Seal, color, and gloss: primer sealer, base coat, and 2K clear

Most people picture this stage as the fun part, finally putting color on. In practice it’s mostly mixing and spray control — the color is the easy bit.

This stage picks up at a paint-ready surface — uniform matte primer, no guide coat left, no exposed plastic. If your part isn’t there yet, go back to Stage 03: Smoothing. From here the part gets three products in order: a black primer sealer, a base coat of Toyota Obsidian Black, and a 2K clear. What you want out of this stage is a deep, even gloss black that stands on its own as painted armor — and, if you’re heading for chrome later in the series, that same gloss black is the surface the chrome needs.

The foundation of this process is CTProps’ finishing tutorial, adapted to my booth, my guns, and the products I can get locally.

Safety comes first here

Is this guide for you?

Start this stage if your part is smoothed and primed with no guide coat left and no exposed plastic, you have a ventilated spray area and the right PPE, and you’re willing to practice on scrap before you touch a hero piece.

Hold off if you can still see print lines, low spots, scratches, or bare plastic; if the part has dust, grease, or fingerprints on it; if you don’t have a ventilation plan and the correct PPE; or if you haven’t tested your spray pattern on scrap yet. Fixing those first is cheaper than sanding a bad paint job back off.

How the paint system works

By the time you’re here the part is smoothed, primed, guide-coated, and sanded, so the surface is uniform matte primer. The layers go on in this order, bottom to top:

1. Filler primer fills and removes the print lines back in Stage 03.
2. Primer sealer seals the porous primer and brings the part close to black.
3. Base coat is the final black color.
4. 2K clear is the gloss, depth, and durability.

The sealer matters because primer drinks paint. Spray base straight over primer and you burn more base getting to full color, and the finish can come out blotchy. The sealer gives the base a consistent surface to land on. And the base itself isn’t supposed to be shiny — base dries matte or satin. The gloss is the clear’s job, three coats from now.

Beginner terms

Flash. The time between coats when solvent evaporates out of the paint. The surface goes from wet-looking to dull or tacky.

Pot life. How long a mixed 2K product stays usable before it thickens or cures in the cup.

Wet edge. The still-receptive edge of the last pass. The next pass should overlap it while it can still blend in.

Dry spray. Paint that partly dries before it lands, leaving a rough, dusty texture.

Solvent pop. Tiny pinholes from spraying too much material too fast, so trapped solvent escapes through the surface.

Orange peel. A bumpy, orange-skin texture from dry spray, poor atomization, or uneven material.

Recoat window. The time range where another coat bonds properly. Check the product tech sheet for the exact window.

Tools & Materials

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Get the Parts Into the Booth

Parts come into this stage still mounted on their work holders from Stage 03, and they stay mounted through sealer, base, and clear. Dust is the main problem in the booth — every speck that lands in wet paint becomes a nib you’ll be sanding out later.

1. Wipe down every surface. Surface dust, grease from fingers, anything the part picked up in the workspace. Hit all the edges, nooks, and crannies — every surface that’s going to get paint gets wiped.
2. Stage the parts in front of the booth filters. Keep the work pieces in front of the vents so the airflow pulls overspray and floating dust away from the parts instead of letting it settle on them.
3. Air and tack cloth right before you spray. Blow the dust toward the exhaust fan, then run the tack cloth lightly over the surface — you’re picking up dust, not scrubbing.

Mix by Ratio, in Small Batches

These are two-component products measured by volume. The graduated mixing cups make it repeatable: for a 4:1:1 mix you fill product to a number in the 4 column, hardener to the same number in the 1 column, and reducer to the same number in the last column. Always follow the product tech sheet first — reducer adjusts sprayability, it does not replace hardener when a product needs it.

Different gun, nozzle, reducer, hardener, temperature, or product line? Confirm the mix on the tech sheet and test on scrap.

1. Gloves on, then open the cans. Don’t handle hardener or mixed 2K barehanded. Check the hardener lip for crust before you pour — that crust is where particulates come from.
2. Measure with the cup columns or a syringe. The cup columns handle normal batches; a syringe is more accurate for small ones — 20 units of paint, then 5 and 5 of hardener and reducer gets you the same 4:1:1.
3. Keep the batches small. A mixed 2K batch stays sprayable for a limited time, and a fresh batch sprays noticeably better than one near the end of its pot life. The lesson I learned the hard way: mix small, use it up, mix fresh.
4. Stir until the air bubbles move freely. Scrape the sides and bottom of the cup as you go. If the bubbles aren’t moving, it’s not mixed.
5. Strain it into the gun cup. The filter catches hardener crust and anything that started drying in the cup.

Coat 1: Primer Sealer

Primer will soak up base coat. The sealer is the barrier that stops that — and because it’s black, it brings the part close to final color before the base ever goes on, so you use less base to get to the shade you want. I use Sherwin-Williams Dimension DS694, a 2K acrylic urethane.

1. Mix per the ratio table and product sheet. Airbrush for small parts, HVLP for helmets and plates.
2. Spray for coverage, not gloss. This coat doesn’t need to be a shiny wet coat — it just needs to get the whole part black. Light passes, keep the gun moving, and press the trigger only while you’re over the part.
3. Chase the dry spots. Inside edges and recesses hold dry spots on the first pass. Go back over them with another light pass within a short window and it melts into the surrounding coat.
4. Let it flash before the base coat. Flash means the solvents have evaporated — the surface goes evenly dull and is dry to the touch. Use the product’s flash guidance.

What to expect: sealed parts look flat, almost satin. That’s correct — the gloss is the clear’s job, three coats from now.

Coat 2: Base Black

I asked Sherwin-Williams for their deepest black and they recommended Toyota Obsidian Black, so that’s what I shoot. The base is cut thin — about one part paint to two parts reducer — which is why the technique below is all dusting and layering. Thin material floods and runs if you try to lay it on heavy.

1. Start with a dusting, not coverage. The first pass lays an initial layer that the next coats stick to and blend into. It will look dull and patchy. Leave it.
2. Build in light coats, minutes apart. Give each layer a moment to flash, then the next pass melts right into it. Once there’s an initial tacky layer down, the coats can get a little heavier.
3. Use air to help it flash. Gentle airflow from a distance speeds the solvent off between passes. Not too close — close air pushes the wet paint around and ripples the surface.
4. Check the edges for dry spots. Same habit as the sealer: dry spots show up around edges first. Another light coat within the melt-in window fixes them; wait too long and you’re starting a new layer.
5. Stop at even coverage. Base dries to a matte finish. Don’t chase gloss here — more base just risks pooling in the details.

What to expect: the part looks like matte black plastic when the base is done. If you can see even color from every angle with no thin patches showing sealer through it, you’re ready for clear.

Coat 3: 2K Clear

The clear carries the gloss and the durability. Two-component clear cures chemically — hard and resistant to the cleaners and handling that wearable armor sees. I’m currently spraying Finish One FC-710, their spot clear, which flashes faster than an overall clear. I run the medium hardener because my sessions run long and I don’t want the batch going gummy in the cup.

1. Flush the gun first. Clear shows everything, including whatever was left in the gun from the base coat. Break it down, run thinner through it, and check the air passages.
2. Mix 4:1:1 and strain it. Same cup, same columns. Clear has no pigment to settle, but the hardener crust still ends up in the cup if you skip the filter.
3. Lay a tack coat. The first pass is not meant to be a full wet coat — it’s a sticking coat. Dust it on and let it go dull.
4. Dust, dry, dust, then go wet. Dust it, air it off, dust it again, air it off — and then move into a controlled wet coat. By that point the surface accepts paint and each pass melts straight in.
5. Keep the coats melting together. Don’t wait ten or fifteen minutes between passes — you want the next coat to melt into the last one while it’s still receptive. Wait too long and you’re into the recoat window, which is a different layer altogether. Check your product’s tech sheet for that window.
6. Read the reflections as you go. Keep a light on the part and watch the reflection: you can see each pass melt in, and you can see it going on too heavy. Two to three coats total, built this way, gives you gloss straight from the gun.

What to expect: the first pass looks bumpy and dry. Each layer after that goes on slicker and glossier until it starts looking like glass. That’s the process working — don’t try to shortcut it with one heavy coat.

Spray Technique

The three coats above are what to spray. This is how I spray them — it’s all prep and calibration: equipment, environment, spray pattern, distance, speed, fluid flow.

Common Mistakes

• Runs. Too much material at once — gravity pulls it down and it sags. Let it cure, wet sand at 800 to flatten, then re-base and clear again. Scuff the whole panel while you’re there, not just the run: I’ve chased a single run with a small patch of sanding and ended up cutting through the base into the sealer, which shows as a different shade of black. One even scuff avoids that.
• Dry edges. Honestly worse than a run. A run you can sand flat and re-coat locally; a dry edge means sanding the whole surface and re-clearing. If a pass lands dry, go straight back over it with another light pass and pick up a wet edge while it can still melt in.
• Solvent pop. Little pinholes that appear when there’s too much material down and the solvent has to escape through it. I still get solvent pop when I’m impatient. Lighter coats, more flash time, and airflow between passes.
• Orange peel — two kinds. Dry orange peel comes from spraying too far away, moving too fast, or running too much pressure: the droplets dry in the air and land without enough material to level out. Sag ripple comes from the opposite — plenty of material, but the gun too close, and the air itself pushes the wet surface around. Fix the first with distance, speed, and pressure; fix the second by backing off.
• Fish eyes from water in the line. I skipped draining my compressor tank once and the gun spat water all over a freshly cleared part — splatter, fish eyes, and a drip, all on one piece. Drain the tank and check the water separator before every session.
• Spraying a batch past its pot life. When the mix starts going thick it lays down gunky and uneven, and it’s easy to blame your technique instead of the cup. If it feels thick, strings off the stir stick, or sprays grainy, mix a fresh small batch — the difference is night and day.

Checkpoint: Cleared and Glossy

Let the clear cure fully before you sand or polish it — check the product tech sheet for the cure time.

FAQ

Can I do this with rattle cans?

Yes, but it’s a different paint system. Rattle cans can work for entry-level costume armor, especially while you’re still learning — they’re easier to get and don’t need a compressor or gun. The tradeoff is they’re harder to control, easier to overload, and usually less durable than this automotive process. If you go that route, stay inside one compatible product line, practice on scrap, and follow the can’s recoat windows. I use a compressor, gun, and 2K products because the results are more consistent and hold up better.

Can I skip the sealer and base over the primer?

I don’t recommend it. Primer soaks up base coat, so you end up spraying a lot more base to get to color, and it can look uneven. The sealer is the barrier, and since it’s already black, it does half the base coat’s job for it.

Can I use a 1K aerosol clear instead of 2K?

You can, but it won’t be the same finish. I use 2K because it cures into a hard, chemically resistant shell — which is what armor that gets handled, packed, worn, and cleaned needs. If you use a 1K clear, treat it as a different product system and test it over your base coat before it touches armor.

Airbrush or HVLP gun?

Both, split by part size. The HVLP (Iwata LPH-50, 0.6 mm fan nozzle) covers helmets, chest pieces, and large plates. The airbrush (Iwata Eclipse, 0.5 mm) handles darts, keypad inserts, and small gauntlet components with less overspray and a lot less wasted paint.

How long do I wait between coats?

Minutes, not hours — you’re waiting for flash, not cure. Flash means the solvents have evaporated and the surface has gone dull. The exact time depends on the product, temperature, humidity, reducer, and airflow. The next pass should melt into the last one; if you’ve waited long enough that it doesn’t, you’re into the recoat window and effectively starting a new layer. Check your product’s tech sheet.

Does the clear have to be perfect off the gun?

No. Full coverage with no runs or dry edges matters; a bit of orange peel doesn’t, because the optional mirror-polish step flattens it with 1200 grit on the way to the mirror. A dry edge is the one defect that forces a full re-clear, so keep your wet edge and build the gloss gradually.

Where you are in the series: this is Stage 04 of the Armor Finishing series. It picks up from Stage 03: Smoothing — primer, guide coat & block sanding and hands off to Stage 05: Chrome — with the optional Mirror Polish step in between if you want the deepest metal. Keep the part mounted on its work holder and let the clear cure fully before you sand it — check your tech sheet for the cure time.