Resin model kits are a popular choice for hobbyists who want high levels of detail and unique subjects not found in standard plastic kits. While they require a different set of skills and tools compared to traditional plastic modeling, the results can be incredibly rewarding. This guide will walk you through the basics of resin kits, safety requirements, and the step-by-step process of building your first model.
What Are Resin Model Kits?
Resin model kits are made from a liquid polyurethane resin that is poured into silicone molds. Unlike mass-produced plastic kits made of polystyrene, resin kits are often produced in smaller batches by specialized companies or individual artists. This allows for much finer detail and the production of niche subjects like historical figures, sci-fi prototypes, and custom car parts.
Because the production process is more manual, resin kits often come with unique characteristics. You may notice more surface texture, smaller parts, and different attachment points than you would see on a sprue in a plastic kit. Understanding these differences is the first step toward a successful build.
How Resin Differs from Plastic
Before you begin, it is important to understand that resin behaves differently than the plastic found in most hobby store kits. The most significant difference is how the pieces are joined together. Standard plastic cement works by melting the surfaces of the plastic to create a chemical bond; however, this does not work on resin.
Resin is also more brittle than styrene plastic. While it holds sharp details very well, it can snap or chip if handled roughly. Additionally, resin parts often have “flash” (excess material) and large “pouring gates” where the liquid resin entered the mold, which must be carefully removed before assembly.
Essential Safety Precautions
Safety is the most important factor when working with resin. When you sand or saw resin parts, they produce a very fine, powdery dust. This dust can be harmful if inhaled, so you must take specific precautions to protect your health.
- Wear a Mask: Always wear a high-quality dust mask or a respirator (such as an N95) when sanding or cutting resin.
- Wet Sanding: Whenever possible, sand your parts under a small stream of water or dip your sandpaper in water frequently. This keeps the dust from becoming airborne.
- Ventilation: Work in a well-ventilated area to ensure any stray particles or glue fumes dissipate quickly.
- Clean Up: Use a damp paper towel to wipe down your workspace after a session to trap any remaining dust.
Required Tools and Materials
To build a resin kit, you will need a few specialized items that differ from a standard modeling toolkit. Having these ready before you start will make the process much smoother.
- Cyanoacrylate (CA) Glue: Commonly known as super glue, this is the primary adhesive for resin. You may want both a “thin” version for tight fits and a “medium” or “thick” version for filling small gaps.
- Hobby Knife and Saw: A sharp X-Acto knife is essential, and a small razor saw is helpful for removing thick pouring gates.
- Sandpaper and Files: A variety of grits (from 320 to 1000) will help you smooth out surfaces and remove mold lines.
- Dish Soap and an Old Toothbrush: These are used to wash the parts before assembly.
- Primer: A high-quality hobby primer is necessary because paint does not stick to bare resin very well.
Step 1: Washing the Parts
During the manufacturing process, a “mold release agent” is sprayed into the silicone molds to help the resin parts pop out easily. If this oily residue is left on the model, your glue and paint will not stick. This is a common mistake for beginners.
Fill a bowl with warm water and a small amount of mild dish soap. Use an old toothbrush to gently scrub every surface of each resin part. Rinse them thoroughly with clean water and let them air dry completely before moving on to the next step.
Step 2: Removing Gates and Flash
Resin parts are attached to large chunks of resin called pouring gates. You will need to remove these using a hobby saw or side cutters. Be careful not to cut too close to the actual part, as the resin might chip. It is better to leave a small nub and sand it down gradually.
“Flash” is the thin, paper-like excess resin found along the edges where the two halves of the mold met. You can usually scrape this away gently with the back of your hobby knife or a medium-grit sanding stick. Remember to use the wet-sanding technique to keep dust under control.
Step 3: Fixing Warped Parts
Because resin can be sensitive to heat during the curing process, some long or thin parts may arrive slightly warped or bent. Fortunately, this is very easy to fix. Resin has a “memory,” and it becomes pliable when heated.
Dip the warped part into a bowl of hot (but not boiling) water for about 30 to 60 seconds. Once the part feels flexible, gently bend it back into the correct shape and hold it there while you run it under cold water. The cold water “sets” the resin in its new, corrected position.
Step 4: Assembly and Filling Gaps
Once your parts are clean and straight, you can begin assembly using super glue. Since super glue bonds almost instantly, it is a good idea to “dry fit” the pieces first to ensure they align correctly. If a part doesn’t fit perfectly, you may need to sand the mating surfaces.
Even with careful preparation, resin kits often have small gaps between parts. You can fill these gaps using specialized hobby putty or by applying a thick layer of super glue and sanding it smooth once dry. For very small holes (air bubbles), a tiny drop of super glue or a dab of surface primer usually does the trick.
Step 5: Priming and Painting
You should never skip the priming stage with a resin model. A good primer provides a “tooth” for the paint to grab onto. Without it, your paint may flake off or peel when you handle the model. Use a spray primer designed for plastic or metal for the best results.
Once the primer is dry, you can paint the model using acrylics, enamels, or oils, just as you would with a plastic kit. Because resin kits often have very fine details, thin your paints properly to avoid filling in the delicate textures of the sculpt.
Common Challenges to Watch For
Working with resin requires patience. One common issue is “pinholes,” which are tiny air bubbles trapped on the surface of the resin during casting. If you find these, fill them with a tiny bit of putty or thick primer before you start your final paint job.
Another challenge is the weight of the parts. Larger resin models can be quite heavy. In these cases, you may need to “pin” the joints. This involves drilling a small hole into both pieces and inserting a short length of brass wire to act as a structural support before gluing them together.
Conclusion
Building resin model kits is an excellent way to expand your hobby skills and create truly unique display pieces. While the material requires extra attention to safety and different assembly techniques, the level of detail achievable is often superior to standard plastic. By following these steps—washing, careful sanding, and proper priming—you can ensure a professional-looking finish on every project.
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