of other products.
Automotive paint is paint used on automobiles for both protective and decorative purposes. Water-based acrylic polyurethane enamel paint is currently the most widely used paint for reasons including reducing paint's environmental impact.
Insufflation is the act of blowing something into a body cavity. Insufflation has many medical uses, most notably as a route of administration for various drugs.
The environmental effects of paint can vary depending on the type of paint used and mitigation measures. Traditional painting materials and processes can have harmful effects on the environment, including those from the use of lead and other additives. Measures can be taken to reduce its environmental effects, including accurately estimating paint quantities so waste is minimized, and use of environmentally preferred paints, coating, painting accessories, and techniques.
Waterborne resins are sometimes called water-based resins. They are resins or polymeric resins that use water as the carrying medium as opposed to solvent or solvent-less. Resins are used in the production of coatings, adhesives, sealants, elastomers and composite materials. When the phrase waterborne resin is used it usually describes all resins which have water as the main carrying solvent. The resin could be water soluble, water reducible or water dispersed.