Sprue Goo is a versatile modeling adhesive/filler made by dissolving plastic sprues in liquid cement. It’s especially useful for filling seams, gaps, and weld lines in scale models because it bonds chemically with the plastic.
What You’ll Need
- Plastic sprue (leftover runners from your model kits – ideally same type of plastic)
- Liquid plastic cement (e.g., Tamiya Extra Thin, Testors Liquid Cement)
- Glass bottle with a tight lid (an old cement jar works perfectly)
- Hobby knife or sprue cutters
- Optional: stirring stick/toothpick
Safety First
- Work in a well-ventilated area
- Avoid skin contact and inhaling fumes
- Keep away from heat or flames
- Always seal the container tightly when not in use
Step-by-Step Instructions
Step 1: Prepare the Sprue
- Take leftover sprue and cut it into small pieces (2–5 mm chunks).
- Smaller pieces dissolve faster and create a smoother mixture.
Step 2: Fill Your Container
- Place the sprue pieces into your glass jar.
- Fill it about 1/3 to 1/2 full—don’t pack it too tightly.
Step 3: Add Liquid Cement
- Pour liquid cement into the jar until the sprue is fully submerged.
- Leave a little space at the top for mixing.
Step 4: Let It Dissolve
- Close the lid tightly and let it sit for 6–24 hours.
- Stir occasionally to help break down the plastic.
- You’ll see it turn into a thick, melted-plastic slurry.
Step 5: Adjust the Consistency
You can tailor Sprue Goo depending on your needs:
Thicker (gap-filling putty):
- Add more sprue pieces
- Let it sit longer
Thinner (brushable glue):
- Add more liquid cement
Ideal consistency is like thick paint or syrup.
Step 6: Test Before Use
- Try it on a scrap piece of plastic.
- Check:
- Flow
- Drying time
- Strength
Adjust if necessary.
How to Use Sprue Goo
- Gap Filling: Apply along seams; let dry, then sand smooth
- Strengthening Joints: Apply inside seams for reinforcement
- Surface Repairs: Great for fixing sink marks and small imperfections
- Weld Beads (AFV modeling): Dab and texture with a hobby tool
Drying Time
- Surface dry: 30–60 minutes
- Fully cured: 12–24 hours (longer for thick applications)
Always allow full curing before sanding.
Pro Tips from AFV Hobby Hub
- Use matching sprue (same kit) to ensure identical plastic properties
- Label your jar (different brands of plastic may behave differently)
- Store tightly sealed to prevent drying out
- If it thickens over time, just add more cement and stir
Maintenance
Your sprue goo can last indefinitely:
- Refill with sprue scraps as needed
- Add cement to maintain ideal consistency
- Stir occasionally before use
Summary
Sprue Goo is an inexpensive, highly effective solution for modelers who want seamless finishes and strong bonds using the same plastic as their kit. With a little preparation and adjustment, it becomes an essential tool for any AFV hobbyist.
Leave your comment