Gunpla Panel Lining: How to Make Your Builds Pop

Originally published in January 2023, updated on May 2026.

Panel lining is the process of filling in the recessed lines on your Gunpla kit's surface with ink or paint so the surface detail actually shows up. Every kit has these grooves molded in - they represent armor seams, hatches, vents, mechanical detail - but on a bare build, they're nearly invisible under normal lighting. Fill them in with a darker color, and suddenly the whole kit looks three-dimensional instead of flat. It's one of the first techniques most builders pick up after learning nub cleanup, and it makes a bigger visual difference than anything else you can do without paint.

The good news: you can learn this in about five minutes. The slightly less good news: some panel lining products contain solvents that can damage plastic if you're not aware of the risks.

Why Your Build Looks Flatter Than the Sample Photos

Every Gunpla manual includes photos of a fully built sample kit, and those builds always look sharper than what you end up with from a straight build of the same parts. The reason isn't better lighting or photo editing - it's that the sample build has been panel lined. The grooves are filled in, the shadows are visible, and the shapes read as three-dimensional surfaces instead of flat plastic. Panel lining is what closes that gap.

Four Ways to Panel Line (And Which One Is Right for You)

There are four main panel lining methods, and each one has a specific use case. Here's what actually matters when choosing between them.

Gundam Markers (Fine Tip and Pour Type)

This is where most beginners start, and for good reason. Gundam Markers are pens made by GSI Creos specifically for panel lining Gunpla. The fine-tip markers (GM01 black, GM02 gray, GM03 brown) work by tracing directly along the groove. The pour-type markers (GM301P black, GM302P gray) work differently - you touch the tip to the groove and the ink flows through it via capillary action, similar to how the Tamiya panel liner works.

For cleanup, GSI Creos makes the GM300 Gundam Marker Eraser Pen, which is a solvent-filled pen designed specifically to dissolve and remove Gundam Marker ink. It's the proper cleanup tool for these markers. A cotton swab dampened with 91% isopropyl alcohol also works well for removing excess or correcting mistakes.

Best for: Beginners, unpainted kits, and quick builds where you want results fast.

Watch out for: The fine-tip markers can clog if you use them on dusty surfaces. A typical beginner mistake is pressing too hard when tracing - this damages the tip and makes the line worse, not better. If the marker isn't laying down enough ink, more pressure is not the answer. Shake it for a few seconds to get the ink moving, and if that doesn't work, the marker is just dried out and it's time to grab a new one. The fine-tip markers also don't flow into lines the way a liquid panel liner does, so you're doing more manual tracing with these.

Tamiya Panel Line Accent Color

This is the most popular panel liner in the hobby. It's a pre-thinned enamel-based liquid that comes in a small bottle with a brush built into the cap. You touch the brush tip to a panel line, and capillary action pulls the liquid through the entire groove on its own. Watching it flow for the first time is genuinely satisfying.

Tamiya Panel Line Accent comes in more colors than most people realize. Beyond the standard black, gray, and dark brown, there's also light gray, dark gray, and others that Tamiya has expanded the line with over the years. You clean up the excess with a compatible solvent and a cotton swab.

Best for: Anyone who wants clean, consistent results with minimal effort. Works beautifully on both painted and unpainted kits, especially over a gloss coat where the panel liner flows perfectly.

Watch out for: This is enamel-based. The solvent can damage certain plastics if handled incorrectly or used in excess. We'll cover how to prevent that below, because this is the most common question in the entire hobby.

Acrylic Panel Liner (The Newer Option)

There's now an acrylic alternative to the enamel approach. Stedi makes an acrylic panel liner that works on the same principle as Tamiya's - bottle with brush applicator, touch it to a panel line, capillary action does the rest - but it's water-based instead of enamel-based. The big advantage is that it won't damage your plastic, and cleanup is significantly easier.

The trade-off is durability. Acrylic panel liner isn't as resilient as enamel once it's dry. It can rub off more easily during handling, and it doesn't grip the surface as aggressively. For kits that are going straight to a display shelf and getting sealed with a top coat, this isn't really an issue. For anything you'll be handling a lot or repositioning frequently, the enamel option holds up better.

Best for: Builders who want the capillary-flow convenience of Tamiya Panel Line Accent without the risk to plastic. Also a good option if you're working in a space where strong solvent fumes are a problem.

Watch out for: Less durable than enamel. Make sure to seal with a top coat to lock it in.

DIY Panel Lining

If you already have paints on your shelf, you can mix your own panel liner. This isn't a new idea - military scale modelers have been mixing their own washes for decades using the same basic approach. The technique is slightly different (washes cover broader surfaces for weathering effects, panel lining targets specific grooves), but the chemistry is the same.

The enamel route is straightforward: thin enamel paint (Tamiya or Mr. Color enamel) to a very watery consistency until it flows the same way Tamiya Panel Line Accent does.

There's also a DIY acrylic method that's been around in the scale model community for a long time: thinning acrylic paint with water and a tiny amount of dish soap. The dish soap acts as a surfactant - it reduces the surface tension so the thinned acrylic flows into panel lines instead of beading up on the plastic. Some builders use diluted rubbing alcohol instead of water for faster evaporation, but the ratios vary and it's worth experimenting on a spare part before committing to a kit.

Best for: Experienced builders who want precise color control or who already have paints in their workflow.

Watch out for: Getting the consistency right takes practice either way. Too thick and it won't flow. Too thin and it won't show up.

What Color Should You Use?

The general rule comes down to matching the panel line color to the surface it's going on:

Gray on white and light-colored parts. This is the most realistic option for most kits. Gray creates a subtle shadow effect that looks like natural depth rather than someone drawing on the model with a Sharpie. That said, some builders prefer black even on white parts, especially on larger kits where panel lines are spaced far apart and need the extra contrast to be visible at normal viewing distance.

Brown on red, yellow, orange, and warm-colored parts. Brown blends naturally with warm tones and avoids that harsh, outlined look.

Black on dark blue, dark green, dark gray, and other deep-colored parts. Black on dark parts creates enough contrast to be visible without looking unnatural.

That said, plenty of builders just use black on everything. It gives the kit a sharper, more anime-accurate look with stronger contrast. It's technically less realistic but looks great on shelf, especially on HG kits where the scale is small enough that subtlety gets lost anyway. Neither approach is wrong. Try both and see what you prefer.

One more note: you generally don't panel line black parts. There's no darker color that shows up well without looking weird. (Darker than black? If you figure that one out, let us know.)

The Correct Workflow (This Matters)

Where panel lining fits in your build process depends on whether you're painting your kit. But either way, there's a specific order that protects your work and produces the best results.

The correct sequence is:

Build → Paint (optional) → Gloss coat → Panel line → Apply decals → Final top coat

The gloss coat before panel lining serves two critical purposes. First, it creates a smooth surface that lets the panel liner flow through lines cleanly. Enamel panel liner on bare, slightly rough plastic tends to stain the surface and become much harder to clean up. On a glossy surface, the excess wipes away cleanly. Second, the gloss coat acts as a protective barrier between the plastic (or paint) and the enamel solvent.

If you're doing a quick straight build with no paint, you can panel line on bare plastic with Gundam Markers and it'll work fine. But if you're using Tamiya Panel Line Accent or any enamel panel liner, a gloss coat first is strongly recommended. This is also where the acrylic option shines - if you're panel lining bare plastic without a gloss coat, acrylic panel liner removes the solvent risk entirely. Our top coat guide covers everything you need to know about choosing and applying one.

After your panel lines are dry and your decals are applied, the final top coat (matte, semi-gloss, or gloss - your call) seals everything together and gives the kit its finished appearance.

When Panel Lining Goes Wrong

Search Reddit for "Tamiya panel liner cracked" and you'll find plenty of threads with titles like "First time tried Tamiya panel line and it already cracked" and "Tamiya panel liner takes another victim." The most common failures - cracking, caking, paint lifting during cleanup - trace back to the same chemistry: the solvent in enamel-based panel liner is aggressive on bare polystyrene and ABS, and the damage gets dramatically worse on parts already under physical stress.

A few things that reduce the risk:

• Apply a gloss coat first. Creates a barrier between the enamel solvent and the bare plastic. It won't make the part invincible, but it reduces the chemical risk and makes cleanup easier. Our top coat guide covers how to apply one properly.
• Don't force it. If the panel liner won't flow into the line, the surface is too rough or the line is too shallow. Adding more product is exactly how pooling starts, and pooling is what leads to cracking.
• Consider an acrylic alternative. Acrylic panel liners like Stedi avoid the solvent issue entirely. The trade-off is durability, but it's worth considering for a kit you've put hours into.
• Let it dry completely. Give it at least a couple of hours before handling parts aggressively.

For cleanup, Gundam Markers can be removed with the GSI Creos GM300 Eraser Pen (purpose-built for this) or a cotton swab dampened with 91% isopropyl alcohol. Tamiya Panel Line Accent and enamel panel liners need a compatible solvent. From gentlest to most aggressive: Mr. Hobby Weathering Color Solvent (T110), Zippo lighter fluid (naphtha), Tamiya X-20 Enamel Thinner, and general hobby enamel thinners. Availability runs in the opposite direction - T110 is the hardest to source, lighter fluid is at any convenience store, X-20 is somewhere in between, and generic enamel thinner is everywhere. Use the gentlest one you can get your hands on.

The technique is the same regardless of solvent: lightly dampen a cotton swab (dampen, not soak), wipe in one direction, and replace the swab frequently so you're not pushing dirty solvent around the part.

Where Panel Lining Fits in Your Gunpla Journey

If you haven't dealt with nub marks yet, start there. Panel lining draws attention to your kit's surfaces, and it's hard to appreciate cleanly inked panel lines when the parts they're on still have white nub scars next to them.

After panel lining, the natural next steps are applying decals and top coating. Nubs, panel lines, and a top coat together will get any straight build looking dramatically sharper than it does fresh off the runners - no airbrush, paint booth, or years of experience required.

If you're still figuring out which kit to practice on, our Gunpla grades guide can help you find something at the right level. High Grade kits are ideal for practicing panel lining - enough detail to make the result visible, cheap enough that you won't stress about mistakes.