GL45 Decanting Cap for Spray Paints

Overview

This is a custom GL45 bottle cap designed for controlled decanting of spray-can paints (e.g., Tamiya TS, Mr. Color) into standard 100 mL borosilicate media bottles. It keeps the process neat, prevents pressure buildup, and makes it easy to store paint for airbrushing.

Features

• GL45 threads — Fits standard 100 mL borosilicate media bottles and other GL45 labware.
• Angled spray port — Sized for WD-40 style spray straws (~2.6–2.7 mm OD) or custom inserts such as this one by Green_Cucumber (which is what I used here). Guides paint smoothly into the bottle and reduces splashing.
• 2.5 mm vent hole — Allows propellant gases to escape safely during decanting, preventing dangerous pressure buildup.
• Simple print — No supports required, prints cleanly at 0.20 mm layer height.

Usage Instructions

1. Screw the cap onto a clean GL45 bottle.
2. Insert a spray-can straw (e.g., WD-40 style) into the angled port.
3. Spray into the port (continuous spray or short bursts both work). Paint flows into the bottle while propellant escapes through the vent.
4. After decanting, leave the bottle vented for 30–60 minutes to allow gases to dissipate.
5. Swap to a solid GL45 cap for storage once bubbling has stopped.

⚠️ Safety Notes

• Always decant in a well-ventilated area or spray booth. Some mist may escape through the vent.
• Never seal the bottle immediately after decanting — allow gases to off-gas fully.
• Not food safe. For hobby use only.
• PLA works for prototypes and testing, but PETG is recommended for solvent resistance and long-term durability.

Print Settings (tested)

• Layer Height: 0.20 mm
• Walls/Perimeters: 3+
• Infill: 15%
• Orientation: Upright (threads vertical)
• Supports: Not required
• Material: PLA tested; PETG recommended for final use

Attribution

• Cap base design is derived from a CC-BY licensed GL45 model by WillemBr
• Modifications include the angled spray port and vent hole for paint decanting.
• Special thanks to Green_Cucumber for allowing me to use their straw geometry for the design!