Varnishing 101

We get more questions about varnishing than with any other stage of the painting process.

Varnishing should be an almost mechanical process undertaken to give your painting a protective coating with the surface quality you prefer (gloss, satin, etc.) and possibly an enhancement of colour contrast. But, if you leave it till the last moment and use a varnish you are not used to, you can ruin the work you are trying to protect.

Anxiety and disappointment can be avoided if you do sample pieces using the same materials as the painting and varnish them, not the painting, until you get the effect you wanted. Ideally, temperatures should be 18 C – 24 C, with relative humidity between 50% and 75%.

Water-based varnishes are tricky to apply and not removable if you dislike the effect, so we suggest they should only be used by artists who have already tried the above experiment.

NOTE: If you wish to preserve the unique, velvety, matte surface quality of Atelier Free Flow, do not varnish Atelier Free Flow paintings. Instead, protect them under glass instead.

Chroma Solvent Finishing Varnishes

We recommend and prefer our Chroma Solvent Finishing Varnishes, because they can be used on all our Chroma paint brands, such as Atelier Interactive Acrylic, Atelier A2 Lightfast Acrylic, Jo Sonja Matte Flow Acrylic and Archival Oils.

Application is by brush (a broad house paint brush), and clean up is with mineral spirits. If applying multiple coats, allow 24 hours drying time between applications. Choose from these finishes:

Gloss Solvent Finishing Varnish

Apply as is for a full gloss, usually one coat. To reduce gloss add Invisible Varnish to your taste. Try 2 parts varnish to 1 part Invisible Solvent Finishing Varnish, up to 1:1 for less sheen.

NOTE: These varnishes have an anti-mould additive which is diluted if you add turpentine, so to maintain the mould protection for tropical conditions dilute with Invisible Solvent Finishing Varnish instead.

Satin Solvent Finishing Varnish

This is our most popular, most unobtrusive varnish.

• The satin finish contains a matting agent and the container needs to be gently shaken before use to make sure it is evenly suspended. For full bottles: remove some varnish so you can shake the contents easily, then return to the full bottle before using.
• Satin varnishes should not be diluted with turpentine because the ratio of matting agent within the varnish is critical to maintain a true satin finish. Adding turpentine will increase the sheen, however for a satin/gloss finish we recommend diluting Gloss Solvent Finishing Varnish as described above.

Invisible Solvent Finishing Varnish

This varnish offers mould protection without altering the look of the painting.

• Use only one application of this varnish.
• It can also be used on oil paintings as a “retouch” varnish, while waiting out the advisable 3-6 month period for an oil painting to cure before applying a heavier protective varnish.
• On acrylics, it can be used for mould protection. It does not alter the appearance of matte surfaces and does not stain paper.
• If you can varnish uncured Atelier Interactive paintings with any Chroma Solvent Finishing Varnish.

Resolubility

This is an attractive feature of all these solvent varnishes, which can be cleaned at some later date by swabbing with mineral spirits.

Water-Based Acrylic Varnishes – Popular But Difficult To Use

We get more distressed phone calls about water-based varnishes which did not behave as expected, than on any other subject. Here’s what you need to know about the Atelier Varnishes.

• All water-based varnishes are non-removable. Solvents like acetone will remove them, but will also remove the painting.
• Water-based varnishes are much more difficult to apply evenly than the turpentine-based ones, and there is always some apprehension when varnishing. We recommend water-based varnishes should always be tried out first on a sample before used on a finished painting because once applied they can’t be removed.
• On acrylic paintings, apply an isolation coat of Atelier Fast Medium or Atelier Binder Medium to seal your painting prior to varnishing.
• Do not over brush when applying varnish as this can leave brush marks.
• Water-based varnishes can remain milky for a long time if some of the water gets trapped in the varnish layer. Placing near a heat source will usually fix this problem.
• Water should not be added to the Satin or Matte varnishes.
• Gently shake Matte and Gloss Varnishes before use to make sure the matting agent is evenly suspended.
• Use a large brush and set the painting on a gentle slope to catch any excess varnish which will run downwards because it is very liquid.
• Do not worry if the surface seems slightly tacky. It will firm up over a couple of weeks curing.
• If you are pressed for time or in doubtful weather, we recommend the Chroma Solvent Varnishes.

As with most water-based finishes, you can handle painted objects when they are dry to the touch, but maximum durability is not achieved until varnish reaches its cure time (at least 2 weeks under normal conditions).

Atelier Universal Medium/Varnish

Atelier Universal Medium/Varnish offers several advantages.

Use as a Medium

It is very liquid and can be added to the paint for fast-drying, thin layering techniques, but its main use is for varnishing.

Use as a Varnish

• This product, when used as a finishing varnish, is the only water-based varnish that we know of which is equal in its finish to a solvent-based varnish and is also very easy to apply. We recommend diluting the first coat about 1:1 with water, which allows the painting to absorb the extra liquid easily. When this has dried it enhances the colours without adding much gloss and is sometimes preferred to a satin varnish containing a flatting agent.
• If a more glossy finish is desired the next layer or layers can be applied quickly and easily because the liquid varnish spreads readily over the sealed surface and can even be over brushed without problems. Allow about 30 minutes between coats.

As with most water-based finishes, you can handle painted objects when they are dry to the touch, but maximum durability is not achieved until varnish reaches its cure time (at least 2 weeks under normal conditions).

Jo Sonja Water-Based Polyurethane Varnishes

Polyurethane provides the toughest finish available. The three types of Jo Sonja Polyurethane Water Based Finishes available are Gloss, Satin and Matte. All varnishes have excellent brushing qualities and may be used inside or out to provide durable, long term protection. These varnishes dry clear and are non-yellowing. They have excellent corrosion, chemical, scratch and wear resistance.

• Gently shake before use to ensure complete suspension of ingredients.
• Apply varnish using a large, soft bristled varnish brush with a gentle criss-cross motion. Apply thin coats, covering a small section at a time. Smooth out the strokes by brushing in the same direction as the wood grain. (Several thin coats are better than one thick coat.)
• Allow at least 1 hour between coats, as there will be less “drag” on the brush. Do not exceed 4 coats per day.

A slight milky appearance may occur when applying Jo Sonja’s Satin Varnish. This is normal and is more obvious on dark backgrounds. The milkiness should disappear as the varnish dries and cures. Sand lightly if 24 hours lapse between coats to ensure good adhesion. Apply at least 4 coats for maximum protection.

As with most water-based finishes, you can handle painted objects when they are dry to the touch, but maximum durability is not achieved until varnish reaches its cure time (at least 2 weeks under normal conditions).

Jo Sonja Decoupage Water-Based Polyurethane Varnish

Jo Sonja Decoupage Varnish is a heavy-bodied version of Gloss Varnish for artists who like to finish their projects with a thick, lacquer-like coating. It has been specially formulated for decoupage and collage artists to hide the edges of cut paper. Applying 8-10 coats of Decoupage Varnish is equivalent to 35-40 coats of thinner varnishes.

• A coat of Clear Glaze Medium is recommended as a barrier coat prior to varnishing.
• Gently shake the varnish and apply undiluted to the surface. If thinning is necessary for the first coats, add a few drops of Flow Medium, Retarder or distilled water to thin slightly. Do not over dilute.
• Apply Decoupage Varnish in criss-cross motion using a soft but firm brush suitable to surface size.
• Smooth by brushing final strokes in the direction of the wood grain. Avoid overlaps or drips along the edges .
• Allow to air dry a minimum of an hour before applying additional coats. Drying time depends on the number of coats applied. climate and humidity. A hair dryer may be used to speed surface drying. Avoid excessive heat which could cause crazing.
• A minimum of 8-10 coats will be required to hide the edges of paper.

As with most water-based finishes, you can handle painted objects when they are dry to the touch, but maximum durability is not achieved until varnish reaches its cure time (at least 2 weeks under normal conditions).