# Glaze Medium, Flow Improver and Retarder: What Each One Does for Minis Source: https://minipaintlab.com/blog/glaze-medium-flow-improver-retarder-minis Published: 2026-10-28 Publisher: Mini Paint Lab Painting mediums are additives that change how acrylic paint behaves without changing its color much. Glaze medium makes paint more transparent so you can build thin tints, flow improver helps paint move smoothly and level out, and retarder slows drying so you have longer to blend. They are optional, and plenty of excellent painters use only water. Still, they solve specific problems that water makes worse, such as chalky, weak paint when you dilute too far. This guide explains what each medium does, how to use it, how much to start with, what mistakes to avoid and how to decide which ones, if any, are worth adding to your bench. ## Why not just use water Water is the simplest thinner and it works well in small amounts. The trouble starts when you add a lot, because water weakens the binder that holds pigment to the model. Heavily watered paint can turn chalky, dry patchy and lose its grip on the surface, and it may pool in recesses instead of flowing smoothly. Mediums replace some of the water with extra binder or surface-active ingredients so the paint stays thin without losing its film strength. They are not magic, and good technique still matters, but they widen the range of consistencies you can use reliably. ## Glaze medium: transparent color for smooth transitions A glaze medium is a clear acrylic binder, usually sold in a matte or gloss version. Mixed with a small drop of paint, it makes a translucent tint that you can layer over an area to shift its color or soften a transition. Because the paint is mostly medium, it keeps its film strength even when it is very transparent. Use it for smoothing gradients on armor, cloaks and skin, tinting shadows, and creating subtle color shifts. Start with mostly medium and a little paint, then build up slowly with several thin coats. Let each layer dry before applying the next, otherwise you may lift the earlier coat. Choose a matte medium if you want to avoid a shiny film. ## Flow improver: smoother paint with less streaking Flow improver, sometimes called a flow aid, reduces the surface tension of paint so it spreads and levels more evenly. It helps thinned paint behave better, with fewer brush marks and less beading. Many airbrush painters use it to reduce tip dry and spitting, and it is also helpful for brush painting on smooth surfaces. Use only a tiny amount, often a drop or two in a palette mix, and test before using it on a model. Too much can make paint slippery, reduce coverage or encourage it to run into places you did not intend. It is best treated as a seasoning rather than an ingredient. ## Retarder: a little more time to blend Retarder slows down how quickly paint dries, which gives you longer to blend wet paint on the model. This is helpful for wet blending, feathering and smooth gradients on larger surfaces, where fast-drying acrylics can make the transition hard to control. It is less useful for fine detail, where fast drying is a benefit. Use a very small amount, because too much can leave paint tacky for a long time and make it prone to smudging. Warm, dry rooms shorten working time, so retarder can be especially helpful there. Always follow the manufacturer's directions, since different products have different recommended ratios. ## How much to use and how to test Start with small ratios, such as one drop of medium to a few drops of paint, and adjust slowly. Make a test patch on a spare piece of plastic or a primed offcut so you can see how the mix dries and behaves. Compare it with the same paint thinned with water alone to see the difference. Different brands vary, so mediums from one maker may not behave the same as another. Mixing a medium made for the same paint line is usually the safest choice, but cross-brand mixing often works too, as long as both are water-based acrylics. If a mix curdles or separates, stop and use something else. ## Mistakes and limits Mediums do not replace practice. A glaze applied too thick will look streaky, and a blend started too late will still look rough. Do not expect a medium to fix poor brush control or dirty brushes. Clean tools and thin layers do most of the work. Also avoid using too many different additives at once. Mixing glaze medium, flow improver and retarder in the same pot can make the paint unpredictable and harder to troubleshoot. If something goes wrong, change one thing at a time so you can see what caused the problem. ## Storing and handling mediums Keep mediums in sealed bottles away from heat and freezing temperatures, and shake or stir them gently before use. Some mediums look milky in the bottle and dry clear, which is normal, but if a medium turns lumpy, smells off or will not mix smoothly, replace it. Use a clean stick or a dropper rather than dipping a loaded brush into the bottle. On the palette, mix mediums with paint rather than painting them straight onto the model, unless the product directions say otherwise. A wet palette will keep the mix workable, but avoid adding extra water on top of a medium, since it can upset the balance and make the paint thin and weak. ## Which ones are worth buying If you only buy one, many painters pick glaze medium, since it expands what you can do with transparency. Flow improver is a good second choice for airbrush users, and retarder suits those who enjoy smooth blending on larger models. If you rarely blend or glaze, you may not need any of them. Check whether your paint range includes mediums, as some makers sell matching products. Buy small bottles first, since a little goes a long way and you can see whether they suit your style before investing more. ## Related buying guides - https://minipaintlab.com/best/best-miniature-paint-sets - https://minipaintlab.com/best/best-wet-palettes - https://minipaintlab.com/best/best-acrylic-inks-minis - https://minipaintlab.com/best/best-paint-mixing-tools