Conservar Polymeric Varnish
Conservar Isolating Polymeric Varnish is a colorless, reversible varnish made with an acrylic resin dissolved in a common organic solvent with UV stabilizer.
Conservar Polymeric Varnish is a colorless, reversible varnish made with a methylacrylate (Paraloid B-72) resin dissolved in a common organic solvent with UV stabilizer. It can be used both as an isolating varnish and a final varnish. The varnish can be removed with suitable solvents.
Paraloid B-72 (formerly called Acryloid B-72 in the United States) is a thermoplastic acrylic resin, provides an excellent varnish of hardness, adhesion and film toughness together with clarity and transparency. Paraloid B-72 acrylic resin can be dissolved in toluene, xylene, selected esters, acetone, and methyl ethyl ketone. Paraloid B-72 is not soluble in most alcohols and aliphatic hydrocarbons as the sole solvent. Paraloid B-72 has been used since the 1950s in conservation as a consolidation agent and as a picture varnish. Extended tests have shown it to be one of the most stable resins used in the conservation of works of art. While some change of the resin occurs after it has aged, this change can be essentially eliminated by the addition of a UV stabilizer, which is included in Conservar Polymeric Varnish.
Paraloid B-72 is insoluble in almost all purely aliphatic solvents, such as odorless mineral spirits, making it an ideal isolating varnish. It can be used with other varnishes applied as a distinct layer, for example, below Conservar Finishing Varnish or other varnishes. Conservar Finishing Varnish remains easily removable without harming the Conservar Polymeric Varnish in the layer below. Conservar Polymeric Varnish can also be used as a final varnish that is less glossy than Conservar Finishing Varnish.
Conservar Polymeric Varnish is a medium gloss varnish that has the potential for providing good saturation on many paintings. It may not provide satisfactory saturation on paintings that are dark in value. Compared to natural resin varnishes, such as dammar, Conservar Polymeric Varnish has a slightly satin-like appearance. It will not saturate colors as well as dammar or Conservar Finishing Varnish and is considerably less glossy.
Paraloid B-72 resin in Conservar Polymeric Varnish is a polymeric resin (high molecular weight) giving it a pleasant feel or ‘brushability’. When brushing it has enough viscosity to give a feeling of control while it easily spreads out evenly. Its major advantage is its relatively good leveling in a single application without the tendency to sink into matte areas of a painting.
Open working time of Conservar Polymeric Varnish is of short duration. Open working time may be extended somewhat by the addition of slower evaporating aromatic solvents. Conservar Polymeric Varnish that is brush-applied under normal conditions is generally dry to the touch within 5–10 minutes. The addition of slower drying solvents will lengthen the drying time, or the addition of acetone will shorten the drying time. As with any varnish, temperature and relative humidity will also affect drying time.
Conservar Polymeric Varnish is recommended as both an isolating and a final varnish on the following paint films:
Conservar Polymeric Varnish is specifically formulated to be applied over copper or as a varnish on acrylic, oil or alkyd paintings.
A four fluid ounce (118 ml) can covers approximately 50 square feet (4.6 square meters).
Prior to actual use, it is very important to test Conservar varnishes on test pieces to understand how they perform and how they alter the surface appearance of your paintings. For best results, apply to a test piece that is similar in composition as the artwork to be varnished. This will help ensure that a successful varnish application will be achieved.
When to Varnish
The best practice is to wait 6 to 12 months before varnishing with Conservar Polymeric Varnish. Oil and alkyd paint films need time (typically months) to polymerize and form a resilient film otherwise a coating added on top of an improperly cured film may cause the layers beneath to swell and loosen.
It may be possible to apply Conservar Polymeric Varnish when the thickest areas of your painting are “dry through”—not touch dry. To determine if your painting is “dry-through”, press into the thickest area of your painting with your thumb at the same time twisting it a full 90° on the paint film. If your painting is on a flexible support, such as stretched canvas, be certain to provide support to the opposite side. The paint is considered dry-through when there is no loosening, detachment, wrinkling, or other of distortion visible on the paint surface. This procedure is fully described in the ASTM Standard D1640: Standard Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room Temperature.
Please note, however, that the more the oil/alkyd paint is allowed to polymerize or cure the more likely the varnish application will be successful. Always test the application of varnish on test pieces first to determine the suitability of the varnish for your application.
Preparation for Varnishing
Acclimate painting and varnish materials and tools to the same environment. At least several hours prior to varnishing, place all items, such as your painting, brushes, containers, and Conservar varnish, in the same room. Varnish in a dust-free environment with the least amount of air movement to avoid raising dust.
It is best to brush or spray apply Conservar varnishes. Other methods, such as applying with paint pads, sponging or rolling, are not recommended, as they may result in foaming, loss of film clarity, non-uniform coverage, excessive film build, sagging, or deposit of materials from the application tool.
Apply with a wide flat, stiff-hair brush. Conservar Polymeric Varnish can be thinned up to 20% with acetone or toluene. DO NOT MIX WITH WATER. Apply only one coat as a final varnish when applying by brush. Allow to dry three days and wipe varnished surface with a soft, lint-free cloth.
The best way to achieve an even coating of varnish is to apply by spraying. This is particularly true for impasto surfaces. Spraying is also a useful technique for creating a matte surface. The size of the surface to be sprayed will determine the best type of spray equipment to use. Conservar varnishes can be sprayed from an airbrush, airless or air-pressure spray equipment, or refillable aerosol spray can.
To prepare for spraying, make sure all equipment is free of dirt. Work in an area free of dust and dirt and keep work off the ground when spraying. Spray two to four light even coats instead of one or two thicker applications, allowing enough time for drying between coats (1 to 4 hours or until the surface is tack free).
Release the spray trigger when stopping the motion of the sprayer during application in order to avoid a buildup of varnish in one spot. Maintain a uniform distance from the surface, and avoid spraying in an arcing motion. Make straight passes across the work, changing direction once the spray has cleared the edge of the piece being varnished. Slightly overlap the spray pattern with each pass, until the entire passage has been covered.
To achieve a more uniform spray application, turn the painting 90 degrees and apply the subsequent coat perpendicular to the previous one. A typical spray application lays down a film only 1/8 to 1/4 the thickness of a brush coat application. If maximum protection is required of the varnish layer, apply multiple coats.
When applying multiple coats (spray application only), allow 1 to 4 hours in between coats. Inspect the surface for tackiness, which may mean that the coat is not sufficiently dry. Let the varnish cure several days before packing or transporting the painting. During transportation and storage, avoid contacting the surface with packing materials, including glassine, bubble wrap or any other plastic. NEVER STACK PAINTINGS, whether varnished or not.
Care and Storage
As Conservar varnishes are removable, it is important that they not be painted over. Paint applied over the varnish would also be potentially removable, and would pose a difficult problem in conservation or restoration attempts.
Techniques for Reducing Gloss
There are a number of different ways to reduce the gloss of Conservar varnish:
- Dilute the varnish with additional solvent before using.
- Apply a thin coating. The thinner the coating, the lower the gloss.
- Brush the varnish as it dries. When the varnish is starting to set up, if you continue to brush it then you will microscopically roughen the surface and it will be less glossy.
- Spray apply the varnish.
If the varnished surface of your painting appears too glossy, you can apply a final coating of Conservar Wax. Rub on a thin layer of wax with a soft, lint-free cloth using small circular strokes. Allow the wax to dry overnight for the highest degree of matte. To create a satin finish, allow the wax to dry for about 4 to 6 hours, and then gently buff.
Clean all equipment immediately following application. Clean brushes with the recommended acetone. To ensure desired results, always make a test piece for your particular application and surface.
Use a clean, soft, lint-free rag dampened with xylene. Xylene is a strong solvent so care must be taken when using it. Gently rub the varnished surface and repeat process until all varnish is removed. Allow to dry and reapply Conservar varnish. The solvents used to remove Conservar as opposed to those used for natural resin varnishes are less likely to damage paint films during the cleaning process. Conservar Polymeric Varnish is not an easy varnish to use but with practice you can produce an aesthetically pleasing varnish layer.
Paraloid B-72 is a registered trademark of Dow Chemical Corporation. Conservar is a trademark of Natural Pigments. Rublev Colours is a registered trademark of Natural Pigments.
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Signal Word: Danger
Propylene glycol methyl ether
Flammable liquid and vapor.
Causes skin irritation.
Causes serious eye irritation.
May cause genetic defects.
May cause cancer.
May cause respiratory irritation.
May be fatal if swallowed and enters airways.
If medical advice is needed, have product container or label at hand.
Keep out of reach of children.
Read label before use.
Keep away from heat/sparks/open flames/hot surfaces. No smoking.
IF SWALLOWED: Do NOT induce vomiting. Immediately call a POISON CENTER or a physician.
IF ON SKIN (or hair): Immediately take off all contaminated clothing. Rinse skin with water.
IF INHALED: Remove person to fresh air and keep comfortable for breathing. Call a POISON CENTER or a physician if you feel unwell.
IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Conforms to ASTM D4236.