PATIENCE! The key word to varnishing a painting. The paint film requires time to add bits of oxygen to the painting. There is nothing to accelerate the oxidation process. A painting can feel dry to the touch and a product like Liquin can accelerate the drying process (to the touch), not the oxidation of the paint. That requires time and patience. Stopping that process can compromise the long-term stability of the painting.
I varnish my painting because I like the look and it makes a painting easier to clean. The colors become richer, the darks "sink" into the canvas as they dry. Varnishing will make your darks appear as they did when you first applied the paint, creating an even surface to the painting.. But varnishing isn't necessary and is an aesthetic decision of the artist.
Gamvar by Gamblin
Robert Gamblin of Gamblin Colors recommends varnishing paintings unless artists dislike the look. Waiting 3 - 6 months to varnish is best, but artists using Gamvar can safely varnish sooner because Gamvar's mild solvent will not dissolve the glaze layers of paintings. Today's paintings dry quicker including Gamblin Artists' Grade Oil Colors which dry more quickly than oil paints of past centuries. (The linseed oil today is more refined with less contaminants to slow the drying process.) Gamvar is better than dammar varnish because it does not yellow and remains easy to remove with mild solvents such as Gamsol OMS. Click for more information on Gamblin Varnishes
Winsor & Newton Varnish
When varnishing an oil painting, it is essential that the painting is dry for at least 6 months according to Winsor & Newton. How can you tell if the oil painting is completely dry? According to Winsor & Newton, dip a lint-free rag in solvent such as W & N Artists' White Spirit, gently rub on the paint. If color shows on the rag, the painting is not dry and shouldn't be varnished. So, what should you do if you want your painting varnished before it sits around in your studio for 6 months to a year drying? I use a temporary/retouch varnish. Before using a retouch varnish or final varnish
- Varnish in a dust free environment
- Clean all dust or brush hairs off the painting to be varnished
- Varnish one entire coat in one sitting. Do not stop part way through.
- Use even, thin strokes over the entire painting.
- Make sure to have good ventilation while you varnish.
- Your varnished painting will be dry in a day or two.
- Retouch varnish can be applied almost immediately when the painting feels dry to the touch.
- A thin layer of retouch varnish allows the paint to continue drying.
- It can be easily removed before the final varnish.
- Retouch varnish can be easily sprayed on for an even coat.
- It can also be brushed on. But if the paint is still slightly wet in a few places, it will smear.
- I can send my paintings to a gallery or collector before the final varnish with a retouch varnish on them.
- Retouch varnish doesn't have a nice a look as varnish. Sometimes, I've seen it "sink in" in places on the painting.
- Inform your gallery or collector about the varnishing, if it needs to have the final varnish or if it is retouch varnish.
- If I sell to someone in town and I haven't applied the final varnish, I offer to make an appointment with them the following year to apply the final varnish. They can also take the painting to a curator or give them directions and products to do the job themselves. It depends on what you and they feel comfortable with.
- The final varnish looks the nicest, but you need patience to wait for the paint to dry.
- The retouch varnish doesn't need to be removed before adding the final varnish.
- There should be two coats of varnish applied to a painting.
- Wait overnight before applying the second coat.
- Like house paint, the varnish should be applied in thin layers.
- There are many varnish finishes from matte to high gloss and in between. Some varnishes will yellow or crack with age, others are clear. So, research varnishes before trying one.
- Try the varnish on an old painting to see if you like the finish.
- Use even strokes in one direction for each layer
- Use a soft brush that won't leave brush marks.