An uneven finish in your painting, some parts matte, other parts glossy can be very off-putting to the viewer.
A unified finish enhances the colours and is a great way to add both a professional finish to your paintings and add dollars to the sale price.
No one technique for varnishing suits every situation. The texture of the paint surface, the desired finish, speed of completion, etc all affect which technique is best to use.
On a side note, it’s also the number 1 trick to making your acrylic paintings look like oils.
What exactly is a Varnish?
A thin protective layer between the finished painting and the atmosphere. It should be transparent, colourless and form a good bond with the paint surface yet still be removable without affecting the painting. It is usually a combination of a resin and a solvent and applied to the painting when it it thoroughly dry – with acrylics this can be within 24 hrs.
Acrylics attract dirt
Acrylics are different than oils because they are more flexible when they dry leaving a softer exterior than oils.
This makes it easier for dirt and dust to adhere to, this soft skin can make removal of varnish tricky so some tutors advice placing your acrylics behind glass and not varnishing.
However, I have always varnished my paintings following a proper procedure as I prefer the aesthetic without glass.
With the right varnish and technique, it can not only benefit the longevity of the painting but enhance the finish – turning matte to gloss and bringing the colours to a new vibrancy.
When acrylic paint dries and the water evaporates off, small droplets of the polymer (the binder of acrylic paints is an acrylic polymer) join together to form one mass – this holds the key to the softness.
They also leave very tiny micro pores that are left open to the elements and these again collect dust.
If you cover the paint with a harder surface it will help to protect it from extremes in temperature or humidity, it also provides a layer than can be cleaned, rather than trying to remove dust particles ingrained in the paint layer.
If in future the varnish will need to be removed, taking away all the dust and dirt with it, and replaced with a fresh coat you need to be able to wipe the varnish back without disturbing the paint. For this you need an isolation coat.
An isolation coat is a transparent layer of medium that physically separates the underlying layer of paint from the varnish to be applied.
When a solvent is used to dissolve the varnish, the isolating layer will prevent it from reaching the paint layers, where damage could occur.
Golden Soft Gel (Gloss) thinned with water is a suitable isolation coat. It provides adequate leveling and foam release. See (How to apply an isolation coat to acrylics)
Pro tip: The isolating layer is also of critical importance when applying a matte varnish over an absorbent surface to prevent a cloudy or “frosted” appearance from occurring. This frosted appearance results from the varnish and solvent being absorbed into the support, while the matting agent remains exposed on the surface, where it appears as a white solid.
The cake mix is the paint, soft and moveable. The next marzipan layer is the isolation coat, slightly thicker but still flexible, the final icing layer is the varnish – harder, slightly more brittle but protects the cake inside.
I recommend a brush varnish for works that are quite smooth in finish and are non moveable. i.e acrylics, oils. However, if the surface is too impasto pools of varnish will settle in the nooks.
I’ll always assess the surface and texture to see what is more applicable, brush or spray. If you have delicate multimedia pieces or highly textural works spray varnish will be the way to go.
Pro tip: If you are using pastels or chalk it it advisable to fix them first with a pastel fixative.
1. Get a clean, wide brush – I usually use a 2 inch flat nylon brush, you can use a ‘varnish’ brush but it is not essential. I wouldn’t recommend a decorators brush as it will show too many brush marks, you want a brush that is smooth to the touch so you can just glide it over the surface.
2. Pour out some varnish into a shallow dish. It is easier to control the amount of varnish on your brush this way.
3. Lay your work on a board -I use a piece of mdf, or newspaper, you are bound to get some overspray and/or drips.
4. You need to work quick but gently – Apply in long even strokes to cover the surface top to bottom while moving from one side to the other.
5. Work side to side, left to right, slightly overlapping each stroke – you are aiming to have no visible brush-marks
6. Once you leave an area, do not go back over areas that you have done. If you do, you risk dragging partially dry resin into wet, which will dry cloudy over dark colors. If you missed any areas, allow to dry completely and re-varnish. 3 thin coats is better than 1 thick one.
7. After varnishing. I often cover my painting with a board slightly larger than the canvas, resting it on props so it hovers and reduces the amount of dust that could fall on the wet varnish layer. Alternatively with large canvass I will prop them facing a wall when the varnish is semi dry.
1. Change the surface finish to gloss
2. Making the surface more matte
3. Provide a more unified finish to the various areas of a painting
4. Increase color saturation
5. Protection for the paint surface
6. Allow for ease of cleaning
7. Protection from UV radiation
Have you ever noticed how much better paving look when it’s raining? The reflection of the water on the paving slabs makes them look fantastic, the same is true of colours in paintings.
When a permanent gloss sheen is on a pigment it looks richer and more saturated.
In an Oil painting initially it is the oil that gives the glossy effect, however, over time as the oil dries out it is actually the varnish that gives the sheen.
Different finishes of the same brand can usually be intermixed within each product type or used sequentially, to achieve any desired level of gloss.
Pro tip: A word of warning when using a matte varnish, if not correctly mixed the matting agent (which is white) can sometimes leave a milky finish to your paintings. This is particularly noticeable on blacks.
As varnish has a harder surface than the dried Acrylic paint it helps protect it.
When an isolation coat and varnish are applied correctly, the painting will be able to be cleaned easily. Used correctly the thinners used to remove the varnish will not penetrate the isolation coat and damage the paint film.
Ultra Violet Light Stabilizers, which can be found in some modern varnishes disperse UV radiation before they hit the surface of a painting. These varnishes are especially useful if you’re using materials that haven’t got a great lightfastness. It won’t render the surface completely lightfast but will considerable lessen the effects.