The needle cap is used in technical aerosol painting for effects and detail work. This tutorial shows how to modify it into a custom skinny cap. If left unmodified it produces a strong flow of paint suitable for bursts of color as well as drip effects, basically a splatter cap. Experimentation with custom tips is the key to understanding how to atomize the paint in different ways.
miniature safety pin (smallest possible)
needle cap (either hooded or normal)
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Shape the Tip
1. Hold the cap at its edge furthest away from the straw. Don’t allow the cap to slip into the fire when smelting its edge.
2. Flick the bic lighter and hold the flame for a few seconds. Make sure you are not in a cold location because the metal guard on the lighter will not get hot enough.
3. Place the straw of the needle cap approximately 2/16 inch from flame. Don't let the straw enter the flame. Allow the plastic to soften for about 3-4 seconds.
4. Let go of the button on the lighter releasing the flame. Immediately take the soft part of the straw and press it flat against the warm metal guard of the lighter. Do not press too hard, just enough to lightly seal the plastic. The seal should be a very thin layer that closes it shut.
Step 2: Create the Aperture
5. Take out the pin and lightly puncture the plastic. Make sure the aperture is in the center of the straw. When puncturing the straw, have the needle perpendicular (right angle) to the sealed surface.
6. Put your mouth over the flute (part that connects to the can) or straw and blow some air through it. This will ensure the cap is not still sealed.
Step 3: Test It and Use It
7. Test out the cap with a well-shaken can. Wear a glove. Use in a well ventilated area. Do a test spray on a piece of cardboard to see what type of mark it makes.