How to Panel Line Gunpla: Gundam Marker vs Panel Liner

Quick answer

For beginners, a fine-tip Gundam Marker is the easiest way to panel line Gunpla: draw into the groove, let it set for a few seconds, then wipe the excess with a dry cotton swab. If you want faster coverage on large kits or tighter lines, use a pour-type panel liner and let capillary action fill the groove before cleaning up. Both methods work well; pick based on your kit size and comfort with cleanup.

Why panel lining makes your Gunpla look sharper

Panel lines are the dark grooves molded into Gunpla parts that represent separate armor plates. Out of the box, they are the same color as the plastic, so they disappear under bright light. Adding a dark line inside those grooves creates contrast and makes the kit look more detailed without any painting. It is the single fastest visual upgrade you can make.

The two main approaches are Gundam Markers and pour-type panel liner. Markers give you direct control and are easy to correct. Pour-type liner flows into grooves by capillary action, which is faster on complex surfaces but requires more careful cleanup. Many builders keep both on hand and switch depending on the kit.

Tools you actually need (and what you can skip)

You do not need a full hobby station to start panel lining. The essentials are a fine-tip Gundam Marker in black or dark gray, a pour-type panel liner if you want the faster method, a pack of cotton swabs, and a small amount of isopropyl alcohol for tough cleanup. A part separator or toothpick helps remove excess liner from deep corners without scratching plastic.

Skip cheap cotton swabs that shed fibers; they leave lint in the grooves. Also skip paper towels for cleanup because they can dull the surrounding plastic. If you plan to topcoat later, note that some pour-type liners can bleed if you apply a solvent-based clear coat too heavily. Test on a spoon or a runner first.

Step-by-step: panel lining with a Gundam Marker

Work on a clean, dry kit. If you have already applied decals, panel line before decaling to avoid smearing the decal film. For bare plastic, no primer is needed. Shake the marker with the cap on to mix the pigment, then press the tip on a runner to start the flow.

• Draw the marker tip gently along the panel line. Let the tip do the work; do not press hard or you will pool ink outside the groove.
• Wait 5–10 seconds for the ink to set slightly. This makes cleanup easier and reduces the chance of smearing.
• Wipe across the line with a dry cotton swab. Use light pressure and a fresh swab for each pass. If ink remains outside the groove, dampen the swab with a tiny amount of isopropyl alcohol.
• Check your work under a desk lamp. If a line looks too light, wait for the area to dry completely, then apply a second pass.
• Common mistake: wiping too soon or too hard. That pulls ink out of the groove and leaves a gray smear. Let it set, then wipe once.

Step-by-step: panel lining with pour-type liner

Pour-type liner comes in a bottle with a fine brush applicator. It is thinner than marker ink, so it flows into grooves on its own. This is ideal for long, continuous panel lines and for kits with many small details. Work in a ventilated area because the liner has a solvent smell.

• Touch the brush to the start of a panel line. Capillary action will pull the liner along the groove. Do not drag the brush; let the line fill itself.
• For long lines, apply in short segments and let each segment flow before moving on. This prevents overflow at corners.
• Wait 10–15 minutes for the liner to fully dry. It should look matte, not wet.
• Clean excess with a dry cotton swab first. For stubborn residue, dampen a swab with isopropyl alcohol and wipe perpendicular to the line.
• Common mistake: applying too much liner at once. That floods the groove and stains the surrounding plastic. If you flood, immediately wipe with a dry swab and let the area dry before retrying.

Choosing between marker and pour-type liner

Use a Gundam Marker when you want precise control, when you are working on a small number of lines, or when you are panel lining a kit with shallow grooves. Markers are also better for curved surfaces because you can follow the shape with the tip. They are more forgiving for beginners.

Use pour-type liner when you need to cover many long panel lines quickly, or when the grooves are deep and well-defined. It gives a consistent, thin line that looks like a molded shadow. However, it requires more drying time and careful cleanup. If you are panel lining a Master Grade kit with lots of surface detail, pour-type liner can save hours.

A practical compromise: keep a fine-tip black Gundam Marker for touch-ups and a pour-type liner for the main pass. Many builders use pour-type for the body and marker for tight corners and small vents.

How to fix common panel lining problems

If your line looks uneven, the groove may be too shallow or you may have wiped too aggressively. Clean the area with isopropyl alcohol, let it dry, and reapply with a lighter touch. If the liner bleeds outside the groove, wipe immediately with a dry swab. Do not use alcohol on wet liner; it will spread the pigment.

If the line disappears after topcoating, you likely applied a hot solvent-based clear coat that re-wet the liner. Use a water-based topcoat or apply thin mist coats and let them dry between passes. Always test your topcoat over a lined runner before spraying the whole kit.

If you accidentally line over a decal, stop. Let the liner dry, then gently scrape the liner off the decal with a toothpick. Do not use alcohol on decals; it can damage the film.

Panel lining steps at a glance

1. Prepare the surface: Clean the part with a dry cloth and remove any sanding dust. If you sanded, use a GT08A Grinding Cloth Sheet on your GT08 tool to smooth the area. Checkpoint: the plastic should be free of oils and dust before you apply liner.
2. Choose your tool: For precise control, use a fine-tip Gundam Marker. For fast coverage on long lines, use a pour-type panel liner. Checkpoint: test on a runner to see how the ink or liner flows.
3. Apply the liner: For marker: draw along the groove with light pressure. For pour-type: touch the brush to the groove and let capillary action fill it. Checkpoint: avoid flooding. If you flood, wipe immediately with a dry swab.
4. Let it set: Wait 5–10 seconds for marker ink or 10–15 minutes for pour-type liner. The liner should look matte, not wet. Checkpoint: do not rush cleanup; wet liner smears.
5. Clean up: Wipe across the line with a dry cotton swab. For stubborn residue, dampen the swab with isopropyl alcohol. Checkpoint: use a fresh swab for each pass to avoid spreading pigment.
6. Apply decals and topcoat: After panel lining, add decals such as Gundam Decal 135 The Witch from Mercury Multiuse 3. Then apply a water-based topcoat in thin mist coats. Checkpoint: test topcoat on a lined runner first to ensure it does not bleed the liner.

Products that help with panel lining

• Gundam Decal 135 The Witch from Mercury Multiuse 3: Gundam Decal 135 The Witch from Mercury Multiuse 3 is an officially licensed BANDAI decal sheet with a variety of markings for customization, themed for The Witch from Mercury series. After panel lining, adding decals from this sheet can further enhance detail on your Gunpla. Apply decals after panel lining to avoid smearing the liner.
• GT08A Grinding Cloth Sheet for GT08: GT08A Grinding Cloth Sheet is a replacement accessory for the GT08 tool, made by Mr. Hobby, and provides a convenient surface for sanding and finishing tasks in modeling projects. If you need to sand a part before panel lining to remove mold lines, this cloth sheet keeps your GT08 tool working. Smooth plastic helps liner flow evenly.