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GAC Products on Inkjet Prints

By Mike Townsend

The volume of e-mails and calls to our Technical Support Department reveals a consistent increase in the number of artists incorporating inkjet printing into their artwork. While some artists’ focus is making quality prints, others see the print as a starting point for creating original artwork. This article focuses on materials and application methods, and product interaction when working with GOLDEN products on digital prints.

Print Systems
Today the artist is presented with a wide assortment of precoated papers, canvases, specialty printers, inks, protective coatings and varnishes. In an effort to improve the performance of a print, as well as to control sales, companies develop printers, inks and substrates together as a system. If an alternative substrate is used, for example, the receptive coating may not allow the inks to penetrate as well as the recommended substrate’s surface, and so the print’s quality is compromised. Starting with an established system provides a baseline for the artist for future testing.

The key requirement for any substrate being considered for inkjet printing is how receptive it is to the ink system. Physical characteristics of the substrate impact subsequent product applications.

Below is a breakdown of benefits and potential issues of common substrates: Inkjet Papers – A range of papers are available, from very glossy photo stock to heavy matte papers. This group can include watercolor papers specifically produced for inkjet printing. Various paper stocks and coatings can experience color change and yellowing regardless of how the inks fare. Therefore, not all inkjet papers are suitable for archival use.

Inkjet Canvases – The canvases intended for use through printers tends to be easy to coat and seal because the surface is not very absorbent. If properly coated, the canvas texture can be retained and it can be stretched and framed like a painting. These precoats may not be receptive to all inks, and may also repel applications of mediums or varnishes. As with papers, inkjet canvas coatings may have inherent archival issues.

Uncoated Substrates – Artists have experimented with many materials for use in digital printing, including 100% cotton rag paper. Although some may be quite permanent and appropriate for fine art work, because they are not specifically developed for inkjet printing, these surfaces may cause poor reception of the inks. Without an appropriate sizing such as inkAIDTM or other ink receptive coatings the quality of the resulting print may be compromised. If used without any receptive ground coat, the high degree of absorbency means multiple applications of a sealer may be required to close the porous surface.

The two types of inks available for inkjet printing are dye-based inks and pigmented inks. Dyes are colorants, which are soluble in the solution carrying them. By nature they are more prone to fading from exposure to light, especially in the ultraviolet portion of the spectrum. Pigments are larger insoluble particles with significantly stronger bond strength holding them together and therefore, less subject to break down from ultraviolet light exposure.

Three ways to seal a print include spraying with GOLDEN Archival Varnish, brushing with GOLDEN MSA Varnish or applying MSA Gel with a squeegee. These Mineral Spirit Acrylic-based products should not distort water sensitive prints.

Pigmented systems are more permanent, but the dye-based inksets have a wider color gamut. Of course this is a generalization, but each artist will need to make a decision as to which one to settle upon. Their choice affects what substrates and subsequent coatings can be used as well. Dye-based inks are generally more water sensitive than pigmented inks, but this can be countered by using substrates designed to minimize the issue. Pigmented systems tend to be less vibrant than dyes and their water resistance reduces inadvertent reactions with a larger variety of coatings. The use of pigmented inks can allow for direct waterborne coating applications.

Sealing Coats
The function of a sealing coat is to reduce the absorbency of the substrate and also to encapsulate the inks, making them less susceptible to reacting with subsequently applied materials. It also seals the substrate’s ink-receptive coating if one is present. Each substrate will have a unique degree of absorbency and reaction to the initial sealing coats applied to it. Sealing allows for uniform varnish coats and the ability to apply and manipulate subsequent products more readily. Once a uniform layer has been established, the artist is free to “re-mark” — the post manipulation of a print with color and texture — with paints, gel mediums, or varnishes.

In many cases it can be difficult to apply water-based coatings directly onto the print without some color bleed — even systems deemed “water resistant.” Spraying provides the most even application of these coatings. Light, fast-drying seal coats can minimize the occurrence of inks bleeding or distortion of the image.

Once it is established that a waterborne coating can be used, then determine what properties are desired with this coating and what application method works best. For example, GAC 500 blended with Airbrush Transparent Extender makes a good overall spray coating, while Soft Gel (Gloss) thinned with water is better for brushing. Thin coats are best to seal the surface. Absorbent papers may require several coats to properly seal the paper. Gloss products provide better clarity and depth of color than semi-gloss or matte products.

If the image is too easily blurred with a direct application of a water-based coating, the most practical solution is to apply the GOLDEN MSA Varnish (Gloss) or Aerosol Archival Varnish (Gloss) as the primary sealing coat. This solvent-based acrylic varnish should not react with water-soluble inks or ink-receptive coats.

Assuming the print has been sealed with a compatible coat; manipulation of the surface can begin. The initial seal coat aids in stabilizing the inks and substrate, which in turn allows for more working time, smoother applications with less foam generation, and the ability to also work over the print, applying thin or thick layers of paints, gels and mediums. Commonly used GOLDEN products for “re-marking” inkjet prints include:

Gels and Mediums – Care must be taken to avoid excessive foam bubbles, distort water-sensitive inks, or otherwise harm the print. While some artists prefer to use semi-gloss or matte products, to ensure transparency and image clarity, the standard recommendation is to use gloss gels for texturing. Modify the gloss sheen later by finishing the work with a lower sheen topcoat, such as MSA Varnish (Satin).

Custom MSA Gel – This mineral spirit acrylic-based product allows for one-coat applications to combine reduction of water sensitivity, adding texture, and UV protection all in one product instead of having to apply multiple materials. However, if the MSA Gel is not going to be used over the entire print, an overall pre-coating of MSA Varnish (Gloss) creates a uniform surface for the gel. MSA Gel is available with and without the UltraViolet Light Stabilizer (UVLS) system.

Blended Paints and Mediums – GOLDEN Acrylics such as Heavy Body and Fluid are appropriate for “re-marking” sealed prints. Artist paints offer a significant advantage of lightfast pigments and range of color. The use of specialty colors such as Iridescent and Interference colors can add elements to a print that cannot be digitally created. Paints can be combined with gels and mediums to create translucent glazes. Refer to an article in issue 12 of Just Paint, titled “Defining Luminous Effects” for a better understanding of glazing.

Top left: Seal paper and canvas surfaces with
Soft Gel; allow to dry.
Top right: Apply thin coat Soft Gel as glue layer.
Bottom left: While gel is wet, lay print evenly
onto canvas.
Bottom right: Carefully place weight on print
to prevent buckling; allow to dry.

GOLDEN Varnishes
Varnishing provides significant protection by reducing change, such as fading and yellowing. The number of coats needed for such protection can vary based upon the application method and materials. Refer to the test results in this Just Paint issue and other GOLDEN information sheets for further information.

Both the GOLDEN MSA Varnish and Polymer Varnish contain UltraViolet Light Stabilizers (UVLS) to minimize fading, and some artists will prefer to use one system for both sealing the substrate and also for the actual UV protection. Both products can be used on a sealed surface or directly onto a print, as long as there are no solvent or water sensitivity issues. These products will offer water resistance but not make a print waterproof. However, applying a varnish will allow for general cleaning and handling.

Mixed Media
Whenever mixed media is being considered for artwork, it is important to understand product relationships to assure adhesion and compatibility. For example, it may be necessary to seal between layers, especially if working with delicate media, such as pencil or charcoal. Testing various products over one another before committing them to the print can mean the difference between success and failure. When inkjet prints are involved in mixed media work the most important issues are adhesion and whether various materials will
distort the print.

Preparing Prints for Use in Collage
Rather than the artwork being limited to the printable substrate, some artists want to add printed elements into a painting. For collage work, once the sensitivity of the print has been addressed, the print can be used as would any other paper element in the composition.

Mounting Prints to Canvas or Panel
Acrylic mediums and gels can be used as glues for mounting prints, but if the print is one with water-sensitive materials, this should be addressed first. A good example of this is attaching a giclee print with water-sensitive dye-based inks on watercolor paper onto a panel.

Prepare the back of the paper with one or two thin coats of Soft Gel. This seals the absorbency prior to actually attaching the paper to the panel. The panel’s surface should simultaneously be prepared with a coat of Soft Gel to seal the panel’s absorbency. By pre-coating these surfaces, less Soft Gel is needed for the actual gluing process and in turn, a better bond is created. This process also reduces the chance of edges curling and air pockets developing due to lack of gel between the two materials. Mounting large prints can be the most difficult as the gel needs to stay wet until the two objects are ready to be glued together.

The Importance of Testing
The digital print world moves at a very fast pace. By the time this issue of Just Paint is published there could easily be several new substrates and colorant systems in the marketplace. It is imperative to test and re-test materials for compatibility. Inkjet canvases and papers have special receptive coatings, and these films may cause adhesion failure of certain materials. Some ink may be touted as water resistant, but when a heavy coating of acrylic gel is applied, the moisture remains on the surface long enough to cause the image to blur or color to change. Therefore, do not assume because a product worked fine for one kind of ink and a particular canvas it will perform as well on others.

If the intent of the artist is to create a lasting artwork, they need to be prepared to spend time gathering information and conducting some tests. This new digital medium can provide so many options for the artist. It can serve as simply a print media or become part of a much more complex mixed media work. So many questions remain unanswered as to the ultimate permanency of this media. As more artists push the boundaries of this technology and as their customers demand greater confidence that their work will remain viable, the products will continue to improve. It is our goal to continue to investigate what is possible within this media and provide our best practice ideas as the field continues to evolve.

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