Quick answer: Depending on what the medium was for, you can use water for light thinning, a different acrylic product you already own (gesso, varnish, another gel or paint) for some jobs, or household items like PVA glue, glycerin or cornstarch paste for practice work. Household substitutes are fine for experiments and kids’ crafts, but they are not archival and can yellow, crack or stay water-sensitive. For paintings you want to last, a real acrylic medium is the safer choice.
You are mid-painting, the glaze needs medium, and the jar is empty. Or you are just starting out and want to know whether you need to buy medium at all. “What can I use instead of acrylic medium” has several honest answers, because the right substitute depends on the job the medium was supposed to do.
Below, substitutes are grouped by purpose: thinning, glazing, thickening, slowing drying, pouring, gluing and sealing. Each comes with trade-offs, so you can decide what is acceptable for a sketch versus a finished piece. If you would rather stock up on the real thing, our comparison of the best acrylic paint medium sets rounds up multi-medium kits.
First, Know What Acrylic Medium Actually Is
Most acrylic mediums are clear acrylic polymer emulsion, the same binder found in acrylic paint, sometimes with additives that control thickness, sheen, flow or drying time. When you add medium to paint, you add more binder along with any special properties.
That is the key to judging any substitute. A good substitute should either contain compatible acrylic binder, or be used in such small amounts that it does not compromise the paint film. Anything that replaces binder with something weaker, such as starch, soap or glue that stays water-soluble, shortens the life of the painting.
Substitutes at a Glance
| What you need | Substitute | Archival? | Best for |
|---|---|---|---|
| Thinning | Water (modest amounts) | Yes, within limits | Washes, light flow adjustment |
| Glazing | Gloss or satin acrylic varnish (water-based, non-removable type) | Generally | Transparent layers |
| Glazing / extending | Clear acrylic sealer or clear acrylic craft medium | Varies | Craft projects |
| Thickening | Acrylic gesso or modeling paste | Yes | Opaque texture |
| Thickening | Cornstarch paste | No | Kids’ crafts, practice |
| Slower drying | Glycerin (tiny amounts) | Questionable | Short experiments |
| Slower drying | Misting, stay-wet palette | Yes | Any painting |
| Pouring | PVA glue and water | No | Practice pours |
| Gluing collage | PVA glue or decoupage medium | Varies | Journals, crafts |
| Sealing | Acrylic varnish or clear acrylic spray | Yes | Protecting finished work |
Substitutes for Thinning Acrylic Paint
Water
Water is the most common stand-in, and it is perfectly fine in modest amounts. It dilutes binder, so heavy thinning on non-absorbent surfaces can leave a weak, chalky or uneven film. A rough guideline many painters follow is to keep water to around a quarter or a third of the mix on primed surfaces, and to use more freely on absorbent paper. Treat that as a rule of thumb rather than a hard limit.
Flow improver alternatives
Some painters add a drop of mild dish soap to water to reduce surface tension, mimicking flow improver. It can help paint spread, but soap residues may affect adhesion and film quality over time. Keep it for practice work, and use a proper flow aid for paintings you intend to keep.
Thinner acrylic paint
Fluid or high-flow acrylics are already thin. Mixing a little into heavy-body paint thins it without adding water. This is an easy fix if you happen to have a bottle of fluid color in a similar hue, or fluid titanium white for lighter mixes.
Substitutes for Glazing Medium
Water-based acrylic varnish
Some painters mix a small amount of paint into a non-removable gloss or satin acrylic polymer varnish to make glazes. Since it is still acrylic polymer, it bonds with the paint layer. Be careful with removable varnishes, which are designed to be dissolved later; using them inside paint layers can create problems if the painting is ever cleaned. Check the label.
Clear acrylic gel or sealer you already own
If you have any clear acrylic gel, sealer or “clear medium” from craft supplies, it may work for glazing. Results vary by formula. Test on scrap and check that it dries clear and non-tacky.
Thinned transparent paint
For very light glazes, a transparent pigment thinned with a little water may be enough on an absorbent surface. On top of slick acrylic layers, it may bead or lift, so apply gently and let it dry before touching it again.
Substitutes for Gel Medium and Thickeners
Acrylic gesso
Gesso is thick and acrylic-based. Mixing it with paint gives body and a matte finish, but it also lightens colors because most gesso is white. Clear gesso exists and lightens less, though it often has a toothy texture.
Modeling paste
If you own modeling paste, it thickens paint for texture. Like gesso, it makes colors more pastel and dries opaque.
Cornstarch paste
Cooking a little cornstarch with water into a thick paste and mixing it with acrylic paint creates a cheap impasto-style mixture. It is popular for kids’ crafts. It is not archival: starch can attract mold, crack and weaken the film. Keep it for temporary projects.
Baking soda or fine sand
Adding baking soda, fine sand or similar fillers to paint creates gritty texture. These can be fine for decorative pieces, but they change the paint’s flexibility and may cause flaking on flexible canvas.
Substitutes for Retarder or Slow-Drying Medium
Glycerin
Glycerin is a humectant and is a component of some commercial retarders. Adding a very small amount, often described as a few drops per palette of paint, can extend working time. Too much can leave paint tacky and slow to cure. Results vary, so test before using it in a painting you care about.
Misting and stay-wet palettes
The most reliable no-cost alternative: lightly mist your palette and canvas with water as you work, and use a stay-wet palette (a damp sponge or paper towel under parchment paper in a lidded tray). These slow evaporation without changing paint chemistry.
Work environment
Painting in a cooler, more humid room, away from fans, heaters and direct sun, can noticeably increase working time.
Substitutes for Pouring Medium
The most common DIY pouring mix is PVA craft glue thinned with water, mixed with acrylic paint. It flows well and is cheap, which is why many beginners start with it.
The trade-offs are real. PVA can remain somewhat water-sensitive, may yellow over time, and can cause crazing or cracking, especially in thicker pours. It is fine for learning cell formation and color combinations. For pieces you plan to sell or keep long-term, a dedicated acrylic pouring medium is the more durable choice.
Substitutes for Collage and Adhesive Mediums
- PVA glue: Works for paper collage in sketchbooks and journals. Over time it can yellow and may not be fully archival.
- Decoupage medium: Designed for sealing and gluing paper. Convenient, though some formulas stay slightly tacky or soften in humidity.
- Acrylic gloss or matte varnish (non-removable): Can glue light papers when brushed under and over them.
- Acrylic paint itself: A thick layer of paint can hold lightweight paper in place.
Substitutes for Sealing or Isolation Coats
An acrylic varnish or clear acrylic spray can stand in for a gloss or matte medium coat over a finished painting. Many sprays are solvent-based, so use them outdoors or with good ventilation and test them on a sample to make sure they do not lift or cloud the paint.
Avoid using household sealers such as floor polish or furniture finishes on artwork. They are not designed for paint films and can yellow, become brittle or react unpredictably.
Starting Ratios for Common DIY Substitutes
If you decide to experiment, these starting points are frequently shared among hobby painters. They are not manufacturer recommendations, so test before using them on anything important.
| DIY mix | Starting proportion | Notes |
|---|---|---|
| Water thinning | Up to roughly 1 part water to 3 parts paint on primed surfaces | Use more freely on absorbent paper |
| PVA pouring mix | Often around 1 part PVA to 1 part water, then mixed with paint | Adjust to a warm-honey consistency |
| Glycerin retarder | A few drops per tablespoon of paint | Too much leaves paint tacky |
| Cornstarch thickener | Cooked paste mixed about 1 : 1 with paint | Temporary projects only |
| Gesso thickener | 1 part gesso to 2 parts paint | Lightens and mattes color |
Why Archival Quality Matters
“Archival” means a material is expected to stay stable for a long time: it should not yellow significantly, become brittle, attract pests or lose adhesion. Artist-grade acrylic mediums are formulated with that goal, which is why they cost more than craft glue.
Household substitutes were not designed with artwork in mind. Some PVA glues remain partly water-soluble, so humidity can soften them. Starches are food for mold and insects. Soaps leave residues that interfere with how layers bond. None of this will ruin a practice sketch, but it can cause problems years later in a painting you care about.
What Not to Use Instead of Acrylic Medium
- Oil-based products such as linseed oil or oil mediums. They do not mix with water-based acrylics and can prevent adhesion.
- Solvents like mineral spirits or turpentine. They can damage acrylic films and are unnecessary.
- Large amounts of dish soap. Leaves residue and weakens the film.
- Flour paste. Attracts pests and mold and cracks as it dries.
- Hairspray as a final sealer. Not designed for artwork; may yellow or stay sticky.
When a DIY Substitute Is Fine
- Practice paintings and studies
- Kids’ art activities and classroom crafts
- Experiments with pouring techniques or textures
- Sketchbook or journal pages
- Temporary decorations and props
When You Should Use Real Acrylic Medium
- Commissioned or sold artwork
- Paintings meant to hang for years
- Heavy glazing or layered techniques
- Large pours that need a flexible, crack-resistant film
- Work on flexible surfaces like stretched canvas
A starter set covering gloss medium, matte medium and a gel handles most of those situations. See our guide to acrylic medium sets for beginners and pros if you are deciding what to buy.
Quick Decision Guide
- Just need paint a bit thinner? Use a little water.
- Need transparent glazes now? Try a non-removable acrylic gloss varnish or clear acrylic you already own, and test first.
- Need texture? Use gesso or modeling paste if you have it, accepting lighter colors.
- Paint drying too fast? Mist, use a stay-wet palette and adjust the room before reaching for glycerin.
- Want to try pouring cheaply? Practice with PVA glue mixes, but switch to pouring medium for keepers.
- Need to glue paper? PVA or decoupage medium for journals; acrylic medium for archival pieces.
Testing a Substitute Before You Commit
Whatever you choose, a simple test protects your painting:
- Paint a swatch with the substitute mix on the same surface you plan to use.
- Let it dry at least overnight.
- Check for cracking, cloudiness, stickiness or color shifts.
- Rub gently with a damp cloth to see if color lifts.
- Flex the surface slightly if it is canvas or paper.
- Leave a second swatch in a sunny window for a few weeks if you want a rough sense of yellowing.
FAQs
Can I use water instead of acrylic medium?
Yes, for light thinning. Heavy dilution on non-absorbent surfaces can weaken the film, so medium is better for glazes and pours.
Can I use Mod Podge as acrylic medium?
Decoupage medium can act as a glue and sealer in crafts and journals. It is not identical to artist acrylic medium and may not be as durable or archival, so test it first.
Can I use PVA glue as a pouring medium?
Many beginners do for practice. It can yellow, crack or remain water-sensitive over time, so dedicated pouring medium is better for finished work.
Can I use gesso as a medium?
Gesso can thicken paint and add tooth, but it lightens colors and dries matte. Clear gesso lightens less but adds texture.
What household item slows acrylic drying?
A few drops of glycerin is the most common household option, though results vary. Misting and a stay-wet palette are more predictable.
Can I use varnish instead of gloss medium?
A non-removable acrylic polymer varnish can often stand in for gloss medium. Avoid using removable varnishes inside paint layers.
Final Thoughts
The best answer to “what can I use instead of acrylic medium” depends on the job. Water handles light thinning, products you already own may cover glazing or texture, and household items work for practice and crafts. For lasting results, though, nothing replaces real acrylic binder. When you are ready to build a dependable toolkit, compare kits in our roundup of top acrylic paint medium sets.
