Varnishing Watercolour

CAUTION: The varnishing of watercolor paintings is a nonreversible addition to the artwork that will permanently change both the nature and appearance of the piece. Understanding these issues as well as performing application testing is critical before applying any varnish to a watercolor painting.

General Issues

Some artists feel restricted by the conventional practices designed to protect their artwork. The desire for the watercolorist to display their artwork without a glass barrier creates numerous considerations for the artist or collector because of the fugitive and delicate nature of watercolor paint films and the fragility and absorbency of paper. When a watercolor is taken out from behind glass it loses a physical barrier that prevents contact with dust, dirt, smoke, grease, humidity, ultra violet radiation and anything that can exert force upon it. While varnish can protect the piece from many of these conditions it can not shield the watercolor to the extent that a frame and glass can.

Permanent Addition

Because papers and other watercolor substrates are highly absorbent, any varnish applied to the surface will soak into it and become a permanent, nonremovable addition to the piece. Once varnished, the watercolor can
never be returned to its original condition.

The impregnation of the substrate with varnish could recategorize the watercolor as a mixed media piece and
potentially exclude it from being considered a watercolor by some societies, museums and conservators

Change in Appearance

The addition of varnish to a watercolor painting will:

  • Change the appearance, texture and feel of the paper substrate
  • Darken colors with the use of a gloss varnish
  • Lighten colors with the use of a matte or satin varnish

Since varnishes offer a sheen that is different than that of the original watercolor painting the artist may want to consider photographing the piece prior to applying varnish.


Varnish Application

A varnish functions as a tough yet flexible protective film over artwork. It is designed to reduce damage caused by humidity, dust, dirt, smoke, ultra violet radiation, scuffs and scratches. Varnish should ideally be a removable coating that should endure environmental abuses that would otherwise compromise the longevity of artwork. When applied on weakly bound media like watercolor paint films, varnish also has the ability to seal and hold the pigment and binder in place on the paper.

GOLDEN Archival and MSA Varnishes are both mineral spirit based acrylic varnishes that are formulated with UVLS (Ultra Violet Light Stabilizers) which work to reduce the effects of UV radiation. They create tough but flexible films that are suitable for interior as well as exterior applications. While Archival Varnish is available as an aerosol, MSA Varnish needs to be thinned for brush application or used with appropriate spray equipment. The Polymer Varnish is a water based system that also offers UVLS, although is less effective in providing UV protection. There is also a concern in using water based materials over water sensitive media since this can lead to bleeding or streaking, especially when brush applied.

All of these varnishes are available in Gloss, Satin and Matte.

When varnishing watercolor paintings, be aware that although an increased number of coats will result in greater protection against UV radiation, it also reduces the textural quality of the paper and paint.


Varnishing Options

There are three options for varnishing watercolors on paper or on GOLDEN's Absorbent Ground. With any of these options we strongly suggest first testing the application on a sacrificial piece of similar composition in order to rule out any unwanted results or potential problems that may occur. Performing a test prior to application will also increase one's skill and confidence when varnishing the chosen artwork.

1) Direct Application Using Archival Varnish

This option is the easiest and quickest in application but is nonremovable. We recommend, using the Archival Varnish whenever possible as it comes in an aerosol and allows the varnish to be applied without touching the fragile watercolor.

We recommend applying no more than 6 coats of the Archival Varnish and always beginning with Gloss in order to retain clarity and finishing the last coat or two with the sheen of your choice; Gloss, Satin or Matte. If you were to apply all the coats in Satin or Matte the result could be a cloudy or dusty look due to a concentration of matting solids.

2) Isolation Coat and Varnish with Spray Equipment

This option requires the use of spray equipment as well as an initial application of a non removable isolation coat. The isolation coat will seal absorbent areas and allow a more even varnish application, while also protecting the artwork if the varnish is ever removed. To avoid bleeding or streaking of the watercolors, always spray apply the isolation coat rather than use a brush. The recipe for a sprayable isolation coat is two parts GAC 500 to one part Airbrush Transparent Extender.

Once an isolation coat or two is applied and allowed to fully dry then any of our varnishes may be used. For spray applications, 4-6 coats are recommended, while for brushing we recommend 1-2 coats of the MSA Varnish or 2-3 coats of the Polymer Varnish for best performance.

3) Isolation Coat and Varnish Brush Applied

The third option takes advantage of both options 1 and 2 in order to incorporate removability of the varnish without the need for spray equipment beyond the aerosol can. If the watercolor is on paper spraying two even coats of the aerosol Archival Varnish (Gloss) is usually enough to seal and adhere the pigments to the paper. If the watercolor painting is on Absorbent Ground, then three even coats of Archival Varnish (Gloss) are generally required to prevent bleeding or streaking. After these have fully dried, brush apply an isolation coat composed of two parts Soft Gel (Gloss) to one part water. Be careful to mix the isolation coat slowly to avoid foam and bubbles. Once the isolation coat has dried, apply either the Archival (4-6 coats), MSA (1-2 coats) or Polymer Varnish (2-3 coats).

Additional Resources
Mark Golden's blog entry addressing varnishing watercolors
Just Paint article addressing testing and protective coatings

The above information is based on research and testing done by Golden Artist Colors, Inc., and is provided as a basis for understanding the potential uses of the products mentioned. Due to the numerous variables in methods, materials and conditions of producing art, Golden Artist Colors, Inc. cannot be sure the product will be right for you. Therefore, we urge product users to test each application to ensure all individual project requirements are met.