If you’ve been levelling up your Gunpla builds with panel lining, nub removal, and a proper top coat, it’s time to tackle the finishing touch that separates a good kit from a truly outstanding one — water slide decals. With Bandai’s new Gundam Decal No. 143 for Mobile Suit Gundam Hathaway landing in stores on April 25, 2026, there’s never been a better time to master this skill. In this guide, we’ll walk you through everything you need to know about gunpla water decal application, from tools and prep all the way to sealing and the common pitfalls to avoid.
What Are Gunpla Water Slide Decals?
Water slide decals (also called waterslide transfers) are thin film markings printed on a paper backing. When you soak them briefly in water, the film separates from the backing and slides directly onto your kit’s surface. Bandai produces official Gundam Decal sheets for their kits, while third-party brands like Da Lin and G-Rework offer detailed aftermarket options with extra markings, caution symbols, and technical text.
Compared to the dry-transfer stickers and foil stickers included in most kits, water decals look much more realistic once sealed — the edges become nearly invisible, giving you results that look like the markings were painted directly onto the plastic.
Tools You’ll Need for Gunpla Water Decal Application
Before you start soaking anything, gather these tools. Having everything ready makes the process smooth and stress-free:
- Sharp hobby scissors or a panel cutter — for cleanly trimming each decal from the sheet
- Small bowl of clean water — room temperature works best; avoid hot water as it can damage the film
- Tweezers — flat-tip or soft-grip tweezers let you handle decals without tearing them
- Cotton swabs and a soft cloth — for blotting excess water and pressing the decal flat
- Mr. Mark Setter (optional but recommended) — a decal adhesion solution that helps the decal bond more firmly to the surface
- Mr. Mark Softer (optional but very useful) — softens the decal film so it conforms to curved or panel-lined surfaces without wrinkling
- A gloss top coat — applied before decals, it creates a smooth surface and prevents silvering
Step-by-Step: How to Apply Water Slide Decals to Your Gunpla
Follow these steps carefully and you’ll get clean, professional results every time.
Step 1 — Apply a Gloss Top Coat First
This is the most important step many beginners skip. Spray a gloss top coat over the area where you’ll be applying decals. The gloss layer fills in the microscopic texture of the plastic surface, giving the decal film a perfectly smooth base to sit on. Without this, you’ll get silvering — a cloudy, white haze around each decal that looks terrible once it dries. Let the gloss coat fully cure for at least a few hours before proceeding.
Step 2 — Cut Out the Decal
Using sharp scissors or a hobby knife on a cutting mat, carefully cut around the decal you want to apply. Cut as close to the printed area as possible to minimise the clear film border. The less clear film you leave, the more invisible the decal will look once applied and sealed.
Step 3 — Soak in Water
Slide the cut decal into a small bowl of clean water. Bandai’s official decals usually need about 4–6 seconds, while thicker third-party decals may need up to 20–30 seconds. The decal is ready when it starts to slide freely on the backing paper — don’t leave it too long or the adhesive will weaken.
Step 4 — Position and Slide Into Place
Using tweezers, pick up the decal with its backing still attached, place it close to the target area on your kit, then gently slide the decal off the paper using a damp cotton swab or your fingertip. Work slowly — you have a brief window to reposition the decal before it sets. If you applied Mark Setter to the target area first, you’ll have slightly more time to adjust the placement.
Step 5 — Remove Excess Water and Bubbles
Once the decal is in position, blot away any excess water using a soft cotton swab or the corner of a clean cloth. Gently press from the centre outward to push out any air bubbles or water pockets. Do not wipe sideways across the decal — press and dab to avoid smearing or tearing the film while it’s still wet.
Step 6 — Use Mark Softer on Tricky Surfaces
If your decal needs to wrap around a curved surface, a panel line, or a raised detail, brush on a small amount of Mr. Mark Softer directly onto the decal film. Within a minute or two, the film will wrinkle slightly — this is completely normal! Don’t touch it. As it dries, the film will conform to the underlying surface contours. If needed, apply a second thin coat. Once fully dry, the decal will look like it was painted on.
Step 7 — Let It Dry Completely
Leave your model undisturbed for at least 1–2 hours after placing decals. Avoid touching the decal surfaces or exposing them to dust during this time. In Malaysia’s humid climate, drying can take a little longer, so if you’re in a rush, a gently air-conditioned room helps speed things up considerably.
Step 8 — Seal With a Final Top Coat
Once all your decals are fully dry, apply a final top coat to lock everything in. Use a matte top coat for a realistic flat finish, or a semi-gloss for a subtle sheen. This seals the decal edges, protects the film from peeling, and ties together your panel lining and weathering for a beautiful, unified finish.
Common Gunpla Water Decal Mistakes to Avoid
Even experienced builders run into these issues from time to time. Here’s what to watch out for:
- Skipping the gloss pre-coat — this is the number one cause of silvering. Always gloss coat first, no exceptions.
- Over-soaking — leaving a decal in water too long weakens the adhesive. Once it slides freely on the backing, it’s ready.
- Pressing too hard — thin decal film tears easily when wet. Use light, gentle dabbing motions at all times.
- Applying to a matte or textured surface — matte plastic traps air under the decal film and causes silvering. A gloss coat solves this completely.
- Rushing the drying time — decals that aren’t fully dry before top coating can wrinkle or bubble under the spray.
- Using too much Mark Softer at once — apply a thin coat, wait, then add more if needed. Flooding the decal can dissolve the film entirely.
Which Water Decals Should You Buy for Your Kit?
For most builders, Bandai’s official Gundam Decal sheets are the easiest starting point — they’re thin, easy to handle, and sized perfectly for the kits they’re designed for. If you want to go further, Da Lin water decals and G-Rework decals offer incredibly detailed aftermarket sets with dozens of extra markings for HG, RG, and MG scale kits.
Check out the full water decal collection at Gundam.my — we stock a wide range of Bandai Gundam Decal sheets and Da Lin aftermarket decals for popular kits across all scales. And if you’re building a Hathaway-series kit right now, keep an eye out for the brand-new Gundam Decal No. 143 (Mobile Suit Gundam Hathaway Multiuse ②) hitting shelves on April 25, 2026!