The cap for the wash-free airbrush paint bottle is compatible with Dispai wash-free airbrushes. The paint bottle uses a standard 50 ml graduated dispensing bottle, while the needle features a stainless steel push‑fit dispensing needle (with a tip diameter less than 1 mm). The tubing is made of either silicone soft tubing or Teflon tubing, with an inner diameter of 4 mm and an outer diameter of 6 mm. The paper gasket originally housed inside the bottle’s cap can be removed and repurposed for use with this cap.

The cap is divided into three distinct sections, designated as Cap 1, Cap 2, and Cap 3.

Parameter details are shown in the diagram:

According to the description in the video “LEY’s Model World” by Bilibili uploader LEY, silicone tubing tends to exhibit unusual behavior when storing nitrocellulose lacquer—his recommended workaround is to use Teflon tubing.
After purchasing 4×6 mm Teflon tubing for testing, I found that it fit snugly inside the cap. Additionally, I discovered that Teflon tubing in the 4.1×6 mm size is also available; therefore, the dimensions provided should be sufficient to securely hold the tubing in place.

An extended version of Cap 3 is also included—should you lose your original Cap 3, this alternative can serve as a temporary solution.

It’s a bit tight at first; giving it a few extra turns back and forth will help it loosen up.

The “loosened” version features a thread inner diameter increased by 0.2 mm, offering a slightly more relaxed fit.