How to Thin Contacta Professional Glue for Precision Work
By Modellbau & Plastikmodellbau | Published: 2026-10-17
Category: How-to Guides
Learn how to thin Contacta Professional glue for precise model assembly. Step-by-step guide with tips on application and common mistakes to avoid.
Quick answer
To thin Contacta Professional Extra Thin glue, add a few drops of liquid cement thinner or acetone until it reaches a water-like consistency. Apply with a fine brush or needle applicator for capillary action into tight joints. Avoid over-thinning, which can weaken the bond.
Why Thin Contacta Professional Glue?
Contacta Professional Extra Thin glue is already formulated for precision, but some modelers prefer an even thinner consistency for specific tasks like attaching photo-etched parts or filling hairline seams. Thinning improves capillary action, allowing the glue to seep into microscopic gaps without leaving excess residue.
However, thinning reduces the adhesive's solvent concentration, which can slow bonding time. For most plastic model assembly, the stock consistency works well. Reserve thinning for situations where absolute minimal glue visibility is critical.
Choosing the Right Thinner
Use a solvent compatible with polystyrene plastic, such as Tamiya Extra Thin Cement or pure acetone. Avoid water-based thinners or alcohol, as they don't dissolve the plastic and will ruin the glue's effectiveness. Always test on a scrap sprue first to ensure the mixture still melts plastic properly.
Step-by-step guide to thinning Contacta Professional glue
- Prepare your workspace: Work in a well-ventilated area and protect your surface with a silicone mat or paper towel. Have a small glass or metal container ready for mixing. Checkpoint: Ensure no open flames nearby, as solvents are flammable.
- Add glue to the mixing container: Squeeze a small amount of Contacta Professional Extra Thin glue into the container. Start with about 10 drops — you can always add more. Common mistake: Using too much glue at once makes it hard to control the thinning ratio.
- Introduce thinner drop by drop: Using a dropper or toothpick, add one drop of thinner (e.g., Tamiya Extra Thin Cement or acetone) to the glue. Stir gently with a clean toothpick. Repeat until the mixture flows like water off the toothpick. Checkpoint: Stop when the mixture runs off the toothpick in a steady stream, not a glob.
- Test on a scrap sprue: Apply a small amount of thinned glue to a leftover plastic sprue. It should wick into the gap quickly and soften the plastic within 5 seconds. If it beads up, it's too thick; if it evaporates instantly, it's too thin. Common mistake: Skipping the test can lead to ruined parts if the glue is too aggressive.
- Apply with precision: Use a fine brush or a needle applicator to place the thinned glue exactly where needed. Touch the applicator to the joint edge — capillary action will draw the glue in. Hold parts together for 10-15 seconds. Checkpoint: Wipe any excess immediately with a lint-free cloth to avoid marring the plastic surface.
Product fact
- Contacta Professional Extra Thin Glue - 30ml: Contacta Professional Extra Thin – precision and speed for model making. This high-precision adhesive is particularly thin and is ideal for delicate gluing work. Thanks to the extra fine consistency, the adhesive penetrates into the smallest gaps and connects parts seamlessly. Because it's already thin, you only need minimal thinning to achieve capillary action. Over-thinning can make it runny and hard to control.
