Whenever I am done with a painting, I always do one last step, and that is to varnish the painting. It doesn't seem like an important step, but is crucial to the long-term life of the painting. Most people think of varnish as just a simple protective finish, and it is known for preventing a painting from fading. It does prevent art form losing it's color, but it also does much more than just that.
Varnish is simply a protective clear liquid that goes over the surface of a painting. Depending on the brand of varnish, it could have different types of luster, long term effects, and color. For example, some types of varnishes are crystal clear, while some appear slightly yellow in color after drying. I would avoid these. Some also dry to a matte finish, while others dry to a glossy and lustrous finish. I prefer to use Krylon's clear acrylic coating as shown below.
It does numerous things to the piece. First of all, it frankly makes the surface resistant to the elements. For example, even though this would probably never happen, in case something spills on the painting, it can be wiped off without damage. Not only does it provide confidence in the longevity of the piece, but you can be sure that no water or liquids will ever damage the painting.
If the painting is in a bathroom, varnish also helps because moisture doesn't affect the paint. This gives you added flexibility of where you can hang the painting. You can also display the painting in light without worrying about damage. Over longer periods of time, light fades the color, but the coating prevents this. Besides, having a well lit painting is always nice because naturally brighter up the colors. Also, art can collect dust over time even though it might seem unnoticeable at first. With a varnish painting though, you can easily wipe the surface with something like a slightly damp cloth.
So how do you varnish something? As you can see above, I like to use spray varnish. I don't like brushing it on, because it doesn't come out as smooth and even as using a spray. Also, you don't need any special brushes and can avoid the hassle of cleaning the brushes with solvents when you are done.
First of all, you want to make sure you are in a well ventilated area. You should also use a mask for safety. I don't use gloves, but you could just to avoid the solvents touching your hands. Take the painting somewhere outside and take note of the wind direction. You don't want to angle it where the wind is blowing the varnish back at you instead of at the painting.
Do not place the painting flat on the ground. Instead, place it laying on something at an angle. This will give you better and more even coverage. See the following examples below.
Next shake the can and start in a horizontal spray pattern going up the painting slowly. Move your hand in a swift motion spraying about a foot from the painting at first. This distance ensures evenness.
Next I go in a loose diagonal pattern . This adds another coat and also covers up any unevenness that might have occurred during the first coat.
You can check for unevenness by tilting the painting towards the light, as shown below. Here I intently made it uneven so you can see what not to do. In this example, there is more glossiness and evidently thicker varnish in the center of the painting. Also, as a word of caution, if your varnish takes more than a day to dry completely, do not spray all the coats at once. You one coat each day. For me, my varnish only takes a few minutes to dry over the surface, so I spray it all in one sitting.
The last step I do is to spray the sides of the painting. Usually when you go side to side horizontally or diagonally, you get less coverage towards the edges of the painting, so this last step helps.
And that's about it!. Though the painting dries quickly, it still retains a strong chemical odor. So, I leave it outside or in a garage with proper ventilation. You should really be cautious and follow what I do because varnish fumes are extremely flammable! They are also unhealthy to breath in. I let in sit for a few hours and then the odor dies down. After that, you should be all good! Down below is the end result. Again, I tilted it toward the light so you can tell it's been varnished. This is still a bit wet, but it is a nice smooth and even coat! I'll call this job complete!
