Quick answer: Liquitex acrylic mediums are added to paint, not used instead of it. Squeeze paint onto the palette, add medium a little at a time (anywhere from 10 percent for a slight change in flow to several parts medium per part paint for a transparent glaze), mix until uniform, and apply. Fluid mediums thin paint and change sheen; gels and paste thicken it; retarder slows drying; pouring medium makes it level. There is no upper limit, because medium is the same binder the paint is made from.
Working out how to use Liquitex acrylic medium is mostly a matter of knowing which bottle does what, because the brand sells more than twenty of them and the labels assume you already know the difference between a fluid medium and a gel. Once the categories are clear, the method is the same across the board: mix with paint, test on scrap, adjust.
The steps below cover the general mixing procedure first, then walk through each major Liquitex medium with ratios, drying times, and the jobs it does best. A troubleshooting section follows for the mistakes that come up most. The paint itself matters too; most people learning mediums are working with the student range, and the guide to Liquitex BASICS acrylic paint and how to get the most from it explains how that paint behaves before anything is added.
What an acrylic medium is
Acrylic paint is pigment suspended in an acrylic polymer emulsion. An acrylic medium is that same emulsion without the pigment, sometimes modified with thickeners, matting agents, or retarding additives. Because medium and paint share a binder, mixing them cannot weaken the paint film the way adding water can. Water dilutes the binder; medium replaces pigment with more binder.
That is why the usual advice is to thin acrylic with medium past a certain point. Liquitex and most manufacturers suggest keeping water to no more than about 25 to 30 percent of a mix. Beyond that, the dried film may be underbound: chalky, weak, and prone to lifting. Medium has no such ceiling.
The general method for any Liquitex medium
- Put paint out first. Squeeze or pour the color onto a non-absorbent palette.
- Add medium in small increments. Start with a quantity about a quarter the size of the paint blob. You can always add more; you cannot take it out.
- Mix thoroughly. Use a palette knife, not a brush, and fold until the color and medium are completely uniform. Streaks of unmixed medium show up as glossy or transparent patches when dry.
- Test on scrap. Brush a swatch on a piece of primed paper or canvas. Fluid mediums look milky wet and dry clear, so the wet appearance is misleading.
- Adjust. More medium for more transparency, flow, or body; more paint for more color strength.
- Apply, then clean up with water. Mediums dry as hard as paint and will ruin brushes just as quickly.
Two general rules apply to every medium. First, most Liquitex mediums are white or milky in the bottle and dry clear, so judge results only after drying. Second, thick applications of any medium take far longer to dry than paint alone: a quarter-inch layer of gel may need several days to cure fully.
Fluid mediums: thinning, glazing, and sheen
Gloss Medium (and Gloss Medium & Varnish)
A thin, pourable medium that increases flow, transparency, and shine. Common uses:
- Glazing: mix 1 part paint to 3 to 10 parts medium, depending on how faint you want the veil of color. Brush thinly over a dry layer. Each glaze shifts the color beneath without hiding it.
- Extending paint: 1 part paint to 1 part medium stretches expensive colors with only a mild loss of coverage.
- Improving adhesion: a little gloss medium in paint helps it bond to slick surfaces.
- Collage adhesive: brush on both surfaces, press together, and let dry.
- Isolation coat: a layer of gloss medium over a finished painting, allowed to dry 24 hours, before a removable varnish.
Dry time is roughly 10 to 20 minutes for thin layers. It dries glossy, which deepens dark colors.
Matte Medium
The same emulsion with a matting agent added. It thins paint and increases transparency like gloss medium but dries to a flat, non-reflective finish. Use it when glare is a problem, for a chalky or velvety look, or to even out the sheen of a painting with mixed glossy and matte areas. Matte medium is slightly more opaque than gloss when dry, so very thin glazes made with it can look faintly cloudy over dark colors. It also works as a collage adhesive and as a ground for drawing media, since the matte surface accepts pencil and pastel.
Ultra Matte Medium
A heavier matting load. It can be mixed with paint up to roughly 1:1 before the color starts to look noticeably lighter and chalkier. Useful as an extender when you want to stretch paint without adding gloss.
Glazing Medium
Formulated to flow smoothly and dry with a soft gloss. Mix 1 part paint to anywhere from 2 to 10 parts medium for glazes. It also slows drying slightly compared with plain gloss medium, which gives a little more time to brush out an even layer.
Flow Aid (Flow Improver)
This one is different: it is a surfactant additive, not a binder. It must be diluted first, roughly 1 part Flow Aid to 20 parts water, and that solution is then used in place of plain water to thin paint. It reduces surface tension so paint spreads evenly and levels without brush marks. Never add it straight from the bottle to paint, and do not exceed the recommended dilution; too much weakens the film.
Gel mediums: body and texture
Gels are the same binder thickened to a paste. Liquitex sells them in gloss, matte, and semi-gloss, and in several viscosities.
| Gel | Consistency | Typical ratio with paint | Main jobs | Dry time (1/8 in layer) |
|---|---|---|---|---|
| Gel Medium (regular) | Like heavy body paint | 1:1 to 1:3 (paint:gel) | Extending paint without thinning, light impasto, collage with heavier papers | 1–3 hours |
| Heavy Gel | Thick, holds peaks | 1:1 to 1:5 | Impasto, knife work, embedding small objects | 4–12 hours |
| Super Heavy Gel | Very stiff | 1:2 to 1:10 | Sculptural texture, sharp peaks that do not slump | 12–48 hours |
| Clear Tar Gel | Stringy, self-leveling | Tint lightly: 1:10 or less | Drizzled lines, drips, glass-like films | 2–6 hours |
| String Gel | Similar to tar gel, more stretch | Tint lightly | Fine drizzled lines | 2–6 hours |
| Self-Leveling Gel | Pourable, settles flat | 1:5 to 1:10 | Smooth resin-like coats, flat glazes | 6–24 hours |
Gels dry clear (gloss) or translucent (matte), so adding a lot of gel to a color makes it more transparent as well as thicker. If you want thick and opaque, add less gel and more paint, or use modeling paste instead.
Gels shrink as they dry, roughly 20 to 30 percent in height for the thicker ones. Peaks soften and edges pull back. Build very thick texture in two or three layers, letting each firm up, rather than in one application.
Modeling Paste: opaque texture
Modeling Paste (and Light and Flexible Modeling Paste) is acrylic binder loaded with marble dust or similar fillers. Unlike gels it dries white and opaque, with a hard, sandable surface.
- Apply with a palette knife directly to primed canvas or panel in layers up to about a quarter inch each.
- Let it dry fully (a day or more for thick layers), then paint over it, or tint it before application by mixing in paint. Tinted paste dries lighter than it looks wet because of the white filler.
- Carve, stamp, or comb it while wet for texture; sand it when dry for a smooth relief.
- Use Flexible Modeling Paste on stretched canvas, which moves. Standard paste can crack if the support flexes.
Pouring Medium
Pouring Medium is a fluid binder designed to flow, level itself, and dry without crazing (the fine cracks that plain paint develops when poured thick). The standard starting ratio is 1 part paint to 2 to 3 parts medium for soft body paint, and 1 part to 3 or 4 parts for heavy body, adjusted until the mix runs off a stir stick in a smooth ribbon.
- Mix each color with medium in its own cup. Stir slowly to avoid bubbles.
- Level the canvas and raise it on cups so excess can run off the edges.
- Pour colors in puddles, stripes, or layered in one cup for a dirty pour.
- Tilt the canvas to spread. Do not use a brush.
- Leave flat, covered against dust, for 24 to 72 hours. Thick pours may take a week to cure.
Liquitex Pouring Medium dries to a high gloss. Adding water to a pour mix is a common cause of cracking; use more medium instead if the mix is too thick.
Slow-Dri and Retarder
Two products extend working time:
- Slow-Dri Fluid Medium / Slow-Dri Gel: full-strength binders with a retarding additive. Mix with paint in any proportion. They roughly double open time while keeping the film strong.
- Slow-Dri Fluid Retarder (additive): a concentrated additive without binder. Keep it to about 15 percent or less of the paint volume. Too much leaves a film that stays soft and tacky for days or never fully cures.
Use either when blending gradients, painting wet-into-wet, or working in a hot, dry room. Note that slowed paint stays re-wettable longer as well, so a second layer applied too soon can lift the first.
Gesso and primers
Liquitex Gesso is often grouped with mediums. It is binder with chalk and titanium white, applied as a ground. Two coats, brushed in perpendicular directions and sanded lightly between, give a smooth absorbent surface on canvas, wood, or paper. Clear Gesso adds tooth without hiding the surface; Super Heavy Gesso can be textured like paste. Gesso can be tinted with a little acrylic paint for a colored ground.
Varnishes: mediums for finishing
Gloss Medium & Varnish doubles as a permanent, non-removable topcoat. Liquitex’s dedicated Gloss, Matte, and Satin Varnishes are also permanent acrylic finishes; Soluvar is the removable solvent-based option conservators prefer. The standard sequence for a finished acrylic painting is: wait at least 72 hours after the last paint layer, apply an isolation coat of gloss medium thinned with a little water, let it dry 24 hours, then varnish in two thin coats. Matte varnish over very dark colors can leave a frosted look, so test first.
Common mistakes with Liquitex mediums
| Problem | Cause | Fix |
|---|---|---|
| Cloudy or milky dried glaze | Layer applied too thick, or medium not fully cured | Apply thinner layers; wait longer; gloss stays clearer than matte |
| Cracks in a pour or thick gel | Water added; layer too thick; dried too fast | Use medium not water; build in layers; dry slowly away from heat |
| Tacky surface after days | Too much retarder or extremely thick layer | Keep retarder under 15%; allow weeks for thick gels; cannot be reversed if badly over-retarded |
| Texture slumped flat | Regular gel used where heavy gel was needed | Use Heavy or Super Heavy Gel; build in stages |
| Chalky, weak paint film | Thinned with water past 30% | Thin with fluid medium instead |
| Streaks of gloss in a matte painting | Medium not fully mixed with paint | Mix with a knife until uniform |
| Color much lighter than expected | Modeling paste or ultra matte medium diluting the pigment | Add more paint or paint over the dried texture instead |
Which medium to reach for
- To thin paint without weakening it: Gloss or Matte Medium.
- To glaze: Glazing Medium or Gloss Medium.
- To remove brush marks: Flow Aid solution in place of water.
- To thicken for impasto: Heavy Gel (transparent) or Modeling Paste (opaque).
- To pour: Pouring Medium.
- To blend longer: Slow-Dri medium or Retarder.
- To stick collage down: Matte or Gloss Medium.
- To prime: Gesso.
- To finish: isolation coat of Gloss Medium, then varnish.
FAQs
How much Liquitex medium should I add to acrylic paint?
There is no maximum because medium is the same binder as the paint. Start around one part medium to four parts paint for a subtle change, and go to several parts medium per part paint for glazes or pours. Judge by test swatches after drying.
Can I use Liquitex medium instead of water?
Yes, and for anything beyond slight thinning you should. Water over about 25 to 30 percent weakens the paint film; medium does not.
Does Liquitex matte medium dry clear?
It dries translucent rather than fully clear. In thin layers it is nearly invisible; in thick layers or over dark colors it can look slightly frosted. Gloss medium dries clearer.
Can Liquitex mediums be used with other brands of acrylic?
Yes. Artist acrylics from different brands share compatible acrylic binders. Results may vary slightly in sheen and drying time, so test first.
How long does Liquitex gel medium take to dry?
Thin coats dry in an hour or two. Layers around an eighth of an inch take 4 to 12 hours to feel dry and can take days to cure fully. Super Heavy Gel in thick applications may need a week.
Is Liquitex gloss medium the same as varnish?
Gloss Medium & Varnish can serve as a permanent topcoat, but it is not removable. A removable varnish such as Soluvar, applied over an isolation coat of gloss medium, is the archival approach.
Next Step
Every Liquitex medium follows the same logic: it is paint without pigment, so it changes how paint handles without changing what it is made of. Pick the medium by the job (thin, glaze, thicken, pour, slow, prime, finish), add it gradually, mix completely, and judge the result dry rather than wet.
Mediums reveal their effects most clearly on paint you already understand. If you are working with the student line, the guide to Liquitex BASICS colors, consistency, and best uses explains how that paint behaves on its own, which makes it much easier to see what each medium adds.
