Golden Acrylic Polymer Varnishes
I've been experimenting with Golden Satin Acrylic Polymer Varnish this week. This is not a permanent varnish. It's intended to go over a permanent isolation layer. The following is information taken directly from the Golden website:
PRODUCT DESCRIPTION
GOLDEN Polymer Varnish with UVLS (Ultra Violet Light Stabilizers) is a water-based acrylic polymer varnish formulated to provide additional protection from ultraviolet radiation. This helps delay the inevitable fading that occurs in materials that may be fugitive in nature.
Polymer Varnish is designed as a topcoat for acrylic paints and offers a removable protective surface to the relatively soft acrylic paint layer. It has a harder film than most acrylic paints, which diminishes the susceptibility of the surface to dust and dirt, and provides increased protection from scratching, marring and moisture. It has adequate flexibility to withstand normal handling conditions, including loose rolling. Do not use for oil paintings. For interior use only. The product is not recommended for use on furniture or other surfaces subject to physical contact during use.
Polymer Varnish remains soluble in alkaline solvents, such as ammonia. This means the varnish can be easily removed; taking with it any accumulated surface contamination without damaging the painting surface. The use of such a removable varnish provides a valuable tool to anyone trying to restore or clean a painting.
Polymer Varnish (Gloss) dries to a highly reflective finish. Polymer Varnish (Satin) offers moderate reflection, similar to most matte varnishes. The Matte is exceptionally flat. The different finishes can be intermixed, or used sequentially, to achieve the desired sheen. Note: Polymer Varnish (Satin) and (Matte) will lighten dark value colors, which is typical of non-gloss varnishes.
TEST FOR YOUR APPLICATION
Prior to actual use, it is very important to experiment with Golden varnishes on test pieces to become aware of how they perform and how they alter the surface appearance of 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 all variables are accounted for, and a successful varnish application will be achieved.
ISOLATION COAT
Only intended for acrylic paintings, do not use on oil paintings.
For future conservation and varnish removal purposes we recommend the use of an isolation coat prior to varnishing. An isolation coat is a permanent, non-removable coating that serves to physically separate the paint surface from the removable varnish. This will help protect the surface if the varnish is ever removed and make future cleaning and conservation easier to avoid working directly on top of the pigmented part of the work. Therefore, even if painted with delicate washes or large areas of colors that could potentially bleed, a clear barrier would safely cover the painted surface. It will also seal absorbent areas, which will result in a more even application of the varnish. In the event that no varnish gets applied, the isolation coat serves to decrease the water sensitivity of the paint surface, affording protection during routine cleaning/dusting.
Given the current state of conservation science, we feel the use of an isolation coat provides the most protection. However, isolation coats are also significant and permanent additions to a painting and inevitably will cause changes in the painting"s surface qualities. Whether these changes are acceptable is an aesthetic decision that each artist needs to make after sufficient testing. In addition, since it is non-removable, any mistakes or problems during this procedure cannot be easily corrected and there is always an element of risk that needs to be considered. We strongly encourage the artist to practice these procedures thoroughly so they feel confident and become familiar with any unforeseen problems. If you have any questions or concerns regarding the proper use or application of an isolation coat, please call Golden"s Technical Support Department at (800) 959-6543.
For brush application, the appropriate isolating medium can be made by diluting Golden Soft Gel Gloss with water (2 parts by volume Soft Gel Gloss to 1 part water). If a spray application is desired, a 2:1 mixture of Golden GAC-500 to Trasnparent Airbrush Extender can be applied with an airbrush, touch-up spray unit or commercial spray equipment. The absorbency of the surface will dictate the number of isolation layers required. For relatively non-absorbent surfaces, as is the case with a uniform paint layer, one coat brush applied or two coats spray applied are recommended. For more absorbent surfaces, which tend to be very matte, it is recommended to apply sufficient isolation coats to achieve a satin sheen on the surface. This may require two or more brush applied coats or three or more spray applications.
The isolating layer is of critical importance when applying a matte varnish over an absorbent surface to prevent a cloudy or "frosted" appearance from occurring. This frosted appearance results from the varnish and solvent being absorbed into the support, while the matting agent remains exposed on the surface. While we have carefully selected the matting agent that is in Golden varnishes to be as transparent as possible, it is still a dry particulate material. When the matting agent is deposited onto the surface, and is not a part of a continuous varnish layer, it appears as a white solid. If varnishing water-soluble paints, including watercolor, gouache and tempera, the isolation coat must be sprayed on in very light layers to avoid solubilizing the paints, which could cause loss of distinctness of the underlying image.
PRODUCT APPLICATION
POLYMER VARNISHES MUST BE THINNED WITH WATER BEFORE USE. Start with 4 parts varnish to 1 part water for brush, 2 to 1 for spray. Adjust as needed. The varnishes are supplied thicker than meant for application in order to keep the matting solids in the Satin and Matte finishes from settling to the bottom. Thinning the varnishes beforehand will also minimize the risk of foam by allowing any bubbles to release before drying.
Please see the following video for more information: Thinning Polymer Varnish
It is preferable to brush or spray apply Golden varnishes. Other methods, such as sponging or rolling, are not recommended, as they may result in problems such as: foaming, loss of film clarity, non-uniform coverage, excessive film build, sagging, or deposition of materials from the application tool.
Brush Application
Use a high quality bristle brush, such as those made by Purdy or Wooster, or for more control and smoother application, a wide thin flat color-wash brush. The Da Vinci Cosmotop Spin brushes are an example of this type.The size of the piece to be varnished will determine the size of the varnish brush. Work from ashallow container to help control brush loading. The varnish solution should wet only the lower 25-30% of the length of the bristles. It is always best to apply the varnish on a horizontal surface in order to minimize running or sagging. If vertical application cannot be avoided, as with a mural, it is extremely important that the varnish be thinly applied. In either case, it is better to apply two or three thin coats with sufficient drying time in between, rather than one thick coat of varnish. The latter will take longer to cure, staying soft for some time, and could result in drips or a cloudy film. Apply the varnish in a manner that allows it to be brushed out to the most uniform, thinnest film possible. Mentally divide the work into regions to be covered by each loading of the brush. These may be based on a systematic grid-like sequence or may follow natural boundaries of the piece. Maintain an even application by working from the center of each region outward. Lightly overlap into still wet, adjacent sections. When applying a satin or matte varnish, never apply more than two coats. If multiple coats are desired, start with the gloss varnish to build up and establish the multiple layers, then finish with one or two coats of the satin or matte finish. A thick film of these reduced sheen varnishes will result in film cloudiness, and loss of clarity.
Spray Application
The best way to achieve an even coating of varnish is to spray apply. This is particularly true for impasto surfaces. Spray application is required for any surface where the paint film is fragile, such as gouache, and should not be touched by application tools. 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. These varnishes can be sprayed from an airbrush, airless or air pressured spray equipment, or refillable aerosol equipment. In preparation 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 three to four light even coats instead of one or two thicker applications, allowing enough time for drying between coats (1-4 hours, until surface is tack free). Release the spray trigger if the motion of the airbrush is stopped during application in order to avoid an uneven build of varnish in one spot. Maintain uniform distance from the surface, and avoid the tendency to use 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 piece has been covered. To aid in achieving a more even application, turn the painting 90 degrees in order to apply the subsequent coat perpendicular to the previous one. A typical spray application lays down a film only 1/6 to 1/4 the thickness of a brush coat application. If maximum protection is required of the varnish layer, apply multiple coats. This is especially important when protecting colorants that are not inherently lightfast, as the thicker the total varnish film, the greater the protection from ultraviolet radiation. Because it is not recommended to apply several coats of a satin or matte finish, underlying layers should be established using a gloss varnish.
Cleanup
Clean all equipment immediately following application. If tools are wet, Golden Polymer Varnish can be removed with water. Ammoniated glass cleaner or a 1:1 solution of household ammonia to water may be use if the varnish has set.
Drying Time
The isolation coat should cure for 1 day before varnishing. When building up multiple coats, allow for 3 - 6 hours in between coats. Gently inspect the surface for tack, which may signify that the coat is not sufficiently dry. Let varnish cure several days before packing or transporting art. During transportation and storage, avoid contact of the surface with packing materials, including glassine, bubble wrap or any other plastic. NEVER STACK PAINTINGS, whether varnished or not.
Care and Storage
As Golden 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.
Only mix as much varnish as is required for a project and use within a week. Storing diluted varnishes for longer periods is not recommended, as this can lead to microbial growth, separation and/or settling of matting solids.
VARNISH TROUBLE-SHOOTING
If milkiness or opacity occurs in varnish layer, then
- if using a satin or matte varnish, and this only occurs over dark colors, this may simply be the nature of such a reduced sheen varnish (caused by the presence of the matting agent). There is no way of applying a satin/matte finish to a dark color without lightening it (the more matte the finish, the more potential for lightening dark areas). To restore the depth of the dark colors, apply a higher gloss to restore some of the sheen.
- if this is uniform across much of area, regardless of the darkness of the underlying colors, it may be caused by moisture entrapment. High humidity or a damp surface under the varnish layer often causes loss of clarity. Using a warm, forced air source to blow across the surface should help the moisture evaporate, restoring clarity.
- if varnish is not properly thinned, or is shaken or stirred excessively, air bubbles may become trapped within the dry film, causing a loss of clarity. The varnish must be removed.
- if a "frosted" area appears, a satin or matte varnish may have been applied over an absorbent surface (this is common for spray applications). The varnish must be removed, the surface sealed to reduce absorbency (apply gloss varnish), followed by application of a reduced sheen varnish.
If reflectance is not uniform, then
- if surface has varying absorbency, this may result in uneven gloss. Ideally, such a surface would first have isolation coat applied to provide a more uniform surface. However if varnish has already been applied, the surface must be sealed by applying 1 or more additional coats of gloss varnish, followed by the desired sheen varnish.
- improper mix of varnish. The varnish/solvent mixture was not thoroughly mixed. If different sheens were blended together (gloss with matte), they may not have been thoroughly mixed. If the diluted varnish is used over a long period of time without restirring, it may be separating (matting agents settling). To achieve a uniform finish, start with a fresh mixture of varnish/solvent (thoroughly stirred) and apply another coat (may also consider removing the existing varnish layers).
If brush strokes remain, then
- the varnish may not have been thinned sufficiently to level during application.
- the solvent was not compatible with the varnish.
- if the surface was absorbent, it may have caused the varnish to dry too quickly, and not allow it to level.
When spraying, if the surface is very pebbly or textured, then
- the varnish may have dried before reaching the surface. This could be caused by insufficient thinning (add more solvent), an extremely dry environment (add humidity, reduce heat, limit air flow) or by excessive air flow (reduce air pressure).
If the varnish is sinking in and not developing sufficient gloss, then
- the surface is too absorbent. Apply additional coats of isolating layers (only if no varnish is yet applied) or gloss varnish. Excessive dilution of varnish may also result in this problem.
If the varnished surface is too glossy, then
- apply a satin or matte finish of the same kind of varnish already applied.
If the varnished surface is too matte, then
- apply a gloss or satin finish of the same kind of varnish already applied.