Panel Line Washing:
The Complete Beginner's Guide
The fastest way to make any Gunpla or scale model look dramatically more realistic — and you can do it in under an hour on your very first try.
Panel line washing is the technique that separates a freshly built kit from a finished model. It takes the flat, uniform plastic surface that comes out of the box and gives it depth, shadow, and structure — the visual difference between a toy and a display piece. If you've ever looked at a photo of someone else's Gunpla or armor model and wondered what they did to make it look so real, this is usually a large part of the answer.
This guide covers everything: what panel lining actually does, which liner to use for which kit type, how to apply it correctly, and how to fix the mistakes that every beginner makes the first time. By the end, you'll have everything you need to panel line your next build with confidence.
What Panel Line Washing Actually Does
Scale models — and Gunpla especially — are covered in engraved recesses: the lines, joints, vents, and mechanical details that define the surface. Under flat overhead light, those recesses are nearly invisible. Panel line washing fills those recesses with a thin, dark fluid that dries in place, creating the visual shadow that makes every detail pop.
The result looks like the model is lit from above — because in real life, recesses catch shadow. The wash mimics that shadow artificially, making the model appear more three-dimensional and believable at any viewing distance.
Panel lining is not painting. You're not changing the color of the surface — you're adding shadow to the structure that already exists. A single panel line wash session can take a model from "finished kit" to "finished model" in less than an hour.
The Two Types of Panel Liner: Water-Based vs Enamel
This is the first decision every builder has to make, and it matters more than most beginners realize. Panel liners come in two main formulations, each with real advantages and one critical trade-off.
Thins and cleans up with water. Safe on bare plastic, safe on acrylic paint. Easy to wipe away with a damp cloth or cotton swab while wet. No solvent risk. The recommended starting point for most builders.
Thins and cleans up with enamel thinner. Flows exceptionally well into recesses. Best removed with lighter fluid or enamel thinner. Risk of cracking bare plastic if applied without a protective coat underneath.
Never apply enamel panel liner directly to bare, uncoated plastic. The thinner used to remove it can seep into stressed plastic and cause stress fractures — especially at joints and connection points. Always apply a clear matte coat first, or use a water-based liner instead.
For most builders — especially beginners and Gunpla builders working on kits without primer — water-based panel liner is the right choice. It's safer, easier to control, and produces excellent results without any risk to the kit underneath.
The Stedi Acrylic Panel Liner: What Makes It Different
The Stedi Acrylic Panel Liner has become one of the most popular water-based options in the Gunpla and scale modeling community, and for good reason. It's engineered specifically for recessed panel line work — not a generic wash repurposed for the task.
It uses an acrylic formula with a surface tension optimized for capillary flow. In practical terms, this means it pulls itself into recesses with minimal encouragement — touch the brush to the start of a panel line and the liquid travels along it naturally. You don't need to push it; you need to guide it.
| Color | Best Used On | Effect |
|---|---|---|
| Black | Light grey, white, bright colors | Maximum contrast, deep shadows |
| Dark Brown | Military armor, earth tones, sand | Natural shadow, weathered look |
| Dark Grey | Blue, purple, green, mid-tone bases | Subtle shadow, less stark than black |
| Olive | Military vehicles, green schemes | Tonal depth without high contrast |
| Dark Blue | White Gunpla, blue mecha | Cooler shadow, popular for RX-78 style builds |
Stedi also offers a fluorescent panel liner range — ideal for sci-fi builds, mecha models, and anything where you want glowing accent lines under UV light. The UV Light + Fluorescent Panel Liner Set bundles the paint and light together for a complete solution.
How to Apply Panel Liner: Step by Step
The technique is simple. The details are what separate a clean result from a messy one.
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Prepare the surface. The kit should be clean, dust-free, and — if you're using an enamel liner — sealed with a clear matte coat. For Stedi acrylic liner, bare plastic is fine. Handle parts by the edges to avoid oils from your fingertips.
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Load the brush lightly. Dip a fine-tipped panel liner brush into the liner. Wipe off the excess on the rim of the bottle — you want a loaded tip, not a dripping one. Too much liner makes cleanup much harder.
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Touch the brush to the recess, not the surface. Place the very tip of the brush at the start of a panel line and hold it there for a second. The capillary action will pull the liner along the recess automatically. Let it flow — don't drag or push. Move the brush gently to guide it around corners if needed.
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Work one section at a time. Do all the panel lines on one face of a part before moving to the next. This lets the liner stay workable — wet liner is much easier to clean up than dried liner.
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Let it dry partially — not fully. Wait 5–10 minutes until the liner is no longer wet but hasn't fully hardened. This is the ideal window for cleanup. Fully wet liner smears; fully dry liner requires more effort to remove cleanly.
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Clean up with a cotton swab. Use a cotton swab slightly dampened with water (for Stedi acrylic) to wipe away the liner from the flat surfaces surrounding the recesses. Use gentle, single-direction strokes. The recesses will hold the liner; the flat surfaces will clean up easily.
Water-Based vs Enamel: Application Differences
- Safe on bare plastic and acrylic paint
- Clean up with water or damp swab
- Re-workable while wet
- Ideal for beginners and Gunpla
- No protective coat required first
- Slightly less flow than enamel
- Exceptional capillary flow
- Clean up with enamel thinner or lighter fluid
- Requires sealed surface underneath
- Risk of cracking bare plastic
- Stronger odor, more ventilation needed
- Better for experienced builders
Common Mistakes and How to Fix Them
Work in smaller sections and don't leave the liner to dry fully. If it does dry, dampen the swab more and use patience — don't scrub. For Stedi acrylic, a slightly wetter swab will usually reactivate it enough to wipe cleanly.
Too much liner on the brush, or liner applied directly to the surface instead of the recess. Use less material and apply it to the edge of the recess first, letting capillary action do the work.
The recess may be too shallow, the liner too thick, or the kit surface too waxy (common on fresh Bandai plastic). Thin the liner slightly with a drop of water, or clean the surface with isopropyl alcohol first to remove mold release residue.
The swab has too much liner on it. After each pass, rotate to a clean section of the swab — or use a fresh one. Never re-use the same dirty section of swab on a clean area.
Pro Tips for Cleaner Results
The tip geometry matters. DSPIAE panel liner brushes are designed to hold the right amount of liner and release it at the tip with precision. A regular watercolor brush holds too much and gives you less control.
Black works on light-colored kits. On dark blue or green kits, a dark grey or olive liner gives a more natural result. The goal is a shadow, not a harsh outline.
Apply your panel liner before placing waterslide decals. Liner cleanup requires light moisture and pressure — both of which can damage decals that aren't fully settled and sealed.
A final coat of clear matte varnish locks in the liner, protects the surface, and unifies the overall finish. It also eliminates any sheen difference between lined and unlined areas.
Everything mentioned in this guide — in one place
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