Complete Guide to Preparing Resin Models for Painting

Why Washing Your Resin Models Is Essential

The first and most crucial step—washing your models—is often overlooked by beginners. When resin models are manufactured, they're released from their molds using a special chemical coating called mold release agent. This slippery substance prevents the uncured resin from sticking to the mold, but it also prevents paint from adhering properly to your finished model.

Without removing this mold release agent, your primer and paint will bead up on the surface like water on wax paper. This leads to:

• Poor paint adhesion and coverage
• Chipping and peeling paint during handling
• An uneven, blotchy paint finish
• Wasted time repainting problem areas

Investing 15-20 minutes in washing prevents hours of frustration later.

The Proper Washing Method

Washing resin models is straightforward, requiring minimal supplies:

What You'll Need:

• Warm water (not hot)
• Mild dish soap
• Soft bristle brush or old toothbrush
• Clean towel or paper towels
• Shallow container or bowl

The Process:

1. Fill your container with warm (but not scalding) water and add a few drops of mild dish soap
2. Submerge your model completely in the soapy water
3. Gently scrub every surface with your soft brush, paying special attention to crevices, recesses, and detailed areas where mold release agent can hide
4. Rinse thoroughly under running water until all soap is removed
5. Dry completely with a clean towel and allow to air dry for 10-15 minutes

Removing Flash and Mold Lines

Resin casting inevitably produces small imperfections where mold halves meet. These "mold lines" and excess material called "flash" need removal before painting for a professional finish.

Tools for the Job:

• Sharp hobby knife (X-Acto style)
• Fine-grit files (120-220 grit)
• Sanding sticks or sanding sponges
• Safety glasses (resin dust can irritate eyes)

Technique:

1. Identify mold lines by running your finger along the model's edges
2. Use your hobby knife to carefully scrape away major flash—angle the blade shallow to avoid gouging
3. File the mold line using smooth, even strokes perpendicular to the line, then sand smooth
4. Work progressively from coarse to fine grits for the smoothest finish

Filling Gaps with Putty

Gaps between parts and small defects in the resin require filling before painting. Two excellent options are available:

Milliput

A two-part epoxy putty that cures to a hard, sandable finish. Available in various colors, Standard Yellow/Gray is most versatile. Knead the two parts together until uniform, press into gaps, and smooth with a wet tool. Hardens in approximately 1 hour.

Green Stuff

A putty sculpting compound popular among miniature enthusiasts. Similar application to Milliput, but slightly more flexible during sculpting. Excellent for larger gaps and creative repairs.

Application Tips:

• Use a small amount—you can always add more
• Smooth putty with a wet sculpting tool for clean edges
• Once hardened, sand to blend seamlessly with surrounding surfaces
• Work in a dust-free area while curing

Pinning for Strength

For models with delicate or separate parts, pinning provides mechanical strength to prevent breakage during painting and handling.

Basic Pinning Process:

1. Select appropriate pin size—typically 1/32" to 1/16" diameter brass rod
2. Drill holes in both the part and the body where they'll join, using a pin vise or hand drill
3. Insert the pin partially into one hole, then dry fit to mark the matching position
4. Glue with superglue or two-part epoxy for permanent joining

Dry Fitting Components

Before gluing anything permanently, dry fit all components together without adhesive. This crucial step reveals:

• Alignment and fit issues
• Gaps requiring gap-filling
• Parts that need further cleanup
• Assembly sequence problems

Dry fitting before committing to glue prevents irreversible mistakes and saves hours of correction attempts.

Priming Your Model

After all cleanup, filling, and assembly, priming creates an ideal surface for paint adhesion and color accuracy.

Why Prime?

• Provides a uniform base color
• Improves paint coverage and adherence
• Highlights remaining surface defects before painting
• Seals the resin surface

Priming Options:

Spray Primers: Fast and even coverage. Apply light coats from multiple angles in a well-ventilated area.

Brush-On Primers: Better for fine details and don't require ventilation. Takes longer but offers excellent control.

Color Selection: Black primer for darker paint schemes, white for bright colors, and gray for general work.

Common Mistakes to Avoid

• Skipping the wash: Mold release agent is invisible but devastating to paint adhesion
• Using too much putty: Excess filler requires extensive sanding and looks obvious
• Inadequate sanding: Rush through surface prep and you'll sand through primer during painting
• Not testing fit first: Gluing parts that don't align wastes time and material
• Applying thick primer coats: Heavy primer obscures fine details—use thin, multiple coats instead
• Skipping safety gear: Resin dust is cumulative and irritating—always protect yourself

Get Your Prep Supplies

Browse our complete selection of preparation tools and materials at our Accessories Collection. We stock quality files, putties, primers, brushes, and safety equipment for every preparation task.

Have questions about specific preparation steps? Check our Frequently Asked Questions for detailed answers to common preparation concerns.