Piston Insertion with Air Bleed-Out Strips / Strings

Piston Insertion with Air Bleed-Out Strips / Strings

Piston Insertion with Air Bleed-Out Strips / Strings

For Use with:

 

Purpose

Traditional o-ring style pistons do not have air channels to evacuate (bleed) the trapped air inside cartridge barrels as the sealing pistons are inserted.

This white paper illustrates the method of allowing the trapped air to escape and properly seal the cartridge barrels.

The piston insertion filament (air bleed string) provides a controlled pathway for air to exit while seating the pistons into the cartridge barrels.

Cartridge Parts / Components

Each cartridge set typically includes:

  • 1x Dual-Barrel Cartridge (for example 4:1 ratio)
  • 2x Pistons (pre-sized for the cartridge)
  • 1x Sealing Cap and plug

Sold separately:

  • Piston Insertion Filament/String (typically 0.5–1.0 mm thick, nylon or similar material)


 

When and why to Use the Bleed Filament or Strip

Problem: Without using a strip to Bleed Trapped Air:

Inserting pistons without a venting path can trap air between the piston and material leads to 1) Inaccurate mix ratios, 2) Premature empty signals, 3) Blobs of air in dispensed material

Solution:  The bleed-out string is a simple and effective tool to vent this trapped air during piston insertion.

Step-by-Step Instructions

Step 1: Prepare Your Workspace

  • Have the cartridge, pistons, and bleed strip/filament on hand.
  • Wear gloves to maintain cleanliness and avoid contaminating material surfaces.
  • These steps should begin only after the cartridge has been filled with material.

Step 2: Insert the Bleed String

  1. Take a piece of the bleed filament (approx. 6–8 inches long).
  2. Place one end of the string inside one cartridge barrel, such that the filament rests along the inner wall.
  3. Let the other end hang outside the cartridge — you’ll remove this later.
  4. Repeat for the second barrel (if using both).

✅ Tip: The strip should run vertically inside the back of the barrel.

Step 3: Insert Pistons

  1. Align the piston directly above the cartridge barrel opening.
  2. Slowly press the piston straight into the back of the barrel, allowing the filament to stay partially pinched between the wall and piston.
  3. As the piston moves downward, the filament forms a temporary channel for air to escape.

⚠️ Important: Do not press too fast; let the air escape gradually to avoid resistance or misalignment.

Step 4: Remove the Bleed Filament

  1. Once the piston is fully seated:
    • Grasp the exposed end of the strip or filament.
    • Gently pull upward to extract it from the cartridge.
    • The piston will remain inside the barrel and is now sealed and air-free.
  2. Repeat for the other side if applicable.

✅ The pistons should now be fully seated with no trapped air.

Troubleshooting Tips

Issue

Cause

Solution

Piston is hard to insert

No bleed string or string blocked

Ensure filament is inserted properly

Air pockets during dispensing

Air trapped under piston

Reinsert with new filament

Filament won’t pull out

Inserted too deep or folded

Pull slowly; do not yank; reinsert if needed

Best Practices

  • For each piston to insert, either wipe the strip / filament clean, or use a fresh filament.
  • Avoid material contamination across the two barrels, as that can induce the curing process or have other unintended consequences.
  • Store the sealed cartridges and pistons in a clean, dry area.

Technical Contact

For support inquiries, contact:   Perigee Direct Technical Support
📧 support@perigeedirect.com
📞 (817) 381-9398
🌐 www.perigeedirect.com