Acrylic varnishes offer a protective coating to a finished painting, keeping it safe from dust and surface damage (scratches etc). Some varnishes also have UV light resistors which will prevent colour fade. We recommend applying an isolation coat over your painting prior to varnishing - a soft gloss gel medium would be ideal for this. This will allow for the varnish to be removed in future, if necessary, with no damage risk to the painting itself. Always ensure that you varnish work in a dust and dirt free environment, and remove any dust or dirt from the surface of your work prior to varnishing.
Spray vs Paint
Acrylic Varnishes are available in an aerosol can as well as in a bottle. There’s a good argument on both sides regarding which is easier to apply. With sprays make sure you start spraying on something other than your finished artwork (the work surface beside perhaps) in order to gauge how much pressure you need to push the nozzle with to get the right amount of varnish coming out. Then continuously move the spray over the finished work making sure you give the whole surface as even a layer as possible. Always stop spraying if you stop moving, to avoid an uneven application. A few thin layers is always better than 1 thick layer as it will allow for the varnish to dry properly and be more solid and stable in the long run. Read the label of the varnish to find out the drying time you need to allow between layers. A good tip is to turn your work 90 degrees each time to apply and new layer of varnish as this will help to achieve a more even application. Sprays can be particularly useful when varnishing a delicate work where applying varnish with a brush could damage the surface. It is also good for impasto work where varnish might gather in between undulations in the surface if applied by brush.
Brushing varnish on can also be a little tricky. First give the varnish a very good stir (but not shake as you do not want air bubbles for form), check the consistency; if it is too thick then thin it down with a little water or an acrylic thinner. Use a relatively stiff haired varnish brush (usually hog hair with split ends) and work on a flat surface where possible. Only load the bottom third of the brush as if you load the brush with more varnish than this it will be very difficult to apply it evenly. As with spray varnish, more layers is preferable to one thick layer, so it is good to try and practice applying the varnish thin and evenly. When applying a varnish with added matting agents (satin, semi-gloss or matt varnish) it is a good idea to only use it on the final layer of varnish in order to maintain the appearance of the colour depth and brilliance in your work.
With any varnish application, it is much easier to clean up when the tools are still wet as you can do this with soap and water. Dried acrylic varnish requires washing with ammonia.
MSA (Mineral Spirit Acrylic) varnish is a more permanent layer than regular acrylic varnish and needs to be cleaned/thinned with solvents, although it is still acrylic based.