Varnishing Oil Paintings

If we look at oil painting today, many of the practises we accept without question are the result of the limited technology when the oil painting technique was developed. If we look at stretched canvas, still favoured by many artists, we see the only possible way a large flat surface could be produced a few hundred years ago. Small paintings were often painted on wooden panels. These were relatively easy to produce by a skilled carpenter by glueing smaller boards together. Above all they were lightweight. A large panel would be more like the wall of a building and have all the problems of a ‘portable’ wall. Large panels of anything (wallboard, chipboard, cardboard, aluminium, etc) is a recent invention. Large glass panels are even more recent, so framing a large painting under glass was not an option. The solution to protecting the surface of a large painting was varnishing. Like stretched canvas, its still favoured by many artists today.

A hanging painting, not under glass, will eventually need to be cleaned. Varnish will have to be removed and replaced with a clean coating of fresh varnish. The critical factor here is that the varnish has not impregnated the layer of paint which will then be removed with the old varnish. Alkyd resins, like Liquin, will bond to varnish so the art material suppliers recommend the ‘last layer’ of paint should be vegetable oil like Linseed. If you intend to varnish a painting, and you have used an alkyd resin as a medium, the final ‘oiling out’ should be with a vegetable oil. It will be necessary to wait several months for this oil to thoroughly harden.

Varnishes - Liquid Method and Aerosol

Using a cloth to apply the varnish is also recommended (check out the Windsor & Newton website). As most of my paintings are on ‘loose canvas’, I find using a wide brush more suitable to my needs. The problem here is cleaning the brush after varnishing. If every trace of varnish is not removed, the brush will harden and cannot be used again. It would take an enormous amount of good quality spirits to clean a brush of 2″ or 3″ width. I have solved this problem by suspending the brush by a wire contraption in an airtight glass jar (see photo), with a layer of spirits at the bottom of the jar. This stops the brush from drying out, so I never have to clean it and it is always ready to varnish.

Apply the varnish gently with horizontal then vertical overlapping strokes. Gently to avoid bubbles in the varnish and also disturbing the paint layer. Dust is a problem both applying the varnish and waiting for the varnish to dry (lie the painting flat) so vacuum the area before you start. Don’t use a sweeping brush as this will only make the dust airborne to later settle on the painting surface.

The range of varnishes available is easy to check out, online or in an art suppliers shop. Windsor & Newton have a gloss and matt varnish which can also be mixed to produce an in-between finish (like satin) to suit your personal preference.

If you very few paintings to varnish, or you only varnish occasionally, you can use the aerosol varnish. This is fast and easy to apply but costly.

All this bother with varnish is necessary if the painting is not framed under glass. I frame most of my paintings under glass, after ‘oiling out’ with Liquin. This is more to do with the time involved with varnishing than anything else. At some time in the future the painting could be ‘oiled out’ and varnished because, hopefully, by then the painting would be thoroughly dry and clean.

9 thoughts on “Varnishing Oil Paintings

  1. Pingback: Absolute beginners – Varnishing Oil Paintings « PictureS

    • Yeah, that’s some piece of engineering :) Damar Varnish, difficult to apply and difficult to remove. Furthermore, the painting would have to be thoroughly dry (6 months to a year – aaagh!). I recently felt obliged to clean a painting I had sold about 30 years ago. The person had it hanging over the fireplace. It looked like an ‘old master’. Not in a good way but in a tobacco coloured way. I had varnished it with Windsor & Newton’s Satin (removable) varnish. It went fine, slow, but OK. A little wash with soapy water (damp cotton-wool) and White Spirits removed the varnish. Luckily the painting was clean when I started to remove the varnish as I noticed some colour lifting. This was because the painting was not completely dry when the varnish was applied. I left it as it was and applied an aerosol varnish (satin) and reframed under glass. If this had been Damar I’d be in a ‘real pickle’. I have an old book somewhere which suggested applying a layer of wax dissolved in spirits and brushed to a satin finish. I would always go for a less permanent solution.

      • Thanks for the reply I keep taking out the Damar and then back off applying it – I think I’ll leave it in the ‘might use it at some stage’ section of my art stores. I made a variation of your varnish brush holder – I cut a hole in the lid of a jar and stuck the handle up through it then I used a hot glue gun to hold it in place and seal the gap. Now I have a full length brush handle to work with and can pop it in the jar when I’m finished. The ironic thing is that after building my contraption I decided against the damar varnish and used an aerosol ….so my varnish gismo is untested!

      • Check out my piece on ‘oiling out’ (Absolute Beginners – part 3) before varnishing. Windsor & Newton have 2 varnishes, gloss and matt, which can be mixed to produce a range of ‘satin’ finishes to suit your paintings. Aerosol is great for ‘one off’ jobs, but too expensive for large numbers of paintings.

      • I had actually looked at your varnishing blog (you’re a great source of tips and tricks!) and the W&N ‘satin’ mix is what I would traditionally use. I have a tin of Spectrum Crystal Damar Varnish and I’ve been nervous about using it – hence the initial enquiry. I agree about the aerosol, I rarely use it (not environmentally friendly ether) however it was only a small canvas and I’d run out of W&N.

  2. Pingback: Woodland Lake – Time Lapse Painting « PictureS

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