I’m starting a new monthly ‘ Ask Andrea ‘ series on my blog, and recently asked my mailing list to send me their acrylic questions. The most frequently asked questions I got (and usually get in my lectures) were about finishing acrylic paintings. So for the next several installments, I’m going to devote my answers to this topic. Here’s a sample of the questions- maybe you can relate to some or all of these!
" I would love to learn how to "finish" acrylic paintings. What should my last coat be? Should it be different for thick " bumpy" mixed media? Do I need to use a varnish when I have used several coats of glazing liquid and/or other mediums? If I do use a varnish, can I still paint on top if I want to modify the painting? What about "faux encaustic" paintings? " - Denise
" I have done canvases that had acrylic paint on them, as well as graphite and ink. I would really love to know the exact formula for coating the canvases so that they look shiny but the painting underneath still shows through. I have tar gel and glaze. Can I mix these together and apply them to the canvas? If so, what is the formula for that. What else can I use and will it smear the painting? I have not tried to coat any of my acrylic paintings yet as I am afraid to ruin them. " -Karen
" I have just done a mixed media piece and it is bumpier than normal - I have some Golden tar gel - can I just pour this on to even it out? " - Nola
FINISHES VS VARNISHES
To start to answer these questions, it's important to distinguish between a “ finish” and a varnish. I see these words used in different contexts by different people, but when I'm talking about finishes and varnishes, this is what I mean:
Finish- a permanent layer made with acrylic mediums or gels, used for aesthetic purposes
Varnish – a removable, solvent-based product used for protecting the painting (also for aesthetic uses)
Today I'm going to focus mostly on finishes, specifically the two mentioned above - using acrylic gels and mediums to mimic the look of resin and encaustic.
ACRYLIC LIKE RESIN
The best way to think about gels and mediums is that they are just paint without pigment – they are the binder that’s in acrylic paints, in different consistencies and sheens. There's a whole slew of them, and use you can use them in many different ways, but for a resin look we want those that self-level.
Self-Levelling Gel, Clear Tar Gel, and GAC 800 can all impart the smooth, high gloss look of a traditional two-part resin epoxy. Unlike many resins, however, they are archival (non-yellowing), and do not have the same toxicity issues that resin generally does.
Each of these three have slightly different qualities.
<----THINNEST -----------------------------------------------------------------THICKEST -------------->
GAC 800 (specialty polymer) Self-Levelling Gel Clear Tar Gel
Consistency of milk Consistency of heavy cream Consistency of honey
Moderate Clarity Excellent clarity Excellent Clarity
No crazing (thickest pours) Low risk of crazing Moderate risk of crazing
Little to no bubbles Little bubbles Some bubbles
Tape edges when pouring Don't tape edges Don't tape edges
To apply, I pour directly onto my painting, or scoop it out using one of my favourite tools - the Catalyst Art Wedge. You can use anything flat, though, really – an old library card, squeegee, etc. Once poured, I gently smooth it out using the same tool.
If applying the GAC 800, you’ll first want to create a wall around the painting using tape, because it’s so thin it will just spill over the sides. If using the Self-Levelling Gel or Clear Tar Gel, you don’t want to use tape because it can cause something called ‘ crazing’ – when your pour has a rippled effect. It will drip a little off the sides, but not too badly - I just wipe it up as I go.
Bubbles will often come to the surface when doing a pour – I find most so when using Clear Tar Gel. You can poke them with a toothpick, or gently mist isopropyl alcohol from a spray bottle over the wet gel to get rid of them.
If you’re adding a color to any of these mediums to create a glaze, you'll want to use High Flow or Fluid acrylics to keep the thin consistency, and I'd advise mixing gently ahead of time and letting it sit for awhile before pouring. This keeps the consistency smooth, and reduces the bubbles created when mixing.
Remember that acrylic gels and mediums are white when they're wet, but dry clear - so don't panic when it looks like you've spread Titanium White all over your work. It will clear as it dries. This will also effect the color if you've created a glaze - it will look way lighter wet than dry. It will dry to its original color - a good rule of thumb is that the lighter the color when wet, the more transparent it will be.
To answer Denise and Nola, for a textured surface, I would suggest using Clear Tar Gel or GAC 800, if you want a smooth coat across your piece. While the Clear Tar Gel is the thickest, it will likely take at least a couple of pours (with drying time between each layer) to achieve a smooth surface if the piece is very textured (trying to go too thick often results in crazing). With the GAC 800, you can do a deep pour all in one go – the downside being that it doesn’t have quite the clarity of the Clear Tar Gel (I’ve never noticed clarity issues too much myself, though). If doing a deep pour with the GAC 800, remember to build up sturdy tape walls around the piece as the GAC is very thin. Sometimes this can cause a slight lip on the finished pour, but it can just be removed with an Xacto knife
ACRYLIC LIKE ENCAUSTIC
Encaustic is a wax-based paint, made up of beeswax, resin and pigment. I love the soft, veiled look of encaustic, but it requires a big studio setup (tools, ventilation) that I just don't have the space for. You can, however, mimic this look with acrylic mediums, gels and paints.
Any matte medium or gel (matte or semi-gloss) can impart a waxy, encaustic look. The white powder (silica) that is in matte gels and mediums to cut the glossiness can also mimic the soft, hazy translucency of wax. These mediums and gels range in consistency from the pourable Fluid Matte Medium to the super thick and pasty High Solid Gel (Matte).
<-Thinnest --------------------------------------------------------------------------------------Thickest --->
Fluid Matte Matte Medium Soft Gel Regular Gel Heavy Gel Extra Heavy Gel Medium (Semi-Gloss) (Semi-Gloss) (Semi-Gloss) (Semi-Gloss) (Matte) (Matte) (Matte) (Matte)
Adding a small amount of color to matte gels and mediums can enhance the look of the “wax”.
To create a beeswax colored “ wax,” try blending a percent or two of the Interference Gold (Fine) and Quinacridone/Nickel Azo Gold into your gel or medium.
Experiment with different ratios of these and other yellow or brown colors/pigments to get a variety of wax-like colors. You can also mix and match some of the formula ingredients below.
I like applying my “wax” with a palette knife or color shaping tool.
Remember that gels and mediums are milky when wet but will clear as they dry, and a tiny bit of color goes a long way (even if it doesn’t look like it while it’s wet). Iridescent and Interference colors tend to disappear into the wet gel, so it's easy to add too much. Try just dipping the tip of your palette knife into the paint to start.
Here's a link to Golden's article on using acrylic like encaustic, with different formulas you can try (from Just Paint, “ Creating an Encaustic Look with Acrylics”). Most of the quantities in the formulas are quite large, but you can adjust according to how much you need. You can also mix and match the paints and the mediums/gels used.
WORKING ON TOP OF WATERCOLOR and DRY MEDIA
If you're wanting to add an acrylic finish to a watercolor or pencil/pastel piece, it first needs to to be properly fixed so it doesn't smear, as acrylics are waterbased, and watercolors and dry media are watersoluble. Once fixed, you can then work on top with acrylics- including the acrylic finishes above.
The easiest way to fix these mediums is with Golden's Archival Spray Varnish. For the full instruction on varnishing watercolors, check out this technical sheet below.
There’s a few reasons why varnishing your paintings, even if you have applied an acrylic finish, is a good idea if you’re concerned with the longevity of your work.
The two main ones are this:
1) The soft nature of acrylics. Acrylics are a thermoplastic polymer, and so tend to soften in high heat and humidity. That makes them especially susceptible to dirt and dust, which can stick to the acrylic and ultimately become permanently stuck in your painting (mixed media, but not in a good way!)
2) The porous nature of acrylics. Although they don’t look it, acrylics are quite porous, which also make them susceptible to dirt and dust.
Although acrylic gels and mediums can provide great aesthetic effects for your work, they don’t offer the same protection as varnishing does. The reason is that acrylic finishes, like acrylic paint, are permanent. Varnishes, on the other hand, are removable, and protect your work by being a sacrificial layer between your painting and the atmosphere. The way a painting is best cleaned is by removing the old varnish, along with all of the grime, and putting a fresh varnish back on. Gels and mediums, being permanent, don’t offer that protection.
Key characteristics of a varnish include:
1) Being removeable.
2) Being flexible enough to move with the canvas but hard enough to provide a durable, non-tacky surface.
3) Having excellent clarity- not obscuring the image in any way.
4) UV protection.
I'm going to get far more in varnishing in my next post, but hope this first instalment has been helpful! If you have any questions, feel free to leave a comment below, or email me at firstname.lastname@example.org! Also, I'm doing an evening demo/class on varnishing on Wednesday, June 7th at The Art House Cafe if you're interested in learning more about protecting your work. Registration link is below.
Til the next time, happy painting!