Acrylic painting - varnish question

I add a little gloss medium to my acrylics sometimes as I paint, with minimal amount of water to aid in blending,  and it can  give a pleasant shine.  Paint mainly on board, which does require a frame, but I don't think a mount is always necessary. I paint only for enjoyment now and for the therapeutic benefits it brings, so can really please myself.  I could be mistaken but I don't like varnish because I think it gives a 'plastic' appearance to the work?

Depends on the varnish - you can find matte ones, satin ones, high gloss ones, medium gloss - all sorts.  If you're going to use a matte, it seems to be a good idea to apply a gloss first, then lay the matte over that: can't say I've ever done that, but that's the advice I've received from one supplier at least.   As for varnishing generally - I don't think most acrylics are likely to come to much harm for not being varnished; I usually do, all the same.... it does keep them clean.  I have a couple of ca. 50 year old acrylics I never varnished, and while one needed a bit of a spruce-up (with a touch of mild soap and cold water) they don't seem to have suffered much.  

I’m always in the minority on the subject of varnishing acrylics. Frankly I can’t see any point in it, after all, it’s a type of plastic and will wipe clean quite easily. Varnish will undoubtedly, irrespective of what the manufacturers claim, get discoloured and may even start flaking, why risk that!  It’s not an easy task to remove varnish from any painting, oil or acrylic, I’ve had experience of it - nightmare in fact!

It's not easy to remove varnish, no!  I think I should prefer the term 'resin' to 'a form of plastic' - don't think me picky.....   The point of varnishing acrylics - and I'm not fanatical about it - is a) acrylic paint is actually softer than oil, and will absorb dirt; although - I still say you can clean it yourself, with that water and soap or even - pause for disgusted whimperings - spit.  And  b) that it does tend to zhoosh up the colours - as acrylic dries, the water, which contributes much to the glistening freshness of the paint, does, of course, evaporate.   And so the paint will go matte, depending on the brand - some heavier bodied acrylics will dry to a degree of sheen, the lighter bodied ones are more likely to become somewhat duller.  You can counteract this by using a gloss medium while painting, rather than just water.  But if you don't like using gloss medium - and I don't, much - a coat of varnish can be the only way to restore dull patches.  It doesn't have to be sprayed, or brushed on thickly - just a single coat should revive the colours, if they need it. I've found that every single brand of acrylic is different in these respects - some need a bit of after-care, and some really don't.  A brand I could just leave alone after applying it is Daler-Rowney's Cryla; and another is Winsor & Newton professional grade acrylic (the top version available, I forget the name they're using for it now).  Some other brands need either gloss medium, or varnish - or the picture can just die on you.   But - it's all a matter of taste and individual preference - Alan Bickley hates glossy paintings; I quite like them (much as Sylvia Evans hates ornate gold frames, and I love 'em).   It probably depends a lot on how you envisage the finished product - whether protected by a gloss or matte varnish, or left to speak for itself, as it were: I suspect it's a decision we make long before we've finished the painting. 

Yes of course it’s a resin binder, not sure why I used the word plastic Robert. I do enjoy painting with acrylics on occasion, they certainly have their place, plein air for one, as you can carry your work home dry! BUT, I’m totally hooked on oils for many reasons, I’ve given most of these reasons in my numerous  e-newsletter demos over the last five years. Varnish is a personal choice of course, matte is the only one that I ever use, and only if I consider that adding it will be beneficial, never as a matter of course!

Deciding whether to varnish or not , I look at the the way that the brush stokes add or take away from the painting.  Sometimes the surface varies a lot over the painting, so if it needs it I go for a satin finish.  Satin gives depth to the darks, but does not list way gloss reflects.