Gunpla Panel Lining: Markers vs Wash, Step by Step

Every Gunpla kit is molded with recessed panel lines, the thin grooves that suggest armor plating and mechanical detail. Out of the box those lines are the same color as the plastic around them, so from a few feet away they barely register. Panel lining means running a dark (or sometimes light) line of ink, paint, or pigment into those grooves so they catch shadow and actually read as detail.

It is separate from painting the kit. You can panel line a fully unpainted, snap-together build and it will look dramatically better for almost no extra effort. That is why it is usually the first "real" technique people learn after nippers and a hobby knife.

A Gundam Marker is a felt-tip pen filled with a fast-drying, low-odor ink, sold in colors matched to common Gunpla colors (gray, black, brown, and so on). You run the tip along a panel line, let it sit for a few seconds, then wipe the excess off the flat surface around the line with a cotton bud or tissue before it fully dries.

The appeal is that there is no mixing, no thinner, and very little risk to the plastic. The tradeoff is that the tip is fairly broad and can wear down or fray with pressure, so tight curves and small parts take a steadier hand than they look like they should. I keep a gray and a black marker on the bench at all times because between the two you can line the vast majority of any kit.

An enamel or oil wash is a thinned paint you apply with a fine brush, letting capillary action pull it into the panel line, then wipe away the overflow with a cotton bud dampened in enamel thinner (or a low-odor alternative like lighter fluid, which a lot of builders reach for because it is cheap and dries fast). Because the wash is thin and flows on its own, it tends to produce finer, more consistent lines than a marker tip can manage, especially on tight detail.

The real caveat is that enamel paint applied directly and repeatedly to bare, unprotected polystyrene can make the plastic brittle over time, particularly around stress points near ejector pin marks or thin clips. That risk goes up if you are heavy-handed or leave the wash to sit for a long time before wiping. It is manageable, but it is the one thing that makes enamel washing feel like a step up in commitment from a marker.

For markers, most builders panel line before applying a top coat, then seal everything with a flat or semi-gloss coat afterward. The top coat locks the line in place and evens out any sheen difference between the ink and the plastic.

For enamel or oil washes, I lay down a gloss coat first, before the wash goes on. A glossy surface does two things: it protects the bare plastic from the enamel so you are not risking stress cracks, and it lets the wash flow more smoothly into the panel lines instead of dragging on a rougher matte surface, which makes cleanup easier. Once the wash is applied and cleaned up, a final matte or semi-gloss top coat goes over the whole kit to unify the finish and seal the wash in for good.

With markers, cleanup is just a cotton bud, sometimes lightly dampened, wiped along the flat surface next to the line while the ink is still workable. Move too slowly and it dries hard enough that you will need a little rubbing alcohol on the bud to lift it.

With enamel washes, cleanup is enamel thinner (or lighter fluid) on a cotton bud, worked in the direction of the panel line rather than across it so you do not drag pigment out of the groove you just filled. Go slow near any edge with exposed bare plastic, and avoid soaking a spot for too long. If a line goes wrong on either method, it is almost never a disaster: worst case you strip that one panel back with thinner or alcohol and redo it, you are not starting the whole kit over.

If this is your first few kits, start with a Gundam Marker in gray or black. It is forgiving, there is no thinner smell to manage, and you will get a real improvement in how the kit looks without adding a new failure point to the build. Once you are comfortable and want finer lines on a Master Grade or a kit with a lot of intricate paneling, an enamel or oil wash over a gloss coat is the natural next step.