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How to Panel Line Gunpla (and Which Panel Liner to Use)

How to panel line a Gunpla kit with a Gundam Marker or a wash, which panel liner suits your kit's plastic, and how to clean up mistakes.

By Gundam Models editorial teamUpdated October 5, 20263 min readHow we research

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A white and red Unicorn Gundam model with a golden horn, seen close up

To panel line Gunpla, run a fine Gundam Marker or a thin panel line wash along the recessed lines on each part, then wipe away anything outside the line. A gray or black line makes the molded detail stand out. Start with a marker: Bandai points beginners to Gundam Markers for inking, and they need no brush or thinner.

Wikipedia describes panel lining as applying paint or ink with a fine-tipped brush or pen to the grooves where the kit’s panels meet, so the lines “pop”. Airfix lists panel line wash among the tools that add realism once you have the basics.

Choose your panel liner

A built Gundam Barbatos model holding a long sword on a white background — Thin dark lines in the recesses make molded detail readable at a distance.

Panel liner	How it works	Good for
Fine-tip Gundam Marker	Draw along the line	First kits, quick results
Pouring inking pen	Touch the tip to the line; ink flows along it	Deep, clean recesses
Panel line wash	Brush a thin liquid into the line; wipe off excess	Larger kits, softer lines

Mr. Hobby’s Gundam Marker range includes a pouring inking pen set, the Gundam Marker Liner Sharp and Fine Edge sets, all listed on its product page.

Safety

Check your plastic before you use a wash. Bandai warns that alcohol-based Gundam Markers must not be used on parts whose runner is marked “ABS”, that enamel paints and enamel thinner can damage parts, and that lacquer and alcohol solvents can damage ABS. Wikipedia notes that Gunpla is mostly polystyrene with some ABS parts, so check the runner markings. Ventilate the room and let markers dry fully.

How to panel line with a marker

Wash and dry the parts if they are dusty, so ink sits only in the line.
Hold the marker at a low angle and draw along the recessed line in one smooth pass.
Wipe the excess from the flat surface with a cotton swab or a soft eraser before it sets.
Work one part at a time, while it is still off the kit and easy to hold.
Let it dry completely before handling or spraying a top coat.

How to use a panel line wash

Load a fine brush and touch it to the line; the wash runs along the groove.
Use very little. A drop goes a long way.
Let it dry, then clean the surface with a cotton swab.
Keep it off joints and stressed parts, following Bandai’s warning about enamel products.

Panel line markers and washes

Shop panel line markers and washes

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Gray, black or brown?

Pick by the part color. Black lines give strong contrast on white and light gray parts. On dark parts, a gray or lighter line keeps detail visible without looking harsh, and on red or yellow armor a brown line reads softer. There is no rule: try a line on a hidden part first.

Common panel lining problems

Ink spreads beyond the line. The marker tip is too wide or the line too shallow. Use a finer tip or a pouring pen.
Lines smear under the top coat. Let the ink dry fully first, then spray light coats and let each one dry.
A part cracked after a wash. The solvent reached stressed plastic. Use less wash and keep it away from joints.

Which lines to panel line

You do not need to line every recess. Start with the lines that show most: the face and head, the chest and the large flat armor panels on the legs and shield. Leave deep vents and gaps between separate parts for last; they often look dark already. On a small 1/144 kit, a few well-chosen lines look cleaner than lining every groove.

What to do after panel lining

After lining, apply water slide decals and seal everything with a top coat. The Gundam Marker guide explains the other marker types, and the build guide covers the whole process.

Frequently asked questions

What is the best panel liner for beginners?

A fine-tip Gundam Marker. Bandai's beginner guide points to Gundam Markers for inking, and a marker needs no thinner or brush. Mr. Hobby also sells a Gundam Marker pouring inking pen that flows into the lines.

Can panel line wash crack Gunpla?

It can. Bandai warns that enamel paints and enamel thinner can damage parts, and that lacquer and alcohol-based solvents can damage ABS. Use a small amount, keep it in the lines, and avoid joints and parts from runners marked ABS.

How do I fix a panel line mistake?

Wipe the excess before it sets, with a cotton swab or a soft eraser for marker ink. Airfix lists cotton swabs and toothpicks for detail work and corrections.

Should I panel line before or after assembly?

Many builders line parts before assembly, while they are easy to hold, and touch up after. Either works for marker lining; for a wash, keep the liquid away from joints and parts you will stress when assembling.