Silicone oil is used in acrylic pour painting to create “cells,” those distinctive round, organic patterns that form when colors separate and push through each other on the canvas. A few drops mixed into fluid acrylic paint cause lighter pigments to rise through heavier ones, producing lace-like networks of color that would be nearly impossible to achieve by hand.
How Silicone Oil Creates Cells
The effect comes down to basic physics. Silicone oil changes the density of whichever paint color it’s mixed into, and when paints of different densities interact on a wet canvas, the lighter mixture pushes upward through the heavier one. This is the same fluid dynamic, called Rayleigh-Taylor instability, that governs how oil rises through water or how mushroom clouds form. The lighter paint applies a buoyant force against the heavier paint, and as it breaks through, it creates rounded openings that become the “cells” artists are after.
Silicone oil also has very low surface tension compared to acrylic paint. That mismatch causes the oil to repel the water-based paint around it, forcing colors apart and exposing the layers beneath. The combination of density differences and surface tension repulsion is what gives cells their characteristic multi-ringed appearance, where you can see three or four colors nested inside a single cell.
What It Looks Like in Practice
Without silicone oil, acrylic pours tend to produce a marbled look with smooth, blended color transitions and only small, incidental cells. Adding silicone oil changes the result dramatically. Cells can range from tiny pinpoints to large, sprawling formations depending on how much oil you use, which colors contain it, and how you tilt the canvas afterward.
Tilting the canvas after pouring reshapes and enlarges the cells, pulling them into more organic, irregular forms. Some artists also spritz the wet surface with 91% isopropyl alcohol, which causes cells to grow almost instantly as the alcohol disrupts the surface tension even further. The interplay between these techniques gives artists a surprising degree of control over what is, at its core, a fluid dynamics experiment.
How Much to Use
The standard starting point is 2 to 3 drops of silicone oil per ounce of paint. This is enough to generate visible cells without overwhelming the painting. You don’t add silicone oil to every color in a pour. Most artists choose one or two colors to receive the oil, leaving the others untreated so there’s a clear contrast between cell-forming layers and background colors.
Mixing technique matters as much as quantity. With thin silicone oils (like treadmill lubricant, a popular budget option), you should only stir the paint three to four times after adding the drops. Over-stirring breaks the silicone into tiny, dispersed droplets that produce messy, soap-bubble-sized micro-cells instead of the bold, defined ones most artists want. Thicker oils, like coconut oil, can handle six to eight stirs before breaking down. The goal is to leave the silicone in distinct pockets within the paint rather than fully incorporating it.
Silicone Oil in Commercial Paints
Silicone oil isn’t only an additive that artists introduce themselves. Paint manufacturers have used silicone-based compounds (polydimethylsiloxanes) as defoamers in acrylic emulsion paints for decades. Acrylic paint naturally tends to foam during manufacturing because it contains surfactants, and silicone oils are highly efficient at moving to the surface and releasing trapped air bubbles. This is why some acrylic paints produce cells even without added silicone: they already contain trace amounts from the manufacturing process. Titanium white is famously cell-friendly for this reason, as it’s a dense, heavily formulated paint that often contains more defoaming agents.
The Varnishing Problem
The biggest practical challenge with silicone oil is what happens after the painting dries. Silicone is hydrophobic, meaning it repels water. When you try to apply a water-based acrylic varnish over a painting that contains silicone residue, the varnish pools away from the oily spots, leaving dry patches and an uneven finish. This can happen even months after the painting has dried and the surface looks visually clean of oil.
The standard approach is to let the painting cure for at least three weeks, then wipe the entire surface with isopropyl alcohol to remove as much residual silicone as possible. Some artists repeat this cleaning step several times. Even after thorough cleaning, water-based varnishes sometimes still won’t adhere properly. In those cases, a spray-on clear coat enamel (solvent-based rather than water-based) tends to bond more reliably, since it isn’t repelled by silicone residue the same way.
Skipping the varnish step entirely isn’t a great option. Unvarnished acrylic pours are vulnerable to dust adhesion, UV damage, and surface scuffing, and any remaining silicone oil on the surface will attract and hold dust over time.
Long-Term Durability Concerns
Conservation researchers have noted that silicone oils in acrylic paint films can produce defects known as craters and fisheyes, small depressions or pinholes where the silicone has disrupted the paint’s ability to form a smooth, continuous surface. In manufactured paints, formulators carefully control silicone levels to avoid these problems. When artists add their own silicone oil, they’re working outside those tested ratios, and the long-term behavior of the paint film is less predictable.
The silicone itself doesn’t yellow or degrade significantly over time, which is part of why it’s used industrially. But because it never fully bonds with the acrylic polymer, it remains a separate substance trapped within or sitting on top of the paint layer. This is why residue continues to migrate to the surface weeks or months after pouring, and why varnish adhesion remains a persistent issue. For artists selling work or wanting pieces to last decades, thorough surface cleaning and proper varnishing are essential steps that shouldn’t be skipped.
Alternatives to Silicone Oil
Artists who want cells without the varnishing headaches sometimes use dimethicone (found in hair serums), which is chemically similar but comes in different viscosities that can be easier to control. Others use isopropyl alcohol alone, spritzed onto the wet surface, which creates cells through surface tension disruption without leaving an oily residue. The cells from alcohol tend to be less dramatic and defined than silicone-produced ones, but the finished painting is much easier to seal and protect.
Heat is another cell-producing tool. Passing a torch or heat gun briefly over a wet pour causes the top layer to warm and thin, allowing buried colors to rise through. Many artists combine a small amount of silicone oil with a torch pass to get bold, well-defined cells while using less oil overall, reducing the residue they’ll need to clean later.